package cn.test.serializable;
/**
 * 序列化对象实现Serializable接口
 * @author Young
 * created on 2017-5-25
 */
import java.io.Serializable;
public class Student implements Serializable {
  private String id;
  private String name;
  public Student (String id,String name){
    this.id=id;
    this.name=name;
  }
  public String getId() {
    return id;
  }
  public void setId(String id) {
    this.id = id;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
}

package cn.test.serializable;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
/**
 * 序列化
 * @author Young
 * created on 2017-5-25
 */
public class TestSerializable {
  public static void main(String[] args) {
    // TODO Auto-generated method stub
    Student stu=new Student("201441413110","yang");
    try {
      FileOutputStream out=new FileOutputStream("d:\student");//创建OutputStream对象
      ObjectOutputStream ob=new ObjectOutputStream(out);//封装在一个ObjectOutputStream对象内
      ob.writeObject(stu);//调用writeObject()方法将对象序列化并发送给OutputStream,保存在d:\student中
      ob.close();
      out.close();
    } catch (FileNotFoundException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }
}

package cn.test.serializable;
/**
 * 反序列化
 * @author Young
 * created on 2017-5-25
 */
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.ObjectInputStream;
public class TestDeserializable {
  public static void main(String[] args) {
    // TODO Auto-generated method stub
    FileInputStream in;
    Student stu;
    try {
      in = new FileInputStream("d:\student");
      ObjectInputStream ob=new ObjectInputStream(in);//InputStream封装在ObjectInputStream内
      stu=(Student) ob.readObject();//调用readObject()，得到的结果是一个Object对象，需要进行转型得到最后所需的对象.
      ob.close();
      in.close();
      System.out.println(stu.getId());
      System.out.println(stu.getName());
    } catch (FileNotFoundException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (ClassNotFoundException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }
}

package Hadoop.writable;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Writable;
/**
 * hadoop 序列化与反序列化
 * @author Young
 * created by 2017-6-9
 */
public class Serialize {
  public static byte[] serialize(Writable writable) throws IOException{
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    DataOutputStream dataout = new DataOutputStream(out);
    try {
      writable.write(dataout);
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }finally{
      dataout.close();
    }
    return out.toByteArray();
  }
  public static byte[] deserialize(Writable writable ,byte[] bytes) throws IOException{
    ByteArrayInputStream in = new ByteArrayInputStream(bytes);
    DataInputStream datain = new DataInputStream(in);
    try {
      writable.readFields(datain);
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    finally{
      datain.close();
    }
    return bytes;
  }
  public static void main(String[] args) throws IOException {
    // TODO Auto-generated method stub
    IntWritable intwritable = new IntWritable(20);
    IntWritable newwriatble =new IntWritable();
    byte[] bytes=Serialize.serialize(intwritable);
    deserialize(newwriatble,bytes);
    System.out.println(newwriatble.get());
  }
}

package org.apache.hadoop.io;
import org.apache.hadoop.classification.InterfaceAudience.Public;
import org.apache.hadoop.classification.InterfaceStability.Stable;
import org.apache.hadoop.io.Writable;
@Public
@Stable
public interface WritableComparable<T> extends Writable, Comparable<T> {
}

package org.apache.hadoop.io;
import java.util.Comparator;
import org.apache.hadoop.classification.InterfaceAudience.Public;
import org.apache.hadoop.classification.InterfaceStability.Stable;
@Public
@Stable
public interface RawComparator<T> extends Comparator<T> {
  int compare(byte[] arg0, int arg1, int arg2, byte[] arg3, int arg4, int arg5);
}

RawComparator<IntWritable>comparator=WritableComparator.get(IntWritable.class);

package cn.serialization;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.RawComparator;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableComparator;
public class TestWritable {
  //序列化
  public static byte[] serialize(Writable writable) throws IOException{
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    DataOutputStream dataOut= new DataOutputStream(out);
    writable.write(dataOut);
    dataOut.close();
    return out.toByteArray();
  }
  //反序列化
  public static byte[] deserialize(Writable writable, byte[] bytes) throws IOException{
    ByteArrayInputStream in = new ByteArrayInputStream(bytes);
    DataInputStream dataIn = new DataInputStream(in);
    writable.readFields(dataIn);
    dataIn.close();
    return bytes;
  }
  public static void main(String[] args) throws IOException {
    @SuppressWarnings("unchecked")
    RawComparator <IntWritable> comparator = WritableComparator.get(IntWritable.class);
    IntWritable w1 = new IntWritable(163);
    IntWritable w2 = new IntWritable(67);
    byte[] b1 = serialize(w1);
    byte[] b2 = serialize(w2);
    System.out.println(b1);
    System.out.println(b2);
    System.out.println(comparator.compare(w1, w2));//WritableComparator的 compare()，w1>w2 -> 1;w1<w2 -> -1 ; w1=w2 -> 0
  System.out.println(comparator.compare(b1,0,b1.length,b2,0,b2.length));
  }
}

public class WritableSerialization extends Configured implements Serialization<Writable> {...}

public interface Serializer<T> {
  void open(OutputStream arg0) throws IOException;
  void serialize(T arg0) throws IOException;
  void close() throws IOException;
}

public interface Deserializer<T> {
  void open(InputStream arg0) throws IOException;
  T deserialize(T arg0) throws IOException;
  void close() throws IOException;
}

public interface Serialization<T> {
  boolean accept(Class<?> arg0);
  Serializer<T> getSerializer(Class<T> arg0);
  Deserializer<T> getDeserializer(Class<T> arg0);
}