BAEL-1778 (#4351)

* Also needed

* BAEL-1698

* BAEL-1698

* BAEL-1778

gson/pom.xml

@@ -1,4 +1,5 @@
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>com.baeldung</groupId>
@@ -15,6 +16,12 @@
 
 	<dependencies>
 		<!-- utils -->
+		<dependency>
+			<groupId>org.projectlombok</groupId>
+			<artifactId>lombok</artifactId>
+			<version>1.16.10</version>
+			<scope>provided</scope>
+		</dependency>
 		<dependency>
 			<groupId>joda-time</groupId>
 			<artifactId>joda-time</artifactId>

gson/src/main/java/org/baeldung/gson/serializationwithexclusions/Exclude.java

@@ -0,0 +1,11 @@
+package org.baeldung.gson.serializationwithexclusions;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.FIELD)
+public @interface Exclude {
+}

gson/src/main/java/org/baeldung/gson/serializationwithexclusions/MyClass.java

@@ -0,0 +1,13 @@
+package org.baeldung.gson.serializationwithexclusions;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class MyClass {
+    private long id;
+    private String name;
+    private String other;
+    private MySubClass subclass;
+}

gson/src/main/java/org/baeldung/gson/serializationwithexclusions/MyClassWithAnnotatedFields.java

@@ -0,0 +1,20 @@
+package org.baeldung.gson.serializationwithexclusions;
+
+import com.google.gson.annotations.Expose;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class MyClassWithAnnotatedFields {
+
+    @Expose
+    private long id;
+    @Expose
+    private String name;
+    private String other;
+    @Expose
+    private MySubClassWithAnnotatedFields subclass;
+
+}

gson/src/main/java/org/baeldung/gson/serializationwithexclusions/MyClassWithCustomAnnotatedFields.java

@@ -0,0 +1,16 @@
+package org.baeldung.gson.serializationwithexclusions;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class MyClassWithCustomAnnotatedFields {
+
+    private long id;
+    private String name;
+    @Exclude
+    private String other;
+    private MySubClassWithCustomAnnotatedFields subclass;
+
+}

gson/src/main/java/org/baeldung/gson/serializationwithexclusions/MyClassWithTransientFields.java

@@ -0,0 +1,15 @@
+package org.baeldung.gson.serializationwithexclusions;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class MyClassWithTransientFields {
+
+    private long id;
+    private String name;
+    private transient String other;
+    private MySubClassWithTransientFields subclass;
+
+}

gson/src/main/java/org/baeldung/gson/serializationwithexclusions/MySubClass.java

@@ -0,0 +1,12 @@
+package org.baeldung.gson.serializationwithexclusions;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class MySubClass {
+    private long id;
+    private String description;
+    private String otherVerboseInfo;
+}

gson/src/main/java/org/baeldung/gson/serializationwithexclusions/MySubClassWithAnnotatedFields.java

@@ -0,0 +1,15 @@
+package org.baeldung.gson.serializationwithexclusions;
+
+import com.google.gson.annotations.Expose;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class MySubClassWithAnnotatedFields {
+
+    @Expose private long id;
+    @Expose private String description;
+    private String otherVerboseInfo;
+}

gson/src/main/java/org/baeldung/gson/serializationwithexclusions/MySubClassWithCustomAnnotatedFields.java

@@ -0,0 +1,14 @@
+package org.baeldung.gson.serializationwithexclusions;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class MySubClassWithCustomAnnotatedFields {
+
+    private long id;
+    private String description;
+    @Exclude 
+    private String otherVerboseInfo;
+}

gson/src/main/java/org/baeldung/gson/serializationwithexclusions/MySubClassWithTransientFields.java

@@ -0,0 +1,13 @@
+package org.baeldung.gson.serializationwithexclusions;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+@Data
+@AllArgsConstructor
+public class MySubClassWithTransientFields {
+
+    private long id;
+    private String description;
+    private transient String otherVerboseInfo;
+}

gson/src/test/java/org/baeldung/gson/serializationwithexclusions/SerializationWithExclusionsUnitTest.java

