java中的transient-优快云博客

本文通过一个Java示例程序介绍了如何使用transient关键字来排除对象中的敏感字段，在序列化过程中避免这些字段被保存。示例展示了含有transient关键字的密码字段在序列化前后的情况。

transient:用于声明序列化的时候不被存储

示例

import java.io.*; 
import java.util.*; 

public class Logon implements Serializable { 
	private Date date = new Date(); 
	private String username; 
	private transient String password; 
	Logon(String name, String pwd) { 
		username = name; 
		password = pwd; 
	} 
	public String toString() { 
		String pwd = 
			(password == null) ? "(n/a)" : password; 
		return "logon info: \n " + 
		"username: " + username + 
		"\n date: " + date.toString() + 
		"\n password: " + pwd; 
	} 
	public static void main(String[] args) { 
		Logon a = new Logon("Hulk", "myLittlePony"); 
		System.out.println( "logon a = " + a); 
		try { 
			ObjectOutputStream o = 
				new ObjectOutputStream( 
						new FileOutputStream("Logon.out")); 
			o.writeObject(a); 
			o.close(); 
			// Delay: 
			int seconds = 5; 
			long t = System.currentTimeMillis() 
			+ seconds * 1000; 
			while(System.currentTimeMillis() < t) 
				; 
			// Now get them back: 
			ObjectInputStream in = 
				new ObjectInputStream( 
						new FileInputStream("Logon.out")); 
			System.out.println( 
					"Recovering object at " + new Date()); 
			a = (Logon)in.readObject(); 
			System.out.println( "logon a = " + a); 
		} catch(Exception e) { 
			e.printStackTrace(); 
		} 
	} 
} ///:~

输出：

logon a = logon info:
username: Hulk
date: Sat Apr 09 20:52:21 CST 2011
password: myLittlePony
Recovering object at Sat Apr 09 20:52:26 CST 2011
logon a = logon info:
username: Hulk
date: Sat Apr 09 20:52:21 CST 2011
password: (n/a)