java---Serializable(序列化)

1、什么是序列化和反序列化

Serialization（序列化）是一种将对象以一连串的字节描述的过程；反序列化deserialization是一种将这些字节重建成一个对象的过程。

2、什么情况下需要序列化 
a）当你想把的内存中的对象保存到一个文件中或者数据库中时候；
b）当你想用套接字在网络上传送对象的时候；

3、如何实现序列化

将需要序列化的类实现Serializable接口，Serializable接口中没有任何方法，可以理解为一个标记，即表明这个类可以序列化。

package ThreadIO2_1.IO.seriailizable;

import java.io.Serializable;

public class Address implements Serializable {
/**
* 静态变量是不会被序列化的。对于非静态变量，
* 一般情况下都会被序列化，
* 但如果声明成transient型则不会 transient（瞬时变量）
*/

transient int num;//瞬时变量---该变量是不会被序列化的---不会出现在对象图中的
private String name;
private int age;
private String tel;
public Address(String name, int age, String tel) {
super();
this.name = name;
this.age = age;
this.tel = tel;
}
public Address(int num, String name, int age, String tel) {
super();
this.num = num;
this.name = name;
this.age = age;
this.tel = tel;
}
@Override
public String toString() {
return "Address [num=" + num + ", 姓名=" + name + ", 年龄=" + age
+ ",电话=" + tel + "]";
}

}

package io.serializable;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;

public class SerializableDemo {

public static void main(String[] args) throws Exception {
//demo1();
demo2();
}

private static void demo2() throws FileNotFoundException, IOException,
ClassNotFoundException {
//对象序列化---输出，写
OutputStream fout = new FileOutputStream("a.txt");
ObjectOutputStream out = new ObjectOutputStream(fout);
out.writeObject( new Address(1,"aa",23,"13588888888"));
out.writeObject( new Address(2,"bb",24,"13566666666"));
out.writeObject( new Address(3,"cc",23,"13577777777"));
out.writeObject( new Address(4,"dd",25,"13599999999"));
out.close();

//反序列化----读
InputStream fin = new FileInputStream("a.txt");
ObjectInputStream in = new ObjectInputStream(fin);
System.out.println( in.readObject() );
System.out.println( in.readObject() );
System.out.println( in.readObject() );
System.out.println( in.readObject() );
}

private static void demo1() throws FileNotFoundException, IOException,
ClassNotFoundException {
//对象序列化---输出，写
OutputStream fout =
4000
new FileOutputStream("a.txt");
ObjectOutputStream out = new ObjectOutputStream(fout);
out.writeObject( new Address("aa",23,"13588888888"));
out.writeObject( new Address("bb",24,"13566666666"));
out.writeObject( new Address("cc",23,"13577777777"));
out.writeObject( new Address("dd",25,"13599999999"));
out.close();

//反序列化----读
InputStream fin = new FileInputStream("a.txt");
ObjectInputStream in = new ObjectInputStream(fin);
System.out.println( in.readObject() );
System.out.println( in.readObject() );
System.out.println( in.readObject() );
System.out.println( in.readObject() );
}

}