Java序列化的几种方式以及序列化的作用

package com.shop.domain;
 
import java.util.Date;
 
 
public class Article implements java.io.Serializable {
    private static final long serialVersionUID = 1L;
    private Integer id;  
    private String title;  //文章标题
    private String content;  // 文章内容
    private String faceIcon;//表情图标
    private Date postTime; //文章发表的时间
    private String ipAddr;  //用户的ip
     
    private User author;  //回复的用户
     
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getContent() {
        return content;
    }
    public void setContent(String content) {
        this.content = content;
    }
    public String getFaceIcon() {
        return faceIcon;
    }
    public void setFaceIcon(String faceIcon) {
        this.faceIcon = faceIcon;
    }
    public Date getPostTime() {
        return postTime;
    }
    public void setPostTime(Date postTime) {
        this.postTime = postTime;
    }
    public User getAuthor() {
        return author;
    }
    public void setAuthor(User author) {
        this.author = author;
    }
    public String getIpAddr() {
        return ipAddr;
    }
    public void setIpAddr(String ipAddr) {
        this.ipAddr = ipAddr;
    }
     
     
}

* @see java.io.ObjectInput
 * @see java.io.Serializable
 * @since   JDK1.1
 */
public interface Externalizable extends java.io.Serializable {
    /**
     * The object implements the writeExternal method to save its contents
     * by calling the methods of DataOutput for its primitive values or

package com.xiaohao.test;
 
import java.io.Externalizable;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
import java.text.SimpleDateFormat;
import java.util.Date;
 
 
/**
 * 测试实体类
 * @author 小浩
 * @创建日期 2015-3-12
 */
class Person implements Externalizable{
        private static final long serialVersionUID = 1L;<br>    String userName;
    String password;
    String age;
     
   
    public Person(String userName, String password, String age) {
        super();
        this.userName = userName;
        this.password = password;
        this.age = age;
    }
     
     
    public Person() {
        super();
    }
 
 
    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
     
    /**
     * 序列化操作的扩展类
     */
    @Override
    public void writeExternal(ObjectOutput out) throws IOException {
        //增加一个新的对象
        Date date=new Date();
        out.writeObject(userName);
        out.writeObject(password);
        out.writeObject(date);
    }
     
    /**
     * 反序列化的扩展类
     */
    @Override
    public void readExternal(ObjectInput in) throws IOException,
            ClassNotFoundException {
        //注意这里的接受顺序是有限制的哦，否则的话会出错的
        // 例如上面先write的是A对象的话，那么下面先接受的也一定是A对象...
        userName=(String) in.readObject();
        password=(String) in.readObject();
        SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
        Date date=(Date)in.readObject();        
        System.out.println("反序列化后的日期为:"+sdf.format(date));
         
    }
    @Override
    public String toString() {
        //注意这里的年龄是不会被序列化的，所以在反序列化的时候是读取不到数据的
        return "用户名:"+userName+"密 码:"+password+"年龄:"+age;
    }
}
 
 
/**
 * 序列化和反序列化的相关操作类
 * @author 小浩
 * @创建日期 2015-3-12
 */
class Operate{
    /**
     * 序列化方法
     * @throws IOException 
     * @throws FileNotFoundException 
     */
    public void serializable(Person person) throws FileNotFoundException, IOException{
        ObjectOutputStream outputStream=new ObjectOutputStream(new FileOutputStream("a.txt"));
        outputStream.writeObject(person);       
    }
     
    /**
     * 反序列化的方法
     * @throws IOException 
     * @throws FileNotFoundException 
     * @throws ClassNotFoundException 
     */
    public Person deSerializable() throws FileNotFoundException, IOException, ClassNotFoundException{
        ObjectInputStream ois=new ObjectInputStream(new FileInputStream("a.txt"));
        return (Person) ois.readObject();
    }
     
 
     
}
/**
 * 测试实体主类
 * @author 小浩
 * @创建日期 2015-3-12
 */
public class Test{
    public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException {
       Operate operate=new Operate();
       Person person=new Person("小浩","123456","20");
       System.out.println("为序列化之前的相关数据如下:\n"+person.toString());
       operate.serializable(person);
       Person newPerson=operate.deSerializable();
       System.out.println("-------------------------------------------------------");
       System.out.println("序列化之后的相关数据如下:\n"+newPerson.toString());
    }
     
     
}

import java.io.*;
 
class Student1 implements Serializable {
    private static final long serialVersionUID = 1L;
    private String name;
    private transient String password;
    private static int count = 0;
 
    public Student1(String name, String password) {
        System.out.println("调用Student的带参的构造方法");
        this.name = name;
        this.password = password;
        count++;
    }
 
    public String toString() {
        return "人数: " + count + " 姓名: " + name + " 密码: " + password;
    }
}
 
public class ObjectSerTest1 {
    public static void main(String args[]) {
        try {
            FileOutputStream fos = new FileOutputStream("test.obj");
            ObjectOutputStream oos = new ObjectOutputStream(fos);
            Student1 s1 = new Student1("张三", "12345");
            Student1 s2 = new Student1("王五", "54321");
            oos.writeObject(s1);
            oos.writeObject(s2);
            oos.close();
            FileInputStream fis = new FileInputStream("test.obj");
            ObjectInputStream ois = new ObjectInputStream(fis);
            Student1 s3 = (Student1) ois.readObject();
            Student1 s4 = (Student1) ois.readObject();
            System.out.println(s3);
            System.out.println(s4);
            ois.close();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e1) {
            e1.printStackTrace();
        }
    }
}