feat : ContextualSerializer 를 사용하는 직렬화 예제 코드 추가

네이버 로그인 기능 샘플 코드 추가

놀이터(예제 코드 작성)/jackson/.gitignore

@@ -0,0 +1,37 @@
+HELP.md
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/

놀이터(예제 코드 작성)/jackson/build.gradle.kts

@@ -0,0 +1,44 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+	id("java")
+	id("org.springframework.boot") version "2.6.1"
+	id("io.spring.dependency-management") version "1.0.11.RELEASE"
+	kotlin("jvm") version "1.6.0"
+	kotlin("plugin.spring") version "1.6.0"
+	kotlin("plugin.jpa") version "1.6.0"
+}
+
+group = "com.banjjoknim"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_11
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter-data-jpa")
+	implementation("org.springframework.boot:spring-boot-starter-security")
+	implementation("org.springframework.boot:spring-boot-starter-validation")
+	implementation("org.springframework.boot:spring-boot-starter-web")
+	implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
+	implementation("org.jetbrains.kotlin:kotlin-reflect")
+	implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
+	runtimeOnly("com.h2database:h2")
+	runtimeOnly("mysql:mysql-connector-java")
+	runtimeOnly("org.mariadb.jdbc:mariadb-java-client")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+	testImplementation("org.springframework.security:spring-security-test")
+}
+
+tasks.withType<KotlinCompile> {
+	kotlinOptions {
+		freeCompilerArgs = listOf("-Xjsr305=strict")
+		jvmTarget = "11"
+	}
+}
+
+tasks.withType<Test> {
+	useJUnitPlatform()
+}

놀이터(예제 코드 작성)/jackson/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.3.1-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

놀이터(예제 코드 작성)/jackson/gradlew

@@ -0,0 +1,234 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+APP_NAME="Gradle"
+APP_BASE_NAME=${0##*/}
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

놀이터(예제 코드 작성)/jackson/gradlew.bat

@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

놀이터(예제 코드 작성)/jackson/settings.gradle.kts

@@ -0,0 +1 @@
+rootProject.name = "jackson"

놀이터(예제 코드 작성)/jackson/src/main/kotlin/com/banjjoknim/playground/JacksonApplication.kt

@@ -0,0 +1,11 @@
+package com.banjjoknim.playground
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.boot.runApplication
+
+@SpringBootApplication
+class PlaygroundApplication
+
+fun main(args: Array<String>) {
+	runApplication<PlaygroundApplication>(*args)
+}

놀이터(예제 코드 작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/common/Cars.kt

@@ -0,0 +1,51 @@
+package com.banjjoknim.playground.jackson.common
+
+import com.banjjoknim.playground.jackson.jsonserialize.ContextualCarSerializer
+import com.banjjoknim.playground.jackson.jsonserialize.UsingJsonSerializeAnnotationCarSerializer
+import com.fasterxml.jackson.databind.annotation.JsonSerialize
+
+data class Car(
+    val name: String,
+    val price: Int = 10000000,
+    val owner: Owner = Owner()
+)
+
+data class CarUsingNoAnnotation(
+    val name: String = "banjjoknim",
+    val secret: String = "secret",
+    val price: Int = 10000000,
+    val owner: Owner = Owner()
+)
+
+data class CarUsingJsonSerializeAnnotationCarSerializer(
+    val name: String = "banjjoknim",
+    @JsonSerialize(using = UsingJsonSerializeAnnotationCarSerializer::class)
+    val secret: String = "secret",
+    val price: Int = 10000000,
+    val owner: Owner = Owner()
+)
+
+data class CarUsingContextualSerializerWithSecretAnnotation(
+    val name: String = "banjjoknim",
+    @JsonSerialize(using = ContextualCarSerializer::class)
+    @field:Secret("hello world!!")
+    val secret: String = "secret",
+    val price: Int = 10000000,
+    val owner: Owner = Owner()
+)
+
+data class CarUsingContextualSerializerWithNoSecretAnnotation(
+    val name: String = "banjjoknim",
+    @JsonSerialize(using = ContextualCarSerializer::class)
+    val secret: String = "secret",
+    val price: Int = 10000000,
+    val owner: Owner = Owner()
+)
+
+data class CarUsingSecretAnnotation(
+    val name: String = "banjjoknim",
+    @field:Secret("****")
+    val secret: String = "secret",
+    val price: Int = 10000000,
+    val owner: Owner = Owner()
+)

놀이터(예제 코드 작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/common/Owner.kt

@@ -0,0 +1,3 @@
+package com.banjjoknim.playground.jackson.common
+
+data class Owner(val name: String = "ban", val age: Int = 30)

놀이터(예제 코드 작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/common/Secret.kt

@@ -0,0 +1,16 @@
+package com.banjjoknim.playground.jackson.common
+
+import com.fasterxml.jackson.annotation.JacksonAnnotation
+
+/**
+ * [jackson-annotations](https://www.baeldung.com/jackson-annotations) 참고.
+ *
+ * @see com.fasterxml.jackson.annotation.JacksonAnnotation
+ * @see com.fasterxml.jackson.annotation.JacksonAnnotationsInside
+ */
+@Retention(AnnotationRetention.RUNTIME)
+@Target(AnnotationTarget.FIELD) // 현재 상황에서는 PROPERTY 로 적용할 경우 제대로 적용되지 않는다. 아마 어노테이션 자체가 자바 기반으로 사용되어 PROPERTY 를 인식하지 못하는 것 같다(자바에서는 PROPERTY 타입을 사용할 수 없음).
+@JacksonAnnotation // NOTE: important; MUST be considered a 'Jackson' annotation to be seen(or recognized otherwise via AnnotationIntrospect.isHandled())
+annotation class Secret(
+    val substituteValue: String = ""
+)

놀이터(예제 코드 작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/jsonserialize/CarSerializers.kt