@@ -0,0 +1,104 @@
+package org.baeldung.gson.serializationwithexclusions;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+import com.google.gson.ExclusionStrategy;
+import com.google.gson.FieldAttributes;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+
+class SerializationWithExclusionsUnitTest {
+
+    final String expectedResult = "{\"id\":1,\"name\":\"foo\",\"subclass\":{\"id\":42,\"description\":\"the answer\"}}";
+
+    @Test
+    public void givenClassWithTransientFields_whenSerializing_thenCorrectWithoutTransientFields() {
+        MyClassWithTransientFields source = new MyClassWithTransientFields(1L, "foo", "bar", new MySubClassWithTransientFields(42L, "the answer", "Verbose field which we don't want to be serialized"));
+        String jsonString = new Gson().toJson(source);
+        assertEquals(expectedResult, jsonString);
+    }
+
+    @Test
+    public void givenClassAnnotated_whenSerializing_thenCorrectWithoutNotAnnotatedFields() {
+        MyClassWithAnnotatedFields source = new MyClassWithAnnotatedFields(1L, "foo", "bar", new MySubClassWithAnnotatedFields(42L, "the answer", "Verbose field which we don't want to be serialized"));
+        Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation()
+            .create();
+        String jsonString = gson.toJson(source);
+
+        assertEquals(expectedResult, jsonString);
+    }
+
+    @Test
+    public void givenExclusionStrategyByClassesAndFields_whenSerializing_thenFollowStrategy() {
+        MyClass source = new MyClass(1L, "foo", "bar", new MySubClass(42L, "the answer", "Verbose field which we don't want to be serialized"));
+        ExclusionStrategy strategy = new ExclusionStrategy() {
+            @Override
+            public boolean shouldSkipField(FieldAttributes field) {
+                if (field.getDeclaringClass() == MyClass.class && field.getName()
+                    .equals("other"))
+                    return true;
+                if (field.getDeclaringClass() == MySubClass.class && field.getName()
+                    .equals("otherVerboseInfo"))
+                    return true;
+                return false;
+            }
+
+            @Override
+            public boolean shouldSkipClass(Class<?> clazz) {
+                return false;
+            }
+        };
+
+        Gson gson = new GsonBuilder().addSerializationExclusionStrategy(strategy)
+            .create();
+        String jsonString = gson.toJson(source);
+
+        assertEquals(expectedResult, jsonString);
+    }
+
+    @Test
+    public void givenExclusionStrategyByStartsWith_whenSerializing_thenFollowStrategy() {
+        MyClass source = new MyClass(1L, "foo", "bar", new MySubClass(42L, "the answer", "Verbose field which we don't want to be serialized"));
+        ExclusionStrategy strategy = new ExclusionStrategy() {
+            @Override
+            public boolean shouldSkipClass(Class<?> clazz) {
+                return false;
+            }
+
+            @Override
+            public boolean shouldSkipField(FieldAttributes field) {
+                return field.getName().startsWith("other");
+            }
+        };
+        Gson gson = new GsonBuilder().setExclusionStrategies(strategy)
+            .create();
+        String jsonString = gson.toJson(source);
+
+        assertEquals(expectedResult, jsonString);
+    }
+
+    @Test
+    public void givenExclusionStrategyByCustomAnnotation_whenSerializing_thenFollowStrategy() {
+        MyClassWithCustomAnnotatedFields source = new MyClassWithCustomAnnotatedFields(1L, "foo", "bar", new MySubClassWithCustomAnnotatedFields(42L, "the answer", "Verbose field which we don't want to be serialized"));
+        ExclusionStrategy strategy = new ExclusionStrategy() {
+            @Override
+            public boolean shouldSkipClass(Class<?> clazz) {
+                return false;
+            }
+
+            @Override
+            public boolean shouldSkipField(FieldAttributes field) {
+                return field.getAnnotation(Exclude.class) != null;
+            }
+
+        };
+
+        Gson gson = new GsonBuilder().setExclusionStrategies(strategy)
+            .create();
+        String jsonString = gson.toJson(source);
+        assertEquals(expectedResult, jsonString);
+    }
+
+}