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 [设计模式]『蚂蚁学模式』之实例化单例模式（二）
软件技术
lhwork 发表于 2007/1/10 9:31:03 |
| 前面说了单例模式，这次说说单例模式的推广——多例模式。有上限多例模式com.cleversoft.designpatterns.multiton.Die.java:
500)this.width=500'>package com.cleversoft.designpatterns.multiton;500)this.width=500'>500)this.width=500'>import java.util.Random;500)this.width=500'>import java.util.Date;500)this.width=500'>500)this.width=500'>500)this.width=500'>public class Die 500)this.width=500'>{500)this.width=500'> private static Die die1 = new Die();500)this.width=500'>500)this.width=500'> private static Die die2 = new Die();500)this.width=500'>500)this.width=500'>500)this.width=500'> private Die() 500)this.width=500'>{500)this.width=500'> }500)this.width=500'>500)this.width=500'>500)this.width=500'> public static Die getInstance(int whichOne) 500)this.width=500'>{500)this.width=500'>500)this.width=500'> if (whichOne == 1) 500)this.width=500'>{500)this.width=500'> return die1;500)this.width=500'>500)this.width=500'> } else 500)this.width=500'>{500)this.width=500'> return die2;500)this.width=500'> }500)this.width=500'> }500)this.width=500'>500)this.width=500'>500)this.width=500'> public synchronized int dice() 500)this.width=500'>{500)this.width=500'> Date d = new Date();500)this.width=500'>500)this.width=500'> Random r = new Random(d.getTime());500)this.width=500'> int value = r.nextInt();500)this.width=500'> value = Math.abs(value);500)this.width=500'>500)this.width=500'> value = value % 6;500)this.width=500'> value += 1;500)this.width=500'> System.out.println(value);500)this.width=500'> return value;500)this.width=500'> }500)this.width=500'>500)this.width=500'>}com.cleversoft.designpatterns.multiton.Main.java:
500)this.width=500'>package com.cleversoft.designpatterns.multiton;500)this.width=500'>500)this.width=500'>500)this.width=500'>public class Main 500)this.width=500'>{500)this.width=500'> private static Die die1;500)this.width=500'>500)this.width=500'> private static Die die2;500)this.width=500'>500)this.width=500'>500)this.width=500'> public static void main(String[] args) 500)this.width=500'>{500)this.width=500'> die1 = Die.getInstance(1);500)this.width=500'> die2 = Die.getInstance(2);500)this.width=500'>500)this.width=500'> die1.dice();500)this.width=500'> die2.dice();500)this.width=500'> }500)this.width=500'>}无上限多例模式比较合适的例子就是在应用程序中的“多语言支持”和序列键生成器。参考资料：《Java与模式》 |
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