@@ -0,0 +1,179 @@
+package com.banjjoknim.playground.jackson.jsonserialize
+
+import com.banjjoknim.playground.jackson.common.Car
+import com.banjjoknim.playground.jackson.common.Secret
+import com.fasterxml.jackson.core.JsonGenerator
+import com.fasterxml.jackson.databind.BeanDescription
+import com.fasterxml.jackson.databind.BeanProperty
+import com.fasterxml.jackson.databind.JsonSerializer
+import com.fasterxml.jackson.databind.SerializationConfig
+import com.fasterxml.jackson.databind.SerializerProvider
+import com.fasterxml.jackson.databind.introspect.Annotated
+import com.fasterxml.jackson.databind.introspect.AnnotatedMember
+import com.fasterxml.jackson.databind.introspect.JacksonAnnotationIntrospector
+import com.fasterxml.jackson.databind.module.SimpleModule
+import com.fasterxml.jackson.databind.ser.BeanPropertyWriter
+import com.fasterxml.jackson.databind.ser.BeanSerializerModifier
+import com.fasterxml.jackson.databind.ser.ContextualSerializer
+import com.fasterxml.jackson.databind.ser.std.StdSerializer
+
+/**
+ * [jackson-object-mapper-tutorial](https://www.baeldung.com/jackson-object-mapper-tutorial) 참고.
+ *
+ * [how-to-(de)serialize-field-from-object-based-on-annotation-using-jackson](https://stackoverflow.com/questions/18659835/how-to-deserialize-field-from-object-based-on-annotation-using-jackson)
+ *
+ * Custom Serializer 를 만들기 위해서는 아래와 같이 StdSerializer<T> 를 상속해야 한다.
+ *
+ * 만약 어노테이션을 이용한 설정 또는 프로퍼티마다 다르게 작동하는 Serializer 를 만들고 싶다면 JsonSerializer 의 add-on interface 인 ContextualSerializer 를 구현하면 된다.
+ *
+ * JsonSerializer<T> 만 확장할 경우엔 애노테이션 정보를 얻을 수 없다. 추가적으로 ContextualSerializer 인터페이스를 구현해주면 createContextual() 메서드를 구현해줘야 하는데 두번째 인자로 넘어오는 BeanProperty 를 이용해 애노테이션 정보를 구할 수 있다.
+ *
+ * ContexutalSerializer 를 사용하는 방법은 [TestContextualSerialization](https://github.com/FasterXML/jackson-databind/blob/master/src/test/java/com/fasterxml/jackson/databind/contextual/TestContextualSerialization.java) 참고하도록 한다.
+ *
+ * Custom Serializer 가 JsonSerializer<T> 와 ContextualSerialier 를 모두 구현할 경우 createContextual() 함수가 먼저 호출된다.
+ *
+ * @see com.fasterxml.jackson.databind.ser.std.StdSerializer
+ * @see com.fasterxml.jackson.databind.ser.std.StringSerializer
+ * @see com.fasterxml.jackson.databind.ser.ContextualSerializer
+ */
+class CarSerializer : StdSerializer<Car>(Car::class.java) {
+    override fun serialize(value: Car, gen: JsonGenerator, provider: SerializerProvider) {
+        gen.writeStartObject()
+        gen.writeStringField("name", value.name)
+        gen.writeNumberField("price", value.price)
+        gen.writeEndObject()
+    }
+}
+
+class CarNameSerializer : StdSerializer<Car>(Car::class.java) {
+    override fun serialize(value: Car, gen: JsonGenerator, provider: SerializerProvider) {
+        gen.writeStartObject()
+        gen.writeStringField("name", value.name)
+        gen.writeEndObject()
+    }
+}
+
+class CarPriceSerializer : StdSerializer<Car>(Car::class.java) {
+    override fun serialize(value: Car, gen: JsonGenerator, provider: SerializerProvider) {
+        gen.writeStartObject()
+        gen.writeNumberField("price", value.price)
+        gen.writeEndObject()
+    }
+}
+
+class CarNameOwnerSerializer : StdSerializer<Car>(Car::class.java) {
+    override fun serialize(value: Car, gen: JsonGenerator, provider: SerializerProvider) {
+        gen.writeStartObject()
+        gen.writeStringField("name", value.name)
+        gen.writeObjectField("owner", value.owner)
+        gen.writeEndObject()
+    }
+}
+
+class CarNameOwnerNameSerializer : StdSerializer<Car>(Car::class.java) {
+    override fun serialize(value: Car, gen: JsonGenerator, provider: SerializerProvider) {
+        gen.writeStartObject()
+        gen.writeStringField("name", value.name)
+        gen.writeObjectFieldStart("owner")
+        gen.writeStringField("name", value.owner.name)
+        gen.writeEndObject()
+    }
+}
+
+class UsingJsonSerializeAnnotationCarSerializer : StdSerializer<String>(String::class.java) {
+    override fun serialize(value: String, gen: JsonGenerator, provider: SerializerProvider) {
+        gen.writeString("****")
+    }
+}
+
+class ContextualCarSerializer(
+    private val substituteValue: String = "this is default value in ContextualCarSerializer"
+) : StdSerializer<String>(String::class.java), ContextualSerializer {
+    override fun serialize(value: String, gen: JsonGenerator, provider: SerializerProvider) {
+        gen.writeString(substituteValue)
+    }
+
+    override fun createContextual(provider: SerializerProvider, property: BeanProperty): JsonSerializer<*> {
+        val annotation = property.getAnnotation(Secret::class.java)
+        if (annotation != null) {
+            return ContextualCarSerializer(annotation.substituteValue)
+        }
+        return ContextualCarSerializer()
+//        JsonMappingException: Can not write a field name, expecting a value (through reference chain: com.banjjoknim.playground.jackson.common.CarUsingContextualSerializerWithNoSecretAnnotation["secret"])
+//        return provider.findKeySerializer(property.type, property)
+    }
+}
+
+/**
+ * AnnotationIntrospector 를 상속한 JacksonAnnotationIntrospector 은 Jackson 라이브러리가 직렬화/역직렬화시 `JacksonAnnotation` 정보를 어떻게 처리할지에 대한 정보가 정의되어 있는 클래스다.
+ *
+ * 따라서 어노테이션별로 어떻게 처리할지 재정의하고 싶다면 이 녀석을 override 해준뒤 ObjectMapper 에 등록해주면 된다.
+ *
+ * 등록할 때는 `ObjectMapper#setAnnotationIntrospector()` 를 사용한다.
+ *
+ * [FasterXML - AnnotationIntrospector](https://github.com/FasterXML/jackson-docs/wiki/AnnotationIntrospector)
+ *
+ * @see com.fasterxml.jackson.databind.introspect.JacksonAnnotationIntrospector#
+ * @see com.fasterxml.jackson.databind.ObjectMapper
+ *
+ */
+class SecretAnnotationIntrospector : JacksonAnnotationIntrospector() {
+    /**
+     *
+     * `@JsonIgnore` 를 적용했을 때 무시할지 여부를 판단하는 함수이다.
+     *
+     * 따라서 직렬화 / 역직렬화시 무시하고 싶은 프로퍼티가 있다면 이 함수를 override 하면 된다.
+     */
+    override fun hasIgnoreMarker(m: AnnotatedMember): Boolean {
+        return super.hasIgnoreMarker(m)
+    }
+
+    /**
+     * `@JsonSerailize` 가 붙은 어노테이션의 처리를 재정의할 때 override 하는 함수이다.
+     *
+     * 자세한 내용은 JacksonAnnotationIntrospector#findSerializer() 의 구현을 살펴보도록 한다.
+     *
+     * 특정 프로퍼티에 대해 어떤 Serializer 를 사용할 것인지 결정하는 함수이다.
+     *
+     * 따라서 특정 조건에 따라 직렬화 처리에 사용할 Serializer 를 정의하고 싶다면 이 함수를 override 하면 된다.
+     */
+    override fun findSerializer(a: Annotated): Any? {
+        val annotation = a.getAnnotation(Secret::class.java)
+        if (annotation != null) {
+            return SecretAnnotationSerializer(annotation.substituteValue)
+        }
+        return super.findSerializer(a) // 기존 JacksonAnnotationIntrospector 의 것을 사용한다.
+    }
+}
+
+class SecretAnnotationSerializer(private val substituteValue: String) : StdSerializer<String>(String::class.java) {
+    override fun serialize(value: String, gen: JsonGenerator, provider: SerializerProvider) {
+        gen.writeString(substituteValue)
+    }
+}
+
+/**
+ * 직렬화될 프로퍼티를 수정하도록 하는 방법이다.
+ *
+ * BeanSerializerModifier#changeProperties() 를 재정의한 뒤,
+ *
+ * SimpleModule 을 이용해서 ObjectMapper 에 등록한다.
+ *
+ * 아래처럼 하면 직렬화 대상에서 완전히 제외된다(`@JsonIgnore`와 동일한 효과).
+ *
+ * @see com.fasterxml.jackson.databind.ser.BeanSerializerModifier
+ * @see com.fasterxml.jackson.databind.module.SimpleModule
+ */
+class SecretBeanSerializerModifier : BeanSerializerModifier() {
+    override fun changeProperties(
+        config: SerializationConfig,
+        beanDesc: BeanDescription,
+        beanProperties: MutableList<BeanPropertyWriter>
+    ): MutableList<BeanPropertyWriter> {
+        SimpleModule()
+        return beanProperties
+            .filter { property -> property.getAnnotation(Secret::class.java) == null }
+            .toMutableList()
+//        return super.changeProperties(config, beanDesc, beanProperties)
+    }
+}

놀이터(예제 코드 작성)/jackson/src/main/resources/application.properties

@@ -0,0 +1 @@
+

놀이터(예제 코드 작성)/jackson/src/test/kotlin/com/banjjoknim/playground/JacksonApplicationTests.kt

@@ -0,0 +1,13 @@
+package com.banjjoknim.playground
+
+import org.junit.jupiter.api.Test
+import org.springframework.boot.test.context.SpringBootTest
+
+@SpringBootTest
+class JacksonApplicationTests {
+
+	@Test
+	fun contextLoads() {
+	}
+
+}

놀이터(예제 코드 작성)/jackson/src/test/kotlin/com/banjjoknim/playground/jackson/jsonserialize/CarSerializersTest.kt

