JsonRawProvider.java

package com.devicehive.resource.converters;

/*
 * #%L
 * DeviceHive Java Server Common business logic
 * %%
 * Copyright (C) 2016 DataArt
 * %%
 * 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
 * 
 *      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.
 * #L%
 */


import com.devicehive.configuration.Messages;
import com.devicehive.json.GsonFactory;
import com.google.gson.Gson;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

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 java.nio.charset.Charset;

import static com.devicehive.configuration.Constants.UTF8;

@Provider
public class JsonRawProvider implements MessageBodyWriter<JsonObject>, MessageBodyReader<JsonObject> {

    @Override
    public boolean isReadable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return MediaType.APPLICATION_JSON_TYPE.getType().equals(mediaType.getType()) && MediaType
            .APPLICATION_JSON_TYPE.getSubtype().equals(mediaType.getSubtype());
    }

    @Override
    public JsonObject readFrom(Class<JsonObject> type, Type genericType, Annotation[] annotations, MediaType mediaType,
                               MultivaluedMap<String, String> httpHeaders, InputStream entityStream)
        throws IOException, WebApplicationException {
        JsonElement element = new JsonParser().parse(new InputStreamReader(entityStream, Charset.forName(UTF8)));
        if (element.isJsonObject()) {
            return element.getAsJsonObject();
        }
        throw new IOException(Messages.NOT_A_JSON_OBJECT);
    }

    @Override
    public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
        return MediaType.APPLICATION_JSON_TYPE.getType().equals(mediaType.getType()) && MediaType
            .APPLICATION_JSON_TYPE.getSubtype().equals(mediaType.getSubtype());
    }

    @Override
    public long getSize(JsonObject jsonObject, Class<?> type, Type genericType, Annotation[] annotations,
                        MediaType mediaType) {
        return 0;
    }

    @Override
    public void writeTo(JsonObject jsonObject, Class<?> type, Type genericType, Annotation[] annotations,
                        MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream)
        throws IOException, WebApplicationException {
        Gson gson = GsonFactory.createGson();
        Writer writer = null;
        try {
            writer = new OutputStreamWriter(entityStream, Charset.forName(UTF8));
            gson.toJson(jsonObject, writer);
        } finally {
            if (writer != null) {
                writer.flush();
            }
        }
    }
}