Java Serialization類代碼示例

import org.apache.hadoop.io.serializer.Serialization; //導入依賴的package包/類
private <E> E makeCopyForPassByValue(Serialization<E> serialization,
                                      E obj) throws IOException {
  Serializer<E> ser =
    serialization.getSerializer(GenericsUtil.getClass(obj));
  Deserializer<E> deser =
    serialization.getDeserializer(GenericsUtil.getClass(obj));

  DataOutputBuffer dof = threadLocalDataOutputBuffer.get();

  dof.reset();
  ser.open(dof);
  ser.serialize(obj);
  ser.close();
  obj = ReflectionUtils.newInstance(GenericsUtil.getClass(obj),
                                    getChainJobConf());
  ByteArrayInputStream bais =
    new ByteArrayInputStream(dof.getData(), 0, dof.getLength());
  deser.open(bais);
  deser.deserialize(obj);
  deser.close();
  return obj;
}
 

import org.apache.hadoop.io.serializer.Serialization; //導入依賴的package包/類
/**
 * Gets serializer for specified class.
 *
 * @param cls Class.
 * @param jobConf Job configuration.
 * @return Appropriate serializer.
 */
@SuppressWarnings("unchecked")
private HadoopSerialization getSerialization(Class<?> cls, Configuration jobConf) throws IgniteCheckedException {
    A.notNull(cls, "cls");

    SerializationFactory factory = new SerializationFactory(jobConf);

    Serialization<?> serialization = factory.getSerialization(cls);

    if (serialization == null)
        throw new IgniteCheckedException("Failed to find serialization for: " + cls.getName());

    if (serialization.getClass() == WritableSerialization.class)
        return new HadoopWritableSerialization((Class<? extends Writable>)cls);

    return new HadoopSerializationWrapper(serialization, cls);
}
 

import org.apache.hadoop.io.serializer.Serialization; //導入依賴的package包/類
/**
 * Returns the OutputCollector to be used by a Mapper instance in the chain.
 *
 * @param mapperIndex index of the Mapper instance to get the OutputCollector.
 * @param output      the original OutputCollector of the task.
 * @param reporter    the reporter of the task.
 * @return the OutputCollector to be used in the chain.
 */
@SuppressWarnings({"unchecked"})
public OutputCollector getMapperCollector(int mapperIndex,
                                          OutputCollector output,
                                          Reporter reporter) {
  Serialization keySerialization = mappersKeySerialization.get(mapperIndex);
  Serialization valueSerialization =
    mappersValueSerialization.get(mapperIndex);
  return new ChainOutputCollector(mapperIndex, keySerialization,
                                  valueSerialization, output, reporter);
}
 

import org.apache.hadoop.io.serializer.Serialization; //導入依賴的package包/類
public ChainOutputCollector(int index, Serialization<K> keySerialization,
                            Serialization<V> valueSerialization,
                            OutputCollector output, Reporter reporter) {
  this.nextMapperIndex = index + 1;
  this.keySerialization = keySerialization;
  this.valueSerialization = valueSerialization;
  this.output = output;
  this.reporter = reporter;
}
 

import org.apache.hadoop.io.serializer.Serialization; //導入依賴的package包/類
@SuppressWarnings({"unchecked"})
public void collect(K key, V value) throws IOException {
  if (nextMapperIndex < mappers.size()) {
    // there is a next mapper in chain

    // only need to ser/deser if there is next mapper in the chain
    if (keySerialization != null) {
      key = makeCopyForPassByValue(keySerialization, key);
      value = makeCopyForPassByValue(valueSerialization, value);
    }

    // gets ser/deser and mapper of next in chain
    Serialization nextKeySerialization =
      mappersKeySerialization.get(nextMapperIndex);
    Serialization nextValueSerialization =
      mappersValueSerialization.get(nextMapperIndex);
    Mapper nextMapper = mappers.get(nextMapperIndex);

    // invokes next mapper in chain
    nextMapper.map(key, value,
                   new ChainOutputCollector(nextMapperIndex,
                                            nextKeySerialization,
                                            nextValueSerialization,
                                            output, reporter),
                   reporter);
  } else {
    // end of chain, user real output collector
    output.collect(key, value);
  }
}