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.io.serializer;
020    
021    import java.io.IOException;
022    import java.io.InputStream;
023    import java.io.ObjectInputStream;
024    import java.io.ObjectOutputStream;
025    import java.io.OutputStream;
026    import java.io.Serializable;
027    import java.util.Map;
028    
029    import org.apache.hadoop.classification.InterfaceAudience;
030    import org.apache.hadoop.classification.InterfaceStability;
031    import org.apache.hadoop.io.RawComparator;
032    
033    /**
034     * <p>
035     * An experimental {@link Serialization} for Java {@link Serializable} classes.
036     * </p>
037     * @see JavaSerializationComparator
038     */
039    @InterfaceAudience.Public
040    @InterfaceStability.Unstable
041    public class JavaSerialization implements Serialization<Serializable> {
042    
043      static class JavaSerializationDeserializer<T extends Serializable>
044        implements Deserializer<T> {
045    
046        private ObjectInputStream ois;
047    
048        public void open(InputStream in) throws IOException {
049          ois = new ObjectInputStream(in) {
050            @Override protected void readStreamHeader() {
051              // no header
052            }
053          };
054        }
055        
056        @SuppressWarnings("unchecked")
057        public T deserialize(T object) throws IOException {
058          try {
059            // ignore passed-in object
060            return (T) ois.readObject();
061          } catch (ClassNotFoundException e) {
062            throw new IOException(e.toString());
063          }
064        }
065    
066        public void close() throws IOException {
067          ois.close();
068        }
069    
070      }
071    
072      static class JavaSerializationSerializer
073        implements Serializer<Serializable> {
074    
075        private ObjectOutputStream oos;
076    
077        public void open(OutputStream out) throws IOException {
078          oos = new ObjectOutputStream(out) {
079            @Override protected void writeStreamHeader() {
080              // no header
081            }
082          };
083        }
084    
085        public void serialize(Serializable object) throws IOException {
086          oos.reset(); // clear (class) back-references
087          oos.writeObject(object);
088        }
089    
090        public void close() throws IOException {
091          oos.close();
092        }
093    
094      }
095    
096      @InterfaceAudience.Private
097      public boolean accept(Class<?> c) {
098        return Serializable.class.isAssignableFrom(c);
099      }
100    
101      @InterfaceAudience.Private
102      public Deserializer<Serializable> getDeserializer(Class<Serializable> c) {
103        return new JavaSerializationDeserializer<Serializable>();
104      }
105    
106      @InterfaceAudience.Private
107      public Serializer<Serializable> getSerializer(Class<Serializable> c) {
108        return new JavaSerializationSerializer();
109      }
110    
111    }