utils/rest/src/main/java/org/onlab/rest/JsonBodyWriter.java

/*
 * Copyright 2015-present Open Networking Laboratory
 *
 * 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.
 */

package org.onlab.rest;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;

import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;
import java.io.IOException;
import java.io.OutputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;

/**
 * JAX-RS Response message body writer.
 */
@Provider
@Produces("application/json")
public class JsonBodyWriter implements MessageBodyWriter<ObjectNode> {

    private ObjectMapper mapper = new ObjectMapper();

    @Override
    public boolean isWriteable(Class<?> type, Type genericType,
                               Annotation[] annotations, MediaType mediaType) {
        return type == ObjectNode.class;
    }

    @Override
    public long getSize(ObjectNode node, Class<?> type, Type genericType,
                        Annotation[] annotations, MediaType mediaType) {
        return -1;
    }

    @Override
    public void writeTo(ObjectNode node, Class<?> type, Type genericType,
                        Annotation[] annotations, MediaType mediaType,
                        MultivaluedMap<String, Object> httpHeaders,
                        OutputStream entityStream) throws IOException {
        mapper.writer().writeValue(entityStream, node);
        entityStream.flush();
    }
}