@@ -0,0 +1,279 @@
+package com.banjjoknim.playground.jackson.jsonserialize
+
+import com.banjjoknim.playground.jackson.common.Car
+import com.banjjoknim.playground.jackson.common.CarUsingContextualSerializerWithNoSecretAnnotation
+import com.banjjoknim.playground.jackson.common.CarUsingContextualSerializerWithSecretAnnotation
+import com.banjjoknim.playground.jackson.common.CarUsingJsonSerializeAnnotationCarSerializer
+import com.banjjoknim.playground.jackson.common.CarUsingNoAnnotation
+import com.banjjoknim.playground.jackson.common.CarUsingSecretAnnotation
+import com.banjjoknim.playground.jackson.common.Owner
+import com.fasterxml.jackson.databind.AnnotationIntrospector
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.databind.module.SimpleModule
+import com.fasterxml.jackson.module.kotlin.registerKotlinModule
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+
+/**
+ * @see com.fasterxml.jackson.databind.ObjectMapper
+ * @see com.fasterxml.jackson.databind.module.SimpleModule
+ * @see com.fasterxml.jackson.databind.ser.DefaultSerializerProvider
+ * @see com.fasterxml.jackson.databind.ser.BeanSerializer -> 객체를 직렬화할때 사용되는 Serializer
+ * @see com.fasterxml.jackson.core.json.WriterBasedJsonGenerator
+ * @see com.fasterxml.jackson.databind.ser.std.BeanSerializerBase
+ * @see com.fasterxml.jackson.databind.ser.BeanPropertyWriter
+ */
+class CarSerializersTest {
+
+    private lateinit var mapper: ObjectMapper
+
+    companion object {
+        private val owner = Owner("ban", 30)
+        private val car = Car("banjjoknim", 10_000_000, owner)
+        private val carUsingNoAnnotation = CarUsingNoAnnotation()
+        private val carUsingJsonSerializeAnnotationCarSerializer = CarUsingJsonSerializeAnnotationCarSerializer()
+        private val carUsingContextualSerializerWithSecretAnnotation =
+            CarUsingContextualSerializerWithSecretAnnotation()
+        private val carUsingContextualSerializerWithNoSecretAnnotation =
+            CarUsingContextualSerializerWithNoSecretAnnotation()
+        private val carUsingSecretAnnotation = CarUsingSecretAnnotation()
+    }
+
+    @BeforeEach
+    fun setup() {
+        mapper = ObjectMapper().registerKotlinModule()
+    }
+
+    @Test
+    fun `기본 ObjectMapper의 동작을 테스트한다`() {
+        // given
+
+        // when
+        val result = mapper.writeValueAsString(car)
+
+        // then
+        assertThat(result).isEqualTo("""{"name":"banjjoknim","price":10000000,"owner":{"name":"ban","age":30}}""")
+    }
+
+    @DisplayName("등록된 커스텀 직렬화기의 동작을 테스트한다")
+    @Nested
+    inner class CarSerializerTestCases {
+        @Test
+        fun `자동차의 모든 필드만 직렬화한다`() {
+            // given
+            val module = SimpleModule()
+            module.addSerializer(Car::class.java, CarSerializer())
+            mapper.registerModule(module)
+
+            // when
+            val result = mapper.writeValueAsString(car)
+
+            // then
+            assertThat(result).isEqualTo("""{"name":"banjjoknim","price":10000000}""")
+        }
+
+        @Test
+        fun `자동차의 이름만 직렬화한다`() {
+            // given
+            val module = SimpleModule()
+            module.addSerializer(Car::class.java, CarNameSerializer())
+            mapper.registerModule(module)
+
+            // when
+            val result = mapper.writeValueAsString(car)
+
+            // then
+            assertThat(result).isEqualTo("""{"name":"banjjoknim"}""")
+        }
+
+        @Test
+        fun `자동차의 가격만 직렬화한다`() {
+            // given
+            val module = SimpleModule()
+            module.addSerializer(Car::class.java, CarPriceSerializer())
+            mapper.registerModule(module)
+
+            // when
+            val result = mapper.writeValueAsString(car)
+
+            // then
+            assertThat(result).isEqualTo("""{"price":10000000}""")
+        }
+
+        @Test
+        fun `자동차의 이름과 오너의 모든 필드를 직렬화한다`() {
+            // given
+            val module = SimpleModule()
+            module.addSerializer(Car::class.java, CarNameOwnerSerializer())
+            mapper.registerModule(module)
+
+            // when
+            val result = mapper.writeValueAsString(car)
+
+            // then
+            assertThat(result).isEqualTo("""{"name":"banjjoknim","owner":{"name":"ban","age":30}}""")
+        }
+
+        @Test
+        fun `자동차의 이름과 오너의 이름만 직렬화한다`() {
+            // given
+            val module = SimpleModule()
+            module.addSerializer(Car::class.java, CarNameOwnerNameSerializer())
+            mapper.registerModule(module)
+
+            // when
+            val result = mapper.writeValueAsString(car)
+
+            // then
+            assertThat(result).isEqualTo("""{"name":"banjjoknim","owner":{"name":"ban"}}""")
+        }
+
+        @Test
+        fun `아무 어노테이션도 적용하지 않고 직렬화한다`() {
+            // given
+
+            // when
+            val actual = mapper.writeValueAsString(carUsingNoAnnotation)
+
+            // then
+            assertThat(actual).isEqualTo("""{"name":"banjjoknim","secret":"secret","price":10000000,"owner":{"name":"ban","age":30}}""")
+        }
+
+        @Test
+        fun `@JsonSerialize 어노테이션을 적용하여 직렬화한다`() {
+            // given
+
+            // when
+            val actual = mapper.writeValueAsString(carUsingJsonSerializeAnnotationCarSerializer)
+
+            // then
+            assertThat(actual).isEqualTo("""{"name":"banjjoknim","secret":"****","price":10000000,"owner":{"name":"ban","age":30}}""")
+        }
+
+        @Test
+        fun `ContextualSerializer 를 상속 받은 구현체를 이용해서 직렬화한다`() {
+            // given
+
+            // when
+            val actualWithSecretAnnotation = mapper.writeValueAsString(carUsingContextualSerializerWithSecretAnnotation)
+            val actualWithNoSecretAnnotation =
+                mapper.writeValueAsString(carUsingContextualSerializerWithNoSecretAnnotation)
+
+            // then
+            assertThat(actualWithSecretAnnotation).isEqualTo("""{"name":"banjjoknim","secret":"hello world!!","price":10000000,"owner":{"name":"ban","age":30}}""")
+            assertThat(actualWithNoSecretAnnotation).isEqualTo("""{"name":"banjjoknim","secret":"this is default value in ContextualCarSerializer","price":10000000,"owner":{"name":"ban","age":30}}""")
+        }
+
+        @Test
+        fun `@Secret 어노테이션, AnnotationIntrospector 을 적용하여 직렬화한다`() {
+            // given
+            mapper.setAnnotationIntrospector(SecretAnnotationIntrospector())
+
+            // when
+            val actual = mapper.writeValueAsString(carUsingSecretAnnotation)
+
+            // then
+            assertThat(actual).isEqualTo("""{"name":"banjjoknim","secret":"****","price":10000000,"owner":{"name":"ban","age":30}}""")
+        }
+
+        @Test
+        fun `@Secret 어노테이션, BeanSerializerModifier 를 적용하여 직렬화한다`() {
+            // given
+            val module = object : SimpleModule() {
+                override fun setupModule(context: SetupContext) {
+                    super.setupModule(context)
+                    context.addBeanSerializerModifier(SecretBeanSerializerModifier())
+                }
+            }
+            mapper.registerModule(module)
+
+            // when
+            val actual = mapper.writeValueAsString(carUsingSecretAnnotation)
+
+            // then
+            assertThat(actual).isEqualTo("""{"name":"banjjoknim","price":10000000,"owner":{"name":"ban","age":30}}""")
+        }
+
+        /**
+         *
+         * Kotlin + Spring Boot 를 사용한다면 `com.fasterxml.jackson.module:jackson-module-kotlin` 의존성을 사용할 것이다.
+         *
+         * 이를 사용하면 기본 생성자 없이도 `@RequestBody` 에서 json 을 객체로 역직렬화 할 수 있다.
+         *
+         * `com.fasterxml.jackson.module:jackson-module-kotlin` 에서 이러한 역할을 해주는 것이 KotlinAnnotationIntrospector 이다.
+         *
+         * 하지만 새로운 AnnotationIntrospector 를 등록하면 KotlinAnnotationIntrospector 가 무시되어 기본생성자 없이는 `@RequestBody` 객체를 만들지 못하게 된다.
+         *
+         * 따라서 아래와 같이 기존의 AnnotationIntrospector 도 등록해주어야 한다.
+         *
+         * 이는 AnnotationIntrospector.Pair 도우미 클래스를 사용해서 할 수 있다.
+         *
+         * 이때, 순서대로 기본 Introspector, 보조 Introspector 로 등록된다.
+         *
+         * [AnnotationIntrospector](https://github.com/FasterXML/jackson-docs/wiki/AnnotationIntrospector)
+         *
+         * @see com.fasterxml.jackson.databind.ObjectMapper
+         * @see com.fasterxml.jackson.databind.introspect.AnnotationIntrospectorPair
+         * @see com.fasterxml.jackson.databind.AnnotationIntrospector
+         * @see com.fasterxml.jackson.module.kotlin.KotlinAnnotationIntrospector
+         */
+        @Test
+        fun `Kotlin + Spring Boot를 사용하면 기본적으로 3가지의 AnnotationIntrospector 가 ObjectMapper 에 존재한다`() {
+            // given
+            val originalAnnotationIntrospector = mapper.serializationConfig.annotationIntrospector
+
+            // when
+            val allIntrospectorNames = mapper.serializationConfig.annotationIntrospector.allIntrospectors()
+                .map { annotationIntrospector -> annotationIntrospector::class.simpleName }
+
+            // then
+            assertThat(originalAnnotationIntrospector.allIntrospectors()).hasSize(3)
+            assertThat(allIntrospectorNames[0]).isEqualTo("KotlinAnnotationIntrospector")
+            assertThat(allIntrospectorNames[1]).isEqualTo("JacksonAnnotationIntrospector")
+            assertThat(allIntrospectorNames[2]).isEqualTo("KotlinNamesAnnotationIntrospector")
+        }
+
+        @Test
+        fun `Kotlin + Spring Boot 를 사용할 시 ObjectMapper 에 새로운 AnnotationIntrospector 를 추가하면 KotlinAnnotationIntrospector 가 무시된다`() {
+            // given
+            val originalAnnotationIntrospector = mapper.serializationConfig.annotationIntrospector
+
+            // when
+            mapper.setAnnotationIntrospector(SecretAnnotationIntrospector())
+            val allIntrospectorNames = mapper.serializationConfig.annotationIntrospector.allIntrospectors()
+                .map { annotationIntrospector -> annotationIntrospector::class.simpleName }
+
+            // then
+            assertThat(originalAnnotationIntrospector.allIntrospectors()).hasSize(3)
+            assertThat(allIntrospectorNames).hasSize(1)
+            assertThat(allIntrospectorNames[0]).isEqualTo("SecretAnnotationIntrospector")
+        }
+
+        @Test
+        fun `Kotlin + Spring Boot 를 사용할 시 ObjectMapper 에 새로운 AnnotationIntrospector 를 추가할 때 Pair 로 추가하면 KotlinAnnotationIntrospector 가 무시되지 않는다`() {
+            // given
+            val originalAnnotationIntrospector = mapper.serializationConfig.annotationIntrospector
+
+            // when
+            mapper.setAnnotationIntrospector(
+                AnnotationIntrospector.pair(
+                    SecretAnnotationIntrospector(),
+                    originalAnnotationIntrospector
+                ) // 내부 구현은 아래와 같다.
+//                AnnotationIntrospectorPair(SecretAnnotationIntrospector(), originalAnnotationIntrospector)
+            )
+            val allIntrospectorNames = mapper.serializationConfig.annotationIntrospector.allIntrospectors()
+                .map { annotationIntrospector -> annotationIntrospector::class.simpleName }
+
+            // then
+            assertThat(allIntrospectorNames).hasSize(4)
+            assertThat(allIntrospectorNames[0]).isEqualTo("SecretAnnotationIntrospector")
+            assertThat(allIntrospectorNames[1]).isEqualTo("KotlinAnnotationIntrospector")
+            assertThat(allIntrospectorNames[2]).isEqualTo("JacksonAnnotationIntrospector")
+            assertThat(allIntrospectorNames[3]).isEqualTo("KotlinNamesAnnotationIntrospector")
+        }
+    }
+}

