Transient关键字的作用

在对象序列化的时候，有些变量不需要序列化，比如密码等，可以使用transient关键字来解决这个问题，transient修饰的变量不会被序列化。

例子：

import java.io.*;
import java.util.Date;
 
 4 
/**
 * Created by leiqiang on 2014/7/25.
 */
public class TransientTest implements Serializable{
    private Date date = new Date();
    private String username;
    private transient String password;

    public TransientTest(String username,String password){
        this.username=username;
        this.password=password;
    }

    @Override
    public String toString() {
        return new Date()+" username "+username+" : password "+password;
    }

    public static void main(String[] args) throws Exception{
        TransientTest transientTest = new TransientTest("lei","1234");
        System.out.println(transientTest);
        FileOutputStream fileOutputStream = new FileOutputStream("d:/Cache/TransientTest.txt");
        ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
        objectOutputStream.writeObject(transientTest);
        objectOutputStream.close();
        Thread.sleep(2000);
        FileInputStream fileInputStream = new FileInputStream("d:/Cache/TransientTest.txt");
        ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
        transientTest = (TransientTest)objectInputStream.readObject();
        System.out.println(transientTest);
    }
}

运行结果：

Fri Jul 25 13:56:13 CST 2014 username lei : password 1234
Fri Jul 25 13:56:15 CST 2014 username lei : password null