feat : 어노테이션 기반의 직렬화 예제 코드 추가

2022-03-13 20:41:52 +09:00
parent abcf7da69e
commit 9f9a5644fc
6 changed files with 122 additions and 17 deletions
--- a/작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/common/Car.kt
+++ b/작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/common/Car.kt
@@ -1,7 +0,0 @@
-package com.banjjoknim.playground.jackson.common
-
-data class Car(
-    val name: String,
-    val price: Int = 0,
-    val owner: Owner
-)
--- a/작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/common/Cars.kt
+++ b/작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/common/Cars.kt
@@ -0,0 +1,33 @@
+package com.banjjoknim.playground.jackson.common
+
+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 CarUsingJsonSerializeAnnotation(
+    val name: String = "banjjoknim",
+    @JsonSerialize(using = UsingJsonSerializeAnnotationCarSerializer::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()
+)
--- a/작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/common/Owner.kt
+++ b/작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/common/Owner.kt
@@ -1,3 +1,3 @@
 package com.banjjoknim.playground.jackson.common

-data class Owner(val name: String, val age: Int)
+data class Owner(val name: String = "ban", val age: Int = 30)
--- a/작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/common/Secret.kt
+++ b/작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/common/Secret.kt
@@ -9,6 +9,6 @@ import com.fasterxml.jackson.annotation.JacksonAnnotation
 * @see com.fasterxml.jackson.annotation.JacksonAnnotationsInside
 */
@Retention(AnnotationRetention.RUNTIME)
-@Target(AnnotationTarget.PROPERTY)
-@JacksonAnnotation // Jackson 에서 이 어노테이션을 인식할 수 있게 만들어준다.
+@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
--- a/작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/jsonserialize/CarSerializers.kt
+++ b/작성)/jackson/src/main/kotlin/com/banjjoknim/playground/jackson/jsonserialize/CarSerializers.kt
@@ -1,8 +1,12 @@
 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.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.ser.std.StdSerializer

 /**
@@ -16,9 +20,12 @@ import com.fasterxml.jackson.databind.ser.std.StdSerializer
 *
 * 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) {
@@ -64,3 +71,40 @@ class CarNameOwnerNameSerializer : StdSerializer<Car>(Car::class.java) {
        gen.writeEndObject()
    }
 }
+
+class UsingJsonSerializeAnnotationCarSerializer : StdSerializer<String>(String::class.java) {
+    override fun serialize(value: String, gen: JsonGenerator, provider: SerializerProvider) {
+        gen.writeString("****")
+    }
+}
+
+class SecretAnnotationSerializer : StdSerializer<String>(String::class.java) {
+    override fun serialize(value: String, gen: JsonGenerator, provider: SerializerProvider) {
+        gen.writeString("****")
+    }
+}
+
+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)
+    }
+
+    /**
+     * 특정 프로퍼티에 대해 어떤 Serializer 를 사용할 것인지 결정하는 함수이다.
+     *
+     * 따라서 특정 조건에 따라 직렬화를 하고싶다면 이 함수를 override 하면 된다.
+     */
+    override fun findSerializer(a: Annotated): Any? {
+        val annotation = a.getAnnotation(Secret::class.java)
+        if (annotation != null) {
+            return SecretAnnotationSerializer()
+        }
+        return super.findSerializer(a) // 기존 JacksonAnnotationIntrospector 의 것을 사용한다.
+    }
+}
--- a/작성)/jackson/src/test/kotlin/com/banjjoknim/playground/jackson/jsonserialize/CarSerializersTest.kt
+++ b/작성)/jackson/src/test/kotlin/com/banjjoknim/playground/jackson/jsonserialize/CarSerializersTest.kt
@@ -1,11 +1,9 @@
-package com.banjjoknim.playground.jsonserialize
+package com.banjjoknim.playground.jackson.jsonserialize

-import com.banjjoknim.playground.jackson.jsonserialize.CarNameOwnerNameSerializer
-import com.banjjoknim.playground.jackson.jsonserialize.CarNameOwnerSerializer
-import com.banjjoknim.playground.jackson.jsonserialize.CarNameSerializer
-import com.banjjoknim.playground.jackson.jsonserialize.CarPriceSerializer
-import com.banjjoknim.playground.jackson.jsonserialize.CarSerializer
 import com.banjjoknim.playground.jackson.common.Car
+import com.banjjoknim.playground.jackson.common.CarUsingJsonSerializeAnnotation
+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.ObjectMapper
 import com.fasterxml.jackson.databind.module.SimpleModule
@@ -25,13 +23,16 @@ import org.junit.jupiter.api.Test
 * @see com.fasterxml.jackson.databind.ser.std.BeanSerializerBase
 * @see com.fasterxml.jackson.databind.ser.BeanPropertyWriter
 */
-class CarSerializerTest {
+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 carUsingJsonSerializeAnnotation = CarUsingJsonSerializeAnnotation()
+        private val carUsingSecretAnnotation = CarUsingSecretAnnotation()
    }

    @BeforeEach
@@ -122,5 +123,39 @@ class CarSerializerTest {
            // 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(carUsingJsonSerializeAnnotation)
+
+            // then
+            assertThat(actual).isEqualTo("""{"name":"banjjoknim","secret":"****","price":10000000,"owner":{"name":"ban","age":30}}""")
+        }
+
+        @Test
+        fun `@Secret 어노테이션을 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}}""")
+        }
    }
 }