놀이터(예제 코드 작성)/playground/build.gradle.kts

@@ -19,6 +19,7 @@ repositories {
 
 dependencies {
 	implementation("org.springframework.boot:spring-boot-starter-data-jpa")
+	implementation("org.springframework.boot:spring-boot-starter-security")
 	implementation("org.springframework.boot:spring-boot-starter-validation")
 	implementation("org.springframework.boot:spring-boot-starter-web")
 	implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
@@ -28,6 +29,7 @@ dependencies {
 	runtimeOnly("mysql:mysql-connector-java")
 	runtimeOnly("org.mariadb.jdbc:mariadb-java-client")
 	testImplementation("org.springframework.boot:spring-boot-starter-test")
+	testImplementation("org.springframework.security:spring-security-test")
 }
 
 tasks.withType<KotlinCompile> {
@@ -40,7 +42,3 @@ tasks.withType<KotlinCompile> {
 tasks.withType<Test> {
 	useJUnitPlatform()
 }
-
-tasks.named("jar") {
-	enabled = false
-}

놀이터(예제 코드 작성)/playground/src/main/resources/application.properties

@@ -0,0 +1 @@
+

놀이터(예제 코드 작성)/spring-event/.gitignore

@@ -0,0 +1,37 @@
+HELP.md
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/

놀이터(예제 코드 작성)/spring-event/build.gradle.kts

@@ -0,0 +1,46 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+	id("java")
+	id("org.springframework.boot") version "2.6.1"
+	id("io.spring.dependency-management") version "1.0.11.RELEASE"
+	kotlin("jvm") version "1.6.0"
+	kotlin("plugin.spring") version "1.6.0"
+	kotlin("plugin.jpa") version "1.6.0"
+}
+
+group = "com.banjjoknim"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_11
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter-data-jpa")
+	implementation("org.springframework.boot:spring-boot-starter-validation")
+	implementation("org.springframework.boot:spring-boot-starter-web")
+	implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
+	implementation("org.jetbrains.kotlin:kotlin-reflect")
+	implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
+	runtimeOnly("com.h2database:h2")
+	runtimeOnly("mysql:mysql-connector-java")
+	runtimeOnly("org.mariadb.jdbc:mariadb-java-client")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}
+
+tasks.withType<KotlinCompile> {
+	kotlinOptions {
+		freeCompilerArgs = listOf("-Xjsr305=strict")
+		jvmTarget = "11"
+	}
+}
+
+tasks.withType<Test> {
+	useJUnitPlatform()
+}
+
+tasks.named("jar") {
+	enabled = false
+}

놀이터(예제 코드 작성)/spring-event/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.3.1-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

놀이터(예제 코드 작성)/spring-event/gradlew

@@ -0,0 +1,234 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+APP_NAME="Gradle"
+APP_BASE_NAME=${0##*/}
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

놀이터(예제 코드 작성)/spring-event/gradlew.bat

@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

놀이터(예제 코드 작성)/spring-event/settings.gradle.kts

@@ -0,0 +1 @@
+rootProject.name = "springEvent"

놀이터(예제 코드 작성)/spring-event/src/main/kotlin/com/banjjoknim/playground/SpringEventApplication.kt

@@ -0,0 +1,11 @@
+package com.banjjoknim.playground
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.boot.runApplication
+
+@SpringBootApplication
+class SpringEventApplication
+
+fun main(args: Array<String>) {
+	runApplication<SpringEventApplication>(*args)
+}

놀이터(예제 코드 작성)/spring-event/src/test/kotlin/com/banjjoknim/playground/SpringEventApplicationTests.kt

@@ -0,0 +1,13 @@
+package com.banjjoknim.playground
+
+import org.junit.jupiter.api.Test
+import org.springframework.boot.test.context.SpringBootTest
+
+@SpringBootTest
+class SpringEventApplicationTests {
+
+	@Test
+	fun contextLoads() {
+	}
+
+}

