001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package org.apache.hadoop.lib.wsrs;
020    
021    import org.apache.hadoop.classification.InterfaceAudience;
022    import org.json.simple.JSONStreamAware;
023    
024    import javax.ws.rs.Produces;
025    import javax.ws.rs.WebApplicationException;
026    import javax.ws.rs.core.MediaType;
027    import javax.ws.rs.core.MultivaluedMap;
028    import javax.ws.rs.ext.MessageBodyWriter;
029    import javax.ws.rs.ext.Provider;
030    import java.io.IOException;
031    import java.io.OutputStream;
032    import java.io.OutputStreamWriter;
033    import java.io.Writer;
034    import java.lang.annotation.Annotation;
035    import java.lang.reflect.Type;
036    
037    @Provider
038    @Produces(MediaType.APPLICATION_JSON)
039    @InterfaceAudience.Private
040    public class JSONProvider implements MessageBodyWriter<JSONStreamAware> {
041      private static final String ENTER = System.getProperty("line.separator");
042    
043      @Override
044      public boolean isWriteable(Class<?> aClass, Type type, Annotation[] annotations, MediaType mediaType) {
045        return JSONStreamAware.class.isAssignableFrom(aClass);
046      }
047    
048      @Override
049      public long getSize(JSONStreamAware jsonStreamAware, Class<?> aClass, Type type, Annotation[] annotations,
050                          MediaType mediaType) {
051        return -1;
052      }
053    
054      @Override
055      public void writeTo(JSONStreamAware jsonStreamAware, Class<?> aClass, Type type, Annotation[] annotations,
056                          MediaType mediaType, MultivaluedMap<String, Object> stringObjectMultivaluedMap,
057                          OutputStream outputStream) throws IOException, WebApplicationException {
058        Writer writer = new OutputStreamWriter(outputStream);
059        jsonStreamAware.writeJSONString(writer);
060        writer.write(ENTER);
061        writer.flush();
062      }
063    
064    }