gson serialization work

Author: eugenp

gson/src/test/java/org/baeldung/gson/serialization/GsonSerializationTest.java

@@ -0,0 +1,64 @@
+package org.baeldung.gson.serialization;
+
+import static org.junit.Assert.assertEquals;
+
+import java.lang.reflect.Type;
+import java.util.Collection;
+
+import org.junit.Test;
+
+import com.google.common.collect.Lists;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.reflect.TypeToken;
+
+public class GsonSerializationTest {
+
+    @Test
+    public void givenCollection_whenSerializing_thenCorrect() {
+        final Collection<SourceClass> sourceCollection = Lists.newArrayList(new SourceClass(1, "one"), new SourceClass(2, "two"));
+        final Type sourceCollectionType = new TypeToken<Collection<SourceClass>>() {
+        }.getType();
+        final String jsonCollection = new Gson().toJson(sourceCollection, sourceCollectionType);
+
+        // test
+        final Collection<SourceClass> testCollection = new Gson().fromJson(jsonCollection, sourceCollectionType);
+        assertEquals(sourceCollection, testCollection);
+    }
+
+    @Test
+    public void givenArrayOfObjects_whenSerializing_thenMapToJsonCollection() {
+        final SourceClass[] sourceArray = { new SourceClass(1, "one"), new SourceClass(2, "two") };
+        final String jsonCollection = new Gson().toJson(sourceArray);
+
+        // test
+        final String estimatedResult = "[{\"intValue\":1,\"stringValue\":\"one\"},{\"intValue\":2,\"stringValue\":\"two\"}]";
+        assertEquals(estimatedResult, jsonCollection);
+    }
+
+    @Test
+    public void givenUsingCustomSerializer_whenSerializingObjectToJsonWithDissimilarFieldNames_thenCorrect() {
+        final SourceClass sourceObject = new SourceClass(7, "seven");
+        final GsonBuilder gsonBuildr = new GsonBuilder();
+        gsonBuildr.registerTypeAdapter(SourceClass.class, new SourceClassChangingFieldNamesSerializer());
+        final Gson gson = gsonBuildr.create();
+        final String jsonString = gson.toJson(sourceObject);
+
+        // test
+        final String estimatedResult = "{\"otherIntValue\":7,\"otherStringValue\":\"seven\"}";
+        assertEquals(estimatedResult, jsonString);
+    }
+
+    @Test
+    public void givenUsingCustomSerializer_whenSerializingObject_thenFieldIgnored() {
+        final SourceClass sourceObject = new SourceClass(7, "seven");
+        final GsonBuilder gsonBuildr = new GsonBuilder();
+        gsonBuildr.registerTypeAdapter(SourceClass.class, new SourceClassIgnoringExtraFieldsSerializer());
+        final Gson gson = gsonBuildr.create();
+        final String jsonString = gson.toJson(sourceObject);
+
+        // test
+        final String estimatedResult = "{\"intValue\":7}";
+        assertEquals(estimatedResult, jsonString);
+    }
+}

gson/src/test/java/org/baeldung/gson/serialization/SourceClass.java

@@ -0,0 +1,45 @@
+package org.baeldung.gson.serialization;
+
+public class SourceClass {
+    public int intValue;
+    public String stringValue;
+
+    public SourceClass(final int intValue, final String stringValue) {
+        this.intValue = intValue;
+        this.stringValue = stringValue;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + intValue;
+        result = prime * result + ((stringValue == null) ? 0 : stringValue.hashCode());
+        return result;
+    }
+
+    @Override
+    public boolean equals(final Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        final SourceClass other = (SourceClass) obj;
+        if (intValue != other.intValue)
+            return false;
+        if (stringValue == null) {
+            if (other.stringValue != null)
+                return false;
+        } else if (!stringValue.equals(other.stringValue))
+            return false;
+        return true;
+    }
+
+    @Override
+    public String toString() {
+        return "SourceClass{" + "intValue=" + intValue + ", stringValue='" + stringValue + '\'' + '}';
+    }
+
+}

gson/src/test/java/org/baeldung/gson/serialization/SourceClassChangingFieldNamesSerializer.java

@@ -0,0 +1,24 @@
+package org.baeldung.gson.serialization;
+
+import java.lang.reflect.Type;
+
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonSerializationContext;
+import com.google.gson.JsonSerializer;
+
+public class SourceClassChangingFieldNamesSerializer implements JsonSerializer<SourceClass> {
+
+    @Override
+    public JsonElement serialize(final SourceClass src, final Type typeOfSrc, final JsonSerializationContext context) {
+        final String otherIntValueName = "otherIntValue";
+        final String otherStringValueName = "otherStringValue";
+
+        final JsonObject jObject = new JsonObject();
+        jObject.addProperty(otherIntValueName, src.intValue);
+        jObject.addProperty(otherStringValueName, src.stringValue);
+
+        return jObject;
+    }
+
+}

gson/src/test/java/org/baeldung/gson/serialization/SourceClassIgnoringExtraFieldsSerializer.java

@@ -0,0 +1,21 @@
+package org.baeldung.gson.serialization;
+
+import java.lang.reflect.Type;
+
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonSerializationContext;
+import com.google.gson.JsonSerializer;
+
+public class SourceClassIgnoringExtraFieldsSerializer implements JsonSerializer<SourceClass> {
+
+    @Override
+    public JsonElement serialize(final SourceClass src, final Type typeOfSrc, final JsonSerializationContext context) {
+        final String intValue = "intValue";
+        final JsonObject jObject = new JsonObject();
+        jObject.addProperty(intValue, src.intValue);
+
+        return jObject;
+    }
+
+}