놀이터(예제 코드 작성)/spring-security/.gitignore

@@ -0,0 +1,37 @@
+HELP.md
+.gradle
+build/
+!gradle/wrapper/gradle-wrapper.jar
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+bin/
+!**/src/main/**/bin/
+!**/src/test/**/bin/
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+out/
+!**/src/main/**/out/
+!**/src/test/**/out/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+
+### VS Code ###
+.vscode/

놀이터(예제 코드 작성)/spring-security/build.gradle.kts

@@ -0,0 +1,48 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+	id("java")
+	id("org.springframework.boot") version "2.6.1"
+	id("io.spring.dependency-management") version "1.0.11.RELEASE"
+	kotlin("jvm") version "1.6.0"
+	kotlin("plugin.spring") version "1.6.0"
+	kotlin("plugin.jpa") version "1.6.0"
+}
+
+group = "com.banjjoknim"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_11
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter-data-jpa")
+	implementation("org.springframework.boot:spring-boot-starter-security")
+
+	// OAuth2 로그인을 위해 추가. spring-boot-starter-security 의존성이 있어도 기본적으로 추가되지 않기 때문.
+	implementation("org.springframework.boot:spring-boot-starter-oauth2-client")
+
+	implementation("org.springframework.boot:spring-boot-starter-validation")
+	implementation("org.springframework.boot:spring-boot-starter-web")
+	implementation("com.fasterxml.jackson.module:jackson-module-kotlin")
+	implementation("org.jetbrains.kotlin:kotlin-reflect")
+	implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
+	runtimeOnly("com.h2database:h2")
+	runtimeOnly("mysql:mysql-connector-java")
+	runtimeOnly("org.mariadb.jdbc:mariadb-java-client")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+	testImplementation("org.springframework.security:spring-security-test")
+}
+
+tasks.withType<KotlinCompile> {
+	kotlinOptions {
+		freeCompilerArgs = listOf("-Xjsr305=strict")
+		jvmTarget = "11"
+	}
+}
+
+tasks.withType<Test> {
+	useJUnitPlatform()
+}

놀이터(예제 코드 작성)/spring-security/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.3.1-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

놀이터(예제 코드 작성)/spring-security/gradlew

@@ -0,0 +1,234 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/master/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+    APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+    [ -h "$app_path" ]
+do
+    ls=$( ls -ld "$app_path" )
+    link=${ls#*' -> '}
+    case $link in             #(
+      /*)   app_path=$link ;; #(
+      *)    app_path=$APP_HOME$link ;;
+    esac
+done
+
+APP_HOME=$( cd "${APP_HOME:-./}" && pwd -P ) || exit
+
+APP_NAME="Gradle"
+APP_BASE_NAME=${0##*/}
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+    echo "$*"
+} >&2
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+  CYGWIN* )         cygwin=true  ;; #(
+  Darwin* )         darwin=true  ;; #(
+  MSYS* | MINGW* )  msys=true    ;; #(
+  NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD=$JAVA_HOME/jre/sh/java
+    else
+        JAVACMD=$JAVA_HOME/bin/java
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD=java
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+    case $MAX_FD in #(
+      max*)
+        MAX_FD=$( ulimit -H -n ) ||
+            warn "Could not query maximum file descriptor limit"
+    esac
+    case $MAX_FD in  #(
+      '' | soft) :;; #(
+      *)
+        ulimit -n "$MAX_FD" ||
+            warn "Could not set maximum file descriptor limit to $MAX_FD"
+    esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+    APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+    CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+    JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    for arg do
+        if
+            case $arg in                                #(
+              -*)   false ;;                            # don't mess with options #(
+              /?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+                    [ -e "$t" ] ;;                      #(
+              *)    false ;;
+            esac
+        then
+            arg=$( cygpath --path --ignore --mixed "$arg" )
+        fi
+        # Roll the args list around exactly as many times as the number of
+        # args, so each arg winds up back in the position where it started, but
+        # possibly modified.
+        #
+        # NB: a `for` loop captures its iteration list before it begins, so
+        # changing the positional parameters here affects neither the number of
+        # iterations, nor the values presented in `arg`.
+        shift                   # remove old arg
+        set -- "$@" "$arg"      # push replacement arg
+    done
+fi
+
+# Collect all arguments for the java command;
+#   * $DEFAULT_JVM_OPTS, $JAVA_OPTS, and $GRADLE_OPTS can contain fragments of
+#     shell script including quotes and variable substitutions, so put them in
+#     double quotes to make sure that they get re-expanded; and
+#   * put everything else in single quotes, so that it's not re-expanded.
+
+set -- \
+        "-Dorg.gradle.appname=$APP_BASE_NAME" \
+        -classpath "$CLASSPATH" \
+        org.gradle.wrapper.GradleWrapperMain \
+        "$@"
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+        printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+        xargs -n1 |
+        sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+        tr '\n' ' '
+    )" '"$@"'
+
+exec "$JAVACMD" "$@"

놀이터(예제 코드 작성)/spring-security/gradlew.bat

@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

놀이터(예제 코드 작성)/spring-security/settings.gradle.kts

@@ -0,0 +1 @@
+rootProject.name = "spring-security"

놀이터(예제 코드 작성)/spring-security/src/main/kotlin/com/banjjoknim/playground/SpringSecurityApplication.kt

@@ -0,0 +1,11 @@
+package com.banjjoknim.playground
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.boot.runApplication
+
+@SpringBootApplication
+class SpringSecurityApplication
+
+fun main(args: Array<String>) {
+	runApplication<SpringSecurityApplication>(*args)
+}

놀이터(예제 코드 작성)/spring-security/src/main/kotlin/com/banjjoknim/playground/config/SecurityConfig.java

@@ -0,0 +1,21 @@
+package com.banjjoknim.playground.config;
+
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
+
+// @EnableWebSecurity
+public class SecurityConfig extends WebSecurityConfigurerAdapter {
+
+    @Override
+    protected void configure(HttpSecurity http) throws Exception {
+        http.csrf().disable();
+        http.authorizeHttpRequests()
+            .antMatchers("/user/**").authenticated()
+            .antMatchers("/manager/**").hasAnyRole("MANAGER", "ADMIN")
+            .antMatchers("/admin/**").hasRole("ADMIN")
+            .anyRequest().permitAll()
+            .and()
+            .formLogin()
+            .loginPage("/login");
+    }
+}

놀이터(예제 코드 작성)/spring-security/src/main/kotlin/com/banjjoknim/playground/config/security/SecurityConfiguration.kt

