/*
 * Copyright 2002-2017 the original author or 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.
 */

package org.springframework.http.converter.json;

import java.lang.reflect.Type;

import com.google.gson.GsonBuilder;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonPrimitive;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;

import org.springframework.util.Base64Utils;

A simple utility class for obtaining a Google Gson 2.x GsonBuilder which Base64-encodes byte[] properties when reading and writing JSON.
Author:Juergen Hoeller, Roy Clarkson
See Also:
Since:4.1
/** * A simple utility class for obtaining a Google Gson 2.x {@link GsonBuilder} * which Base64-encodes {@code byte[]} properties when reading and writing JSON. * * @author Juergen Hoeller * @author Roy Clarkson * @since 4.1 * @see GsonFactoryBean#setBase64EncodeByteArrays * @see org.springframework.util.Base64Utils */
public abstract class GsonBuilderUtils {
Obtain a GsonBuilder which Base64-encodes byte[] properties when reading and writing JSON.

A custom TypeAdapter will be registered via registerTypeHierarchyAdapter.registerTypeHierarchyAdapter(Class, Object) which serializes a byte[] property to and from a Base64-encoded String instead of a JSON array.

/** * Obtain a {@link GsonBuilder} which Base64-encodes {@code byte[]} * properties when reading and writing JSON. * <p>A custom {@link com.google.gson.TypeAdapter} will be registered via * {@link GsonBuilder#registerTypeHierarchyAdapter(Class, Object)} which * serializes a {@code byte[]} property to and from a Base64-encoded String * instead of a JSON array. */
public static GsonBuilder gsonBuilderWithBase64EncodedByteArrays() { GsonBuilder builder = new GsonBuilder(); builder.registerTypeHierarchyAdapter(byte[].class, new Base64TypeAdapter()); return builder; } private static class Base64TypeAdapter implements JsonSerializer<byte[]>, JsonDeserializer<byte[]> { @Override public JsonElement serialize(byte[] src, Type typeOfSrc, JsonSerializationContext context) { return new JsonPrimitive(Base64Utils.encodeToString(src)); } @Override public byte[] deserialize(JsonElement json, Type type, JsonDeserializationContext cxt) { return Base64Utils.decodeFromString(json.getAsString()); } } }