#23 di: di practice

my-framework/di-practice/build.gradle

@@ -0,0 +1,23 @@
+plugins {
+    id 'java'
+}
+
+group 'org.example'
+version '1.0-SNAPSHOT'
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation 'org.reflections:reflections:0.10.2'
+
+    testImplementation 'org.assertj:assertj-core:3.22.0'
+
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.1'
+    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.8.1'
+}
+
+test {
+    useJUnitPlatform()
+}

my-framework/di-practice/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.4-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

my-framework/di-practice/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 "$JAVACMD" "$@"

my-framework/di-practice/gradlew.bat

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+@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

my-framework/di-practice/settings.gradle

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+rootProject.name = 'di-practice'
+

my-framework/di-practice/src/main/java/org/example/Main.java

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+package org.example;
+
+public class Main {
+}

my-framework/di-practice/src/main/java/org/example/annotation/Controller.java

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+package org.example.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Controller {
+}

my-framework/di-practice/src/main/java/org/example/annotation/Inject.java

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+package org.example.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.METHOD, ElementType.CONSTRUCTOR, ElementType.FIELD})
+@Retention(RetentionPolicy. RUNTIME)
+public @interface Inject {
+}

my-framework/di-practice/src/main/java/org/example/annotation/Repository.java

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+package org.example.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Repository {
+}

my-framework/di-practice/src/main/java/org/example/annotation/Service.java

@@ -0,0 +1,11 @@
+package org.example.annotation;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Service {
+}

my-framework/di-practice/src/main/java/org/example/controller/UserController.java

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+package org.example.controller;
+
+import org.example.annotation.Controller;
+import org.example.annotation.Inject;
+import org.example.service.UserService;
+
+@Controller
+public class UserController {
+
+    private final UserService userService;
+
+    @Inject
+    public UserController(UserService userService) {
+        this.userService = userService;
+    }
+
+    public UserService getUserService() {
+        return userService;
+    }
+}

my-framework/di-practice/src/main/java/org/example/di/BeanFactory.java

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+package org.example.di;
+
+import org.example.annotation.Inject;
+import org.reflections.ReflectionUtils;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.util.*;
+
+public class BeanFactory {
+
+    private final Set<Class<?>> preInstantiatedClass;
+    private final Map<Class<?>, Object> beans = new HashMap<>();
+
+    public BeanFactory(Set<Class<?>> preInstantiatedClass) {
+        this.preInstantiatedClass = preInstantiatedClass;
+        initialize();
+    }
+
+    private void initialize() {
+        for (Class<?> clazz : preInstantiatedClass) {
+            Object instance = createInstance(clazz);
+            beans.put(clazz, instance);
+        }
+    }
+
+    private Object createInstance(Class<?> clazz) {
+        Constructor<?> constructor = findConstructor(clazz);
+
+        List<Object> parameters = new ArrayList<>();
+
+        for (Class<?> typeClass : constructor.getParameterTypes()) {
+            parameters.add(getParameterByClass(typeClass));
+        }
+
+        try {
+            return constructor.newInstance(parameters.toArray());
+        } catch (InstantiationException | IllegalAccessException | InvocationTargetException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+
+    private Constructor<?> findConstructor(Class<?> clazz) {
+        Constructor<?> constructor = BeanFactoryUtils.getInjectedConstructor(clazz);
+
+        if (Objects.nonNull(constructor)) {
+            return constructor;
+        }
+
+        return clazz.getConstructors()[0];
+    }
+
+    private Object getParameterByClass(Class<?> typeClass) {
+        Object instanceBean = getBean(typeClass);
+
+        if (Objects.nonNull(instanceBean)){
+            return instanceBean;
+        }
+
+        return createInstance(typeClass);
+    }
+
+    public <T> T getBean(Class<T> requiredType) {
+        return (T) beans.get(requiredType);
+    }
+}

my-framework/di-practice/src/main/java/org/example/di/BeanFactoryUtils.java

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+package org.example.di;
+
+import org.example.annotation.Inject;
+import org.reflections.ReflectionUtils;
+
+import java.lang.reflect.Constructor;
+import java.util.Set;
+
+public class BeanFactoryUtils {
+
+    public static Constructor<?> getInjectedConstructor(Class<?> clazz) {
+        Set<Constructor> injectedConstructor = ReflectionUtils.getAllConstructors(clazz, ReflectionUtils.withAnnotation(Inject.class));
+
+        if (injectedConstructor.isEmpty()) {
+            return null;
+        }
+
+        return injectedConstructor.iterator().next();
+    }
+}

my-framework/di-practice/src/main/java/org/example/repository/UserRepository.java

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+package org.example.repository;
+
+import org.example.annotation.Repository;
+
+@Repository
+public class UserRepository {
+}

my-framework/di-practice/src/main/java/org/example/service/UserService.java

@@ -0,0 +1,20 @@
+package org.example.service;
+
+import org.example.annotation.Inject;
+import org.example.annotation.Service;
+import org.example.repository.UserRepository;
+
+@Service
+public class UserService {
+
+    private final UserRepository userRepository;
+
+    @Inject
+    public UserService(UserRepository userRepository) {
+        this.userRepository = userRepository;
+    }
+
+    public UserRepository getUserRepository() {
+        return userRepository;
+    }
+}

my-framework/di-practice/src/test/java/org/example/di/BeanFactoryTest.java

@@ -0,0 +1,49 @@
+package org.example.di;
+
+import org.assertj.core.api.Assertions;
+import org.example.annotation.Controller;
+import org.example.annotation.Repository;
+import org.example.annotation.Service;
+import org.example.controller.UserController;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.reflections.Reflections;
+
+import java.lang.annotation.Annotation;
+import java.util.HashSet;
+import java.util.Set;
+
+import static org.assertj.core.api.Assertions.*;
+
+class BeanFactoryTest {
+
+    private Reflections reflections;
+    private BeanFactory beanFactory;
+
+    @BeforeEach
+    void setUp() {
+        reflections = new Reflections("org.example");
+        Set<Class<?>> preInstantiatedClass = getTypesAnnotatedWith(Controller.class, Service.class, Repository.class);
+        beanFactory = new BeanFactory(preInstantiatedClass);
+
+    }
+
+    private Set<Class<?>> getTypesAnnotatedWith(Class<? extends Annotation>... annotations) {
+        Set<Class<?>> beans = new HashSet<>();
+
+        for (Class<? extends Annotation> annotation : annotations) {
+            beans.addAll(reflections.getTypesAnnotatedWith(annotation));
+        }
+
+        return beans;
+    }
+
+    @Test
+    void diTest() {
+        UserController userController = beanFactory.getBean(UserController.class);
+
+        assertThat(userController).isNotNull();
+        assertThat(userController.getUserService()).isNotNull();
+        assertThat(userController.getUserService().getUserRepository()).isNotNull();
+    }
+}