# GsonMessageBodyHandler.java

    /*
     * Copyright (c) 2017, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
     *
     * WSO2 Inc. licenses this file to you 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
     *
     * http://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.wso2.carbon.mdm.services.android.common;

    import com.google.gson.Gson;
    import com.google.gson.GsonBuilder;

    import javax.ws.rs.Consumes;
    import javax.ws.rs.Produces;
    import javax.ws.rs.WebApplicationException;
    import javax.ws.rs.core.MediaType;
    import javax.ws.rs.core.MultivaluedMap;
    import javax.ws.rs.ext.MessageBodyReader;
    import javax.ws.rs.ext.MessageBodyWriter;
    import javax.ws.rs.ext.Provider;

    import java.io.*;
    import java.lang.annotation.Annotation;
    import java.lang.reflect.Type;

    import static javax.ws.rs.core.MediaType.APPLICATION_JSON;

    @Provider
    @Produces(APPLICATION_JSON)
    @Consumes(APPLICATION_JSON)
    public class GsonMessageBodyHandler implements MessageBodyWriter<Object>, MessageBodyReader<Object> {

        private Gson gson;
        private static final String UTF_8 = "UTF-8";

        public boolean isReadable(Class<?> aClass, Type type, Annotation[] annotations, MediaType mediaType) {
            return true;
        }

        private Gson getGson() {
            if (gson == null) {
                final GsonBuilder gsonBuilder = new GsonBuilder();
                gson = gsonBuilder.create();
            }
            return gson;
        }

        public Object readFrom(Class<Object> objectClass, Type type, Annotation[] annotations, MediaType mediaType,
                MultivaluedMap<String, String> stringStringMultivaluedMap, InputStream entityStream)
                throws IOException, WebApplicationException {

            InputStreamReader reader = new InputStreamReader(entityStream, "UTF-8");

            try {
                return getGson().fromJson(reader, type);
            } finally {
                reader.close();
            }
        }

        public boolean isWriteable(Class<?> aClass, Type type, Annotation[] annotations, MediaType mediaType) {
            return true;
        }

        public long getSize(Object o, Class<?> aClass, Type type, Annotation[] annotations, MediaType mediaType) {
            return -1;
        }

        public void writeTo(Object object, Class<?> aClass, Type type, Annotation[] annotations, MediaType mediaType,
                MultivaluedMap<String, Object> stringObjectMultivaluedMap, OutputStream entityStream)
                throws IOException, WebApplicationException {

            OutputStreamWriter writer = new OutputStreamWriter(entityStream, UTF_8);
            try {
                getGson().toJson(object, type, writer);
            } finally {
                writer.close();
            }
        }
    }