Hadooop序列化框架使用

第一步:实现Writable接口(TestGenericWritable.java)
 public static class Baz extends Bar {
    @Override
    public void readFields(DataInput in) throws IOException {
      super.readFields(in);
      //needs a configuration parameter
      assertEquals("Configuration is not set for the wrapped object", 
          CONF_TEST_VALUE, getConf().get(CONF_TEST_KEY)); 
    }
    @Override
    public void write(DataOutput out) throws IOException {
      super.write(out);
    }
  }
  /////////////////////////////////////////////////////////////
  Text before = new Text("test writable");
第二步：在序列化工厂中获取所有支持的序列化/反序列化JavaSerialization/WritableSerialization/AvroSerialization/AvroReflectSerialization/AvroSpecificSerialization
SerializationFactory factory = new SerializationFactory(conf);
    Serializer<K> serializer 
      = factory.getSerializer(GenericsUtil.getClass(before));
    Deserializer<K> deserializer 
      = factory.getDeserializer(GenericsUtil.getClass(before));
第三步：定义输入/输出并对数据进行序列化
 DataOutputBuffer out = new DataOutputBuffer();
    serializer.open(out);
    serializer.serialize(before);
    serializer.close();

    DataInputBuffer in = new DataInputBuffer();
    in.reset(out.getData(), out.getLength());
    deserializer.open(in);
    K after = deserializer.deserialize(null);
    deserializer.close();