@@ -0,0 +1,268 @@
+package com.banjjoknim.playground.config.security
+
+import com.banjjoknim.playground.domain.auth.OAuth2Type
+import com.banjjoknim.playground.domain.user.User
+import com.banjjoknim.playground.domain.user.UserRepository
+import org.springframework.context.annotation.Bean
+import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity
+import org.springframework.security.config.annotation.web.builders.HttpSecurity
+import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity
+import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter
+import org.springframework.security.core.GrantedAuthority
+import org.springframework.security.core.userdetails.UserDetails
+import org.springframework.security.core.userdetails.UserDetailsService
+import org.springframework.security.core.userdetails.UsernameNotFoundException
+import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder
+import org.springframework.security.crypto.password.PasswordEncoder
+import org.springframework.security.oauth2.client.userinfo.DefaultOAuth2UserService
+import org.springframework.security.oauth2.client.userinfo.OAuth2UserRequest
+import org.springframework.security.oauth2.client.userinfo.OAuth2UserService
+import org.springframework.security.oauth2.core.user.OAuth2User
+import org.springframework.stereotype.Service
+
+/**
+ * OAuth2의 경우, 로그인이 완료된 뒤의 후처리가 필요하다.
+ *
+ * 1. 코드받기(인증), 2. 액세스토큰(권한) 얻기, 3. 액세스 토큰으로 사용자 정보 얻기
+ *
+ * 구글과 페이스북 로그인의 경우 코드가 필요 없다.
+ *
+ * 구글과 페이스북 측에서 우리에게 보내는 Request에 액세스 토큰과 사용자 정보등의 OAUth2 정보가 모두 포함되어 있다.
+ *
+ * 하지만 네이버, 카카오는 스프링 부트에서 기본적인 정보를 제공하지 않기 때문에 따로 해당 정보를 제공하는 클래스를 작성해야 한다.
+ *
+ * 우리는 OAuth2-Client 라는 라이브러리를 사용하고 있다.
+ *
+ * OAuth2-Client 라이브러리는 구글, 페이스북, 깃허브 등의 Provider를 기본적으로 제공해주지만, 네이버 카카오는 제공해주지 않는다.
+ *
+ * 이는 각 나라별로 OAuth2 를 지원해주는 서드 파티가 제공하는 attribute 가 모두 다르기 때문이다. 그래서 현실적으로 모든 곳을 지원해줄 수가 없다.
+ *
+ * OAuth2-Client 는 OAuth2ClientProperties 라는 클래스를 통한 자동 설정을 지원해주고 있다.
+ *
+ * OAuth2는 여러가지 방식이 있다. Authorization Code Grant Type 방식 등등..
+ *
+ * @see org.springframework.boot.autoconfigure.security.oauth2.client.OAuth2ClientProperties
+ * @see org.springframework.boot.autoconfigure.security.oauth2.client.OAuth2ClientPropertiesRegistrationAdapter
+ * @see org.springframework.security.config.oauth2.client.CommonOAuth2Provider
+ */
+@EnableWebSecurity // 스프링 시큐리티 필터가 스프링 필터체인에 등록되도록 해준다.
+@EnableGlobalMethodSecurity(prePostEnabled = true, securedEnabled = true) // 스프링 시큐리티 관련 특정 어노테이션에 대한 활성화 설정을 할 수 있다.
+class SecurityConfiguration(val userRepository: UserRepository) : WebSecurityConfigurerAdapter() {
+
+    @Bean // passwordEncoder() 메서드에서 리턴해주는 PasswordEncoder 를 스프링 빈으로 등록한다.
+    fun passwordEncoder(): PasswordEncoder { // Security 로 로그인을 하려면 비밀번호는 암호화되어 있어야 하므로 PasswordEncoder 가 필요하다.
+        return BCryptPasswordEncoder()
+    }
+
+    /**
+     * application.yml 의 spring.security.oauth2.client.registration 에 대한 설정이 없을 경우,
+     *
+     * 이 메서드를 통해 스프링 빈으로 등록된 OAuth2UserService 를 아래의 configure 메서드에 OAuth2UserService 로써 Security filter chain 에 등록하려고 하면 아래의 예외가 발생한다.
+     *
+     * 'Method springSecurityFilterChain in org.springframework.security.config.annotation.web.configuration.WebSecurityConfiguration required a bean of type 'org.springframework.security.oauth2.client.registration.ClientRegistrationRepository' that could not be found.'
+     *
+     * 따라서 application.yml 의 spring.security.oauth2.client.registration 에 대한 설정을 반드시 등록해주어야 한다.
+     *
+     * 아래는 그 예시다.
+     *
+     * application.yml
+     *
+     * ```
+     * spring:
+     *   security:
+     *     oauth2:
+     *       client:
+     *         registration:
+     *           google:
+     *             client-id: my-client-id
+     *             client-secret: my-client-secret
+     * ```
+     *
+     * 단, 네이버 카카오는 스프링 시큐리티에서 지원해주지 않으므로 따로 설정을 작성해주어야 한다.
+     */
+    @Bean
+    fun oauth2UserService(): OAuth2UserService<OAuth2UserRequest, OAuth2User> {
+        return PrincipalOAuth2UserService(passwordEncoder(), userRepository)
+    }
+
+    override fun configure(http: HttpSecurity) {
+        http.csrf().disable()
+        http.authorizeRequests() // 인증만 되면 들어갈 수 있는 주소 설정
+            .antMatchers("/user/**").hasRole("USER")
+            .antMatchers("/manager/**").hasAnyRole("MANAGER", "ADMIN")
+            .antMatchers("/admin/**").hasRole("ADMIN")
+            .anyRequest().permitAll() // 위에서 명시한 주소 외에는 모든 접근을 허용한다.
+            .and()
+            .formLogin()
+            .loginPage("/loginPage")
+            .usernameParameter("username") // 기본적으로 인증을 위해 사용자를 찾을 때 username 을 사용하는데, 이에 사용되는 파라미터 이름을 바꿔주고 싶을때 사용한다.
+            .loginProcessingUrl("/login") // /login url이 호출되면 Security 가 요청을 낚아채서 대신 로그인을 진행해준다.
+            .defaultSuccessUrl("/") // loginPage 의 url을 통해서 로그인을 하면 / 로 보내줄건데, 특정 페이지로 요청해서 로그인하게 되면 그 페이지를 그대로 보여주겠다는 의미.
+            .and()
+            .oauth2Login()
+            .loginPage("/loginPage")
+            .loginProcessingUrl("/login")
+            .userInfoEndpoint()
+            .userService(oauth2UserService())
+    }
+}
+
+/**
+ * 시큐리티가 /login 주소 요청이 오면 낚아채서 로그인을 진행해준다.
+ *
+ * 로그인 진행이 완료되면 시큐리티 session을 만들어준다 (Security ContextHolder)
+ *
+ * Security ContextHolder에 들어갈 수 있는 객체 타입은 Authentication 이다.
+ *
+ * Authentication 객체 안에는 User 정보가 있어야 한다. 이때 User 객체 타입은 UserDetails 이다.
+ *
+ * Security Session -> Authentication -> UserDetails
+ *
+ * Security ContextHolder 내부에 Authentication이 있고, 그 속에 UserDetails가 있는 형태.
+ *
+ * ```kotlin
+ * ex) 1. SecurityContextHolder.getContext().authentication.details
+ *     2. SecurityContextHolder.getContext().authentication.principal
+ *     3. SecurityContextHolder.getContext().authentication.authorities
+ *     4. ...
+ * ```
+ */
+class PrincipalDetails(
+    val user: User // 컴포지션. 일반 로그인시 사용하는 생성자
+) : UserDetails, OAuth2User {
+
+    private var _attributes: MutableMap<String, Any> = mutableMapOf()
+
+    // OAuth2 로그인시 사용하는 생성자
+    constructor(user: User, attributes: Map<String, Any>) : this(user) {
+        this._attributes = attributes.toMutableMap()
+    }
+
+    override fun getName(): String {
+        return "someName" // 크게 중요하지 않다...
+    }
+
+    override fun getAttributes(): Map<String, Any> {
+        return _attributes.toMap()
+    }
+
+    // 해당 User 의 권한을 반환하는 함수
+    override fun getAuthorities(): Collection<out GrantedAuthority> {
+        return listOf(GrantedAuthority { user.role })
+    }
+
+    override fun getPassword(): String {
+        return user.password
+    }
+
+    override fun getUsername(): String {
+        return user.username
+    }
+
+    override fun isAccountNonExpired(): Boolean {
+        return true
+    }
+
+    override fun isAccountNonLocked(): Boolean {
+        return true
+    }
+
+    override fun isCredentialsNonExpired(): Boolean {
+        return true
+    }
+
+    override fun isEnabled(): Boolean {
+        return true
+    }
+}
+
+
+/**
+ * ```
+ * 스프링 시큐리티 설정에서 loginProcessingUrl("/login") 설정을 해주었기 때문에
+ *
+ * /login url로 요청이 오면 자동으로 시큐리티가 로그인 과정을 낚아챈다.
+ *
+ * 이때 UserDetailsService 타입으로 등록되어 있는 빈을 찾아서 해당 빈에 정의된 loadUserByUsername() 을 실행한다.
+ * ```
+ *
+ * @see org.springframework.security.authentication.dao.DaoAuthenticationProvider
+ * @see org.springframework.security.authentication.dao.AbstractUserDetailsAuthenticationProvider
+ */
+@Service
+class PrincipalDetailService(private val userRepository: UserRepository) : UserDetailsService {
+    /**
+     * ```
+     * 스프링 시큐리티 세션 내부에 Authentication 객체를 넣어준다. 그리고 Authentication 객체 속에는 UserDetails 객체가 들어있다.
+     *
+     * 추가로, 이 함수가 종료될 때 @AuthenticationPrincipal 어노테이션이 만들어진다.
+     * ```
+     */
+    override fun loadUserByUsername(username: String): UserDetails {
+        val user = (userRepository.findByUsername(username)
+            ?: throw UsernameNotFoundException("can not found user by username. username: $username"))
+        return PrincipalDetails(user) // PrincipalDetails 객체가 스프링 시큐리티 세션 정보에 들어가게 된다.
+    }
+}
+
+/**
+ * ```
+ * 구글, 페이스북 등등 OAuth2 를 이용해서 받은 userRequest 데이터에 대한 후처리를 해주는 함수를 정의하는 서비스
+ *
+ * 구글 로그인 버튼 클릭 -> 구글 로그인창 -> 로그인 완료 -> 구글에서 code 리턴 ->OAuth-Client 라이브러리가 받아서 AccessToken 요청
+ *
+ * OAuth2UserRequest 정보를 이용해서 loadUser 함수 호출 -> 구글로부터 회원프로필을 받아준다.
+ * ```
+ *
+ * @see org.springframework.security.oauth2.client.userinfo.OAuth2UserService
+ * @see org.springframework.security.oauth2.client.userinfo.DefaultOAuth2UserService
+ * @see org.springframework.security.oauth2.client.userinfo.OAuth2UserRequest
+ */
+@Service
+class PrincipalOAuth2UserService(
+    val passwordEncoder: PasswordEncoder,
+    val userRepository: UserRepository
+) :
+    DefaultOAuth2UserService() { // OAuth2 로그인의 후처리를 담당한다.
+
+    /**
+     * ```
+     * 구글, 페이스북 등으로부터 받은 userRequest 데이터에 대한 후처리를 진행해주는 함수
+     *
+     * 추가로, 이 함수가 종료될 때 @AuthenticationPrincipal 어노테이션이 만들어진다.
+     * ```
+     */
+    override fun loadUser(userRequest: OAuth2UserRequest): OAuth2User {
+        println("${userRequest.clientRegistration}")
+        println("${userRequest.accessToken}")
+//        println("${userRequest.attributes}") // 5.1 버전 이전일 경우.
+        println("${userRequest.additionalParameters}") // 5.1 버전 이후일 경우.
+
+        // 강제로 회원가입 진행
+        val oAuth2Type = OAuth2Type.findByProvider(userRequest.clientRegistration.registrationId)
+        val oAuth2User = super.loadUser(userRequest)
+        val oAuth2UserInfo = oAuth2Type.createOAuth2UserInfo(oAuth2User.attributes)
+
+        val provider = oAuth2UserInfo.getProvider() // 값의 유무로 일반 로그인, OAuth2 로그인을 구분한다.
+        val providerId = oAuth2UserInfo.getProviderId()
+        val username = "${provider}_${providerId}" // OAuth2 로 로그인시, 필요 없지만 그냥 만들어준다.
+        val password = passwordEncoder.encode("비밀번호") // OAuth2 로 로그인시, 필요 없지만 그냥 만들어준다.
+        val email = oAuth2UserInfo.getEmail()
+        val role = "ROLE_USER"
+
+        // 회원가입 여부 확인 및 저장
+        var user = userRepository.findByUsername(username)
+        require(user != null) { "이미 자동으로 회원가입이 되어 있습니다." }
+        user = User(
+            username = username,
+            password = password,
+            email = email,
+            role = role,
+            provider = provider,
+            providerId = providerId
+        )
+        userRepository.save(user) // 회원정보 저장
+
+        return PrincipalDetails(user, oAuth2User.attributes) // PrincipalDetails 객체가 스프링 시큐리티 세션 정보에 들어가게 된다.
+    }
+}

