java 序列化与反序列化

1.序列化：

将java对象转化为字节序列

2.反序列化：

将字节序列恢复成java对象

3.序列化是干什么的：

1.保存在内存中的对象的状态

2.方便传输，实现对象的字节序列传输，如图像，视频等

4.实现

java提供两种方式一种是实现Serializable接口，另一种是实现Exteranlizable接口，使用Serializable时可利用transient关键子修饰不需要被反序列化的属性，使用Exteranlizable接口时需要重写writeExternal和readExternal方法

 

user类实现Serializable接口，实际为空接口，作为可反序列化标识

 

import java.io.Serializable;

public class User implements Serializable {

    private String Name;

    private int age;

    public String getName() {

        return Name;

    }

    public void setName(String name) {

        Name = name;

    }

 

    public int getAge() {

        return age;

    }

    public void setAge(int age) {

        this.age = age;

    }

    public User(String name, int age) {

        Name = name;

        this.age = age;

    }

}

Exteranlizable类继承了Serializable需要实现writeExternal和readExternal方法，注意使用此方法时，若类没有默认构造函数会报错

import java.io.*;

public class User implements Externalizable {

    private String Name;

    private int age;

 

    public String getName() {

        return Name;

    }

    public void setName(String name) {

        Name = name;

    }

    public int getAge() {

        return age;

    }

    public void setAge(int age) {

        this.age = age;

    }

 

    public User(){

 

    }

    public User(String name, int age) {

        Name = name;

        this.age = age;

    }

    @Override

    public void writeExternal(ObjectOutput out) throws IOException {

        out.writeObject(Name);

        out.writeObject(age);

    }

    @Override

    public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {

         Name = (String) in.readObject();

         age  = (int) in.readObject();

    }

}

objectOutputStream 对象输出流 objectInputStream 对象输入流

FileOutputStream 文件输出流 FileInputStream 文件输入流

利用两者将对象的序列化数据写入文件，再从文件中读取序列化数据利用readObject恢复成对象

test类代码如下：

import java.io.*;

public class test {

    public static void main(String[] args) throws IOException,ClassNotFoundException{

        Serialize();

        DeSerializ();

    }

    private static void Serialize() throws IOException {

        FileOutputStream fos = new FileOutputStream("D://java test//Serial//1.txt");

        ObjectOutputStream oos = new ObjectOutputStream(fos);

        User user1=new User("xxx",21);

        oos.writeObject(user1);

        System.out.print(oos);

        oos.flush();

        oos.close();

    }

    private static void DeSerializ() throws IOException, ClassNotFoundException {

        FileInputStream fis=new FileInputStream("D://java test//Serial//1.txt");

        ObjectInputStream ois=new ObjectInputStream(fis);

        System.out.print(ois+"\n");

        User user2=(User) ois.readObject();

        System.out.print(user2.getName()+user2.getAge());

    }

}

运行Serialize()在1.txt中保存序列化数据

 

运行DeSerializ()将序列化数据反序列化为对象