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/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
* ================================================================================
* 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.
* ============LICENSE_END=========================================================
*/
package org.onap.policy.common.gson;
import com.google.gson.Gson;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.nio.charset.StandardCharsets;
import javax.ws.rs.Consumes;
import javax.ws.rs.Produces;
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 org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Provider that serializes and de-serializes JSON via gson.
*/
@Provider
@Consumes(MediaType.WILDCARD)
@Produces(MediaType.WILDCARD)
public class GsonMessageBodyHandler implements MessageBodyReader<Object>, MessageBodyWriter<Object> {
public static final Logger logger = LoggerFactory.getLogger(GsonMessageBodyHandler.class);
/**
* Object to be used to serialize and de-serialize.
*/
private Gson gson;
/**
* Constructs the object, using a plain Gson object.
*/
public GsonMessageBodyHandler() {
this(new Gson());
logger.info("Using GSON for REST calls");
}
/**
* Constructs the object.
*
* @param gson the Gson object to be used to serialize and de-serialize
*/
public GsonMessageBodyHandler(Gson gson) {
this.gson = gson;
}
@Override
public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
return canHandle(mediaType);
}
@Override
public long getSize(Object object, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
return -1;
}
@Override
public void writeTo(Object object, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType,
MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream)
throws IOException {
try (OutputStreamWriter writer = new OutputStreamWriter(entityStream, StandardCharsets.UTF_8)) {
Type jsonType = (type.equals(genericType) ? type : genericType);
gson.toJson(object, jsonType, writer);
}
}
@Override
public boolean isReadable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
return canHandle(mediaType);
}
/**
* Determines if this provider can handle the given media type.
*
* @param mediaType the media type of interest
* @return {@code true} if this provider handles the given media type, {@code false}
* otherwise
*/
private boolean canHandle(MediaType mediaType) {
if (mediaType == null) {
return true;
}
String subtype = mediaType.getSubtype();
if ("json".equalsIgnoreCase(subtype) || "javascript".equals(subtype)) {
return true;
}
return subtype.endsWith("+json") || "x-json".equals(subtype) || "x-javascript".equals(subtype);
}
@Override
public Object readFrom(Class<Object> type, Type genericType, Annotation[] annotations, MediaType mediaType,
MultivaluedMap<String, String> httpHeaders, InputStream entityStream)
throws IOException {
try (InputStreamReader streamReader = new InputStreamReader(entityStream, StandardCharsets.UTF_8)) {
Type jsonType = (type.equals(genericType) ? type : genericType);
return gson.fromJson(streamReader, jsonType);
}
}
}
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