놀이터(예제 코드 작성)/spring-security/src/main/kotlin/com/banjjoknim/playground/domain/auth/OAuth2Type.kt

@@ -0,0 +1,23 @@
+package com.banjjoknim.playground.domain.auth
+
+enum class OAuth2Type(
+    private val provider: String,
+    private val createUserInfo: (attributes: Map<String, Any?>) -> OAuth2UserInfo
+) {
+    GOOGLE("google", { attributes -> GoogleUserInfo(attributes) }),
+    FACEBOOK("facebook", { attributes -> FacebookUserInfo(attributes) }),
+    NAVER("naver", { attributes -> NaverUserInfo(attributes) });
+
+    fun createOAuth2UserInfo(attributes: Map<String, Any?>): OAuth2UserInfo {
+        return createUserInfo(attributes)
+    }
+
+    companion object {
+        fun findByProvider(provider: String): OAuth2Type {
+            return values()
+                .find { oAuth2Type -> oAuth2Type.provider == provider }
+                ?: throw IllegalArgumentException("존재하지 않는 OAuth2 인증 타입입니다.")
+        }
+    }
+}
+

놀이터(예제 코드 작성)/spring-security/src/main/kotlin/com/banjjoknim/playground/domain/auth/OAuth2UserInfo.kt

@@ -0,0 +1,12 @@
+package com.banjjoknim.playground.domain.auth
+
+interface OAuth2UserInfo {
+
+    fun getProviderId(): String
+
+    fun getProvider(): String
+
+    fun getEmail(): String
+
+    fun getName(): String
+}

놀이터(예제 코드 작성)/spring-security/src/main/kotlin/com/banjjoknim/playground/domain/auth/OAuth2UserInfos.kt

@@ -0,0 +1,85 @@
+package com.banjjoknim.playground.domain.auth
+
+class GoogleUserInfo(
+    /**
+     * DefaultOAuth2Service#loadUser(OAuth2UserRequest)
+     * ```kotlin
+     * val oAuth2User = super.loadUser(userRequest)
+     * val attributes = oAuth2User.attributes
+     * ```
+     */
+    private val attributes: Map<String, Any?>
+) : OAuth2UserInfo {
+
+    override fun getProviderId(): String {
+        return attributes["sub"] as String
+    }
+
+    override fun getProvider(): String {
+        return "google"
+    }
+
+    override fun getEmail(): String {
+        return attributes["email"] as String
+    }
+
+    override fun getName(): String {
+        return attributes["name"] as String
+    }
+}
+
+class FacebookUserInfo(
+    /**
+     * DefaultOAuth2Service#loadUser(OAuth2UserRequest)
+     * ```kotlin
+     * val oAuth2User = super.loadUser(userRequest)
+     * val attributes = oAuth2User.attributes
+     * ```
+     */
+    private val attributes: Map<String, Any?>
+) : OAuth2UserInfo {
+    override fun getProviderId(): String {
+        return attributes["id"] as String
+    }
+
+    override fun getProvider(): String {
+        return "facebook"
+    }
+
+    override fun getEmail(): String {
+        return attributes["email"] as String
+    }
+
+    override fun getName(): String {
+        return attributes["name"] as String
+    }
+}
+
+class NaverUserInfo(
+    /**
+     * DefaultOAuth2Service#loadUser(OAuth2UserRequest)
+     * ```kotlin
+     * val oAuth2User = super.loadUser(userRequest)
+     * val attributes = oAuth2User.attributes
+     * ```
+     */
+    private val attributes: Map<String, Any?>
+): OAuth2UserInfo {
+    private val response = attributes["response"] as Map<*, *>
+
+    override fun getProviderId(): String {
+        return response["id"] as String
+    }
+
+    override fun getProvider(): String {
+        return "naver"
+    }
+
+    override fun getEmail(): String {
+        return response["email"] as String
+    }
+
+    override fun getName(): String {
+        return response["name"] as String
+    }
+}

놀이터(예제 코드 작성)/spring-security/src/main/kotlin/com/banjjoknim/playground/domain/user/User.kt

@@ -0,0 +1,19 @@
+package com.banjjoknim.playground.domain.user
+
+import javax.persistence.Entity
+import javax.persistence.GeneratedValue
+import javax.persistence.GenerationType
+import javax.persistence.Id
+
+@Entity
+class User(
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    var id: Long = 0L,
+    var username: String,
+    var password: String,
+    var email: String,
+    var role: String, // ROLE_USER, ROLE_MANAGER, ROLE_ADMIN ...
+    var provider: String,
+    var providerId: String,
+)

놀이터(예제 코드 작성)/spring-security/src/main/kotlin/com/banjjoknim/playground/domain/user/UserController.kt

@@ -0,0 +1,88 @@
+package com.banjjoknim.playground.domain.user
+
+import com.banjjoknim.playground.config.security.PrincipalDetails
+import com.banjjoknim.playground.config.security.PrincipalOAuth2UserService
+import org.springframework.security.core.Authentication
+import org.springframework.security.core.annotation.AuthenticationPrincipal
+import org.springframework.security.core.userdetails.UserDetails
+import org.springframework.security.oauth2.core.user.OAuth2User
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RestController
+class UserController {
+
+    /**
+     * ```
+     * 스프링 시큐리티는 스프링 시큐리티 세션을 들고 있다.
+     *
+     * 그러면 원래 서버 세션 영역 안에 시큐리티가 관리하는 세션이 따로 존재하게 된다.
+     *
+     * 시큐리티 세션에는 무조건 Authentication 객체 만 들어갈 수 있다.
+     *
+     * Authentication 가 시큐리티세션 안에 들어가 있다는 것은 로그인된 상태라는 의미이다.
+     *
+     * Authentication 에는 2개의 타입이 들어갈 수 있는데 UserDetails, OAuth2User 이다.
+     *
+     * 문제점 :
+     *
+     * 이때 세션이 2개의 타입으로 나눠졌기 때문에 컨트롤러에서 처리하기 복잡해진다는 문제점이 발생한다!
+     *
+     * 왜냐하면 일반적인 로그인을 할 때엔 UserDetails 타입으로 Authentication 객체가 만들어지고,
+     *
+     * 구글 로그인처럼 OAuth 로그인을 할 때엔 OAuth2User 타입으로 Authentication 객체가 만들어지기 때문이다.
+     *
+     * 해결방법 :
+     *
+     * PrincipalDetails 에 UserDetails, OAuth2User 를 implements 한다.
+     *
+     * 그렇게 하면 PrincipalDetails 타입은 UserDetails, OAuth2User 타입이 되므로 우리는 오직 PrincipalDetails 만 활용하면 된다.
+     *
+     * 추가로, @AuthenticationPrincipal 어노테이션으로 세션 정보를 DI 받아서 바로 접근할 수 있다.
+     *
+     * 이는 스프링 시큐리티가 갖고 있는 세션에서 Authentication 객체를 갖고 있기 때문이다.
+     *
+     * 그에 따라 결과적으로는 시큐리티 세션에 존재하는 Authentication 객체를 PrincipalDetails 으로 다운 캐스팅 하지 않아도 된다.
+     * ```
+     *
+     * ```
+     * @AuthenticationPrincipal 어노테이션이 활성화되는 시점?
+     *
+     * PrincipalOAuth2UserService, PrincipalDetailService 를 만들지 않아도(오버라이드 하지 않아도)
+     *
+     * loadUser(), loadUserByUsername() 은 기본적으로 실행되어 대신 스프링 시큐리티가 로그인을 진행해준다.
+     *
+     * 하지만 굳이 오버라이드 하면서 PrincipalOAuth2UserService, PrincipalDetailService 를 만든 이유는 로그인시 PrincipalDetails 객체를 반환하기 위해서다.
+     *
+     * 이는 로그인시 반환되는 객체가 Authentication 객체 내부에 저장되기 때문이며, 이렇게 하는게 더 편하다.
+     *
+     * ```
+     *
+     * @see PrincipalDetails
+     * @see AuthenticationPrincipal
+     * @see PrincipalOAuth2UserService
+     * @see PrincipalDetailsService
+     *
+     */
+    @GetMapping("/login") // OAuth2 로그인 및 일반 로그인 모두 principalDetails 로 세션 정보를 얻어올 수 있다(다운 캐스팅을 하지 않아도 된다!).
+    fun login(@AuthenticationPrincipal principalDetails: PrincipalDetails) { // DI(의존성 주입)
+        println("principalDetailsUser : ${principalDetails.user}")
+    }
+
+    @GetMapping("/test/login")
+    fun testLogin(authentication: Authentication, @AuthenticationPrincipal userDetails: UserDetails) { // DI(의존성 주입)
+        val principalDetailsFromAuthentication = authentication.principal as PrincipalDetails // 다운 캐스팅
+        println("principalDetailsFromAuthentication : ${principalDetailsFromAuthentication.user}")
+        println("principalDetailsFromAuthentication : ${principalDetailsFromAuthentication.username}")
+        val principalDetailsFromUserDetails = userDetails as PrincipalDetails // 다운 캐스팅
+        println("principalDetailsFromUserDetails : ${principalDetailsFromUserDetails.user}")
+        println("principalDetailsFromUserDetails : ${principalDetailsFromUserDetails.username}")
+    }
+
+    @GetMapping("/test/oauth2/login")
+    fun testOAuth2Login(authentication: Authentication, @AuthenticationPrincipal oauth: OAuth2User) { // DI(의존성 주입)
+        val oAuth2User = authentication.principal as OAuth2User // 다운 캐스팅
+        println("authentication : ${oAuth2User.attributes}") // OAuth2Service 의 super.loadUser(userRequest).attributes 와 같다.
+        println("oAuth2User : ${oauth.attributes}")
+    }
+}

놀이터(예제 코드 작성)/spring-security/src/main/kotlin/com/banjjoknim/playground/domain/user/UserRepository.kt

@@ -0,0 +1,7 @@
+package com.banjjoknim.playground.domain.user
+
+import org.springframework.data.jpa.repository.JpaRepository
+
+interface UserRepository : JpaRepository<User, Long> {
+    fun findByUsername(username: String): User?
+}

놀이터(예제 코드 작성)/spring-security/src/main/resources/application.yml

@@ -0,0 +1,35 @@
+spring:
+  security:
+    oauth2:
+      client:
+        registration:
+          google:
+            client-id: my-google-client-id
+            client-secret: my-google-client-secret
+            scope:
+              - email
+              - profile
+
+          facebook:
+            client-id: my-facebook-client-id
+            client-secret: my-facebook-client-secret
+            scope:
+              - email
+              - public_profile
+
+          naver:
+            client-id: my-naver-client-id
+            client-secret: my-naver-client-secret
+            scope:
+              - name
+              - email
+            client-name: Naver
+            authorization-grant-type: authorization_code
+            redirect-uri: http://localhost:8080/login/oauth2/code # 구글이나 페이스북은 기본적으로 설정되어 있기 때문에 작성하지 않아도 된다. 반면, 구글이나 페이스북은 주소가 고정되어 있으니 함부로 변경하면 안된다.
+
+        provider: # provider를 직접 등록해준다.
+          naver: # /oauth2/authorization/naver 라는 uri를 타고 이동하면 아래의 authorization-uri 로 이동된다.
+            authorization-uri: https://nid.naver.com/oauth2.0/authorize
+            token-uri: https://nid.naver.com/oauth2.0/token
+            user-info-uri: https://openapi.naver.com/v1/nid/me
+            user-name-attribute: response # 회원정보를 json으로 받는데 response라는 키값으로 네이버가 리턴해준다.

놀이터(예제 코드 작성)/spring-security/src/main/resources/static/index.html

@@ -0,0 +1,17 @@
+<head lang="ko">
+    <meta charset="utf-8">
+    <title>로그인 페이지</title>
+</head>
+<body>
+<h1>로그인 페이지</h1>
+<hr/>
+<form action="/login" method="post">
+    <input type="text" name="username" placeholder="Username"/><br/>
+    <input type="password" name="password" placeholder="Password"/><br/>
+    <button>로그인</button>
+</form>
+<a href="/oauth2/authorization/google">구글 로그인</a>
+<a href="/oauth2/authorization/facebook">페이스북 로그인</a>
+<a href="/oauth2/authorization/naver">네이버 로그인</a>
+<a href="/joinForm">회원가입을 아직 하지 않으셨나요?</a>
+</body>

놀이터(예제 코드 작성)/spring-security/src/test/kotlin/com/banjjoknim/playground/SpringSecurityApplicationTests.kt

@@ -0,0 +1,13 @@
+package com.banjjoknim.playground
+
+import org.junit.jupiter.api.Test
+import org.springframework.boot.test.context.SpringBootTest
+
+@SpringBootTest
+class SpringSecurityApplicationTests {
+
+	@Test
+	fun contextLoads() {
+	}
+
+}