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 [设计模式]『蚂蚁学模式』之实例化单例模式（一）
软件技术
lhwork 发表于 2007/1/10 9:31:57 |
| 饿汉式单例com.cleversoft.designpatterns.singleton1.Singleton.java:
500)this.width=500'>package com.cleversoft.designpatterns.singleton1;500)this.width=500'>500)this.width=500'>500)this.width=500'>/** *//**500)this.width=500'> * Hungry Singleton500)this.width=500'> * 500)this.width=500'> */500)this.width=500'>500)this.width=500'>public class Singleton 500)this.width=500'>{500)this.width=500'>500)this.width=500'> private static Singleton singleton = new Singleton();500)this.width=500'>500)this.width=500'>500)this.width=500'> private Singleton() 500)this.width=500'>{500)this.width=500'> }500)this.width=500'>500)this.width=500'>500)this.width=500'> public static Singleton getInstance() 500)this.width=500'>{500)this.width=500'> return singleton;500)this.width=500'> }500)this.width=500'>500)this.width=500'>500)this.width=500'> public String demoMethod() 500)this.width=500'>{500)this.width=500'> return "This is a hungry singleton demo!";500)this.width=500'> }500)this.width=500'>}com.cleversoft.designpatterns.singleton1.Main.java:
500)this.width=500'>package com.cleversoft.designpatterns.singleton1;500)this.width=500'>500)this.width=500'>500)this.width=500'>public class Main 500)this.width=500'>{500)this.width=500'>500)this.width=500'>500)this.width=500'> /** *//**500)this.width=500'> * @param args500)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'> // TODO Auto-generated method stub500)this.width=500'> System.out.println(Singleton.getInstance().demoMethod());500)this.width=500'> }500)this.width=500'>500)this.width=500'>}懒汉式单例com.cleversoft.designpatterns.singleton2.LazySingleton.java:
500)this.width=500'>package com.cleversoft.designpatterns.singleton2;500)this.width=500'>500)this.width=500'>500)this.width=500'>/** *//**500)this.width=500'> * Lazy Singleton500)this.width=500'> * 500)this.width=500'> */500)this.width=500'>500)this.width=500'>public class LazySingleton 500)this.width=500'>{500)this.width=500'> static boolean instance_flag = false;500)this.width=500'>500)this.width=500'>500)this.width=500'> private LazySingleton() 500)this.width=500'>{500)this.width=500'> }500)this.width=500'>500)this.width=500'>500)this.width=500'> synchronized public static LazySingleton getInstance() 500)this.width=500'>{500)this.width=500'>500)this.width=500'> if (!instance_flag) 500)this.width=500'>{500)this.width=500'> instance_flag = true;500)this.width=500'> return new LazySingleton();500)this.width=500'> } else500)this.width=500'> return null;500)this.width=500'> }500)this.width=500'>500)this.width=500'>}com.cleversoft.designpatterns.singleton2.Main.java:
500)this.width=500'>package com.cleversoft.designpatterns.singleton2;500)this.width=500'>500)this.width=500'>500)this.width=500'>public class Main 500)this.width=500'>{500)this.width=500'>500)this.width=500'>500)this.width=500'> /** *//**500)this.width=500'> * @param args500)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'> // TODO Auto-generated method stub500)this.width=500'> LazySingleton ls1, ls2;500)this.width=500'> System.out.println("Start to get first Instance500)this.width=500'>");500)this.width=500'> ls1 = LazySingleton.getInstance();500)this.width=500'>500)this.width=500'> if (ls1 != null)500)this.width=500'>{500)this.width=500'> System.out.println("This is the first Instance!\n");500)this.width=500'> }500)this.width=500'> 500)this.width=500'> System.out.println("Start to get second Instance500)this.width=500'>");500)this.width=500'> ls2 = LazySingleton.getInstance();500)this.width=500'>500)this.width=500'> if (ls2 != null)500)this.width=500'>{500)this.width=500'> System.out.println("This is the second Instance!");500)this.width=500'> }500)this.width=500'>500)this.width=500'> else500)this.width=500'>{ 500)this.width=500'> System.out.println("You can just get 1 Instance!");500)this.width=500'> }500)this.width=500'> 500)this.width=500'> }500)this.width=500'>500)this.width=500'>}引用： >强烈建议大家不要再花时间在实现双重检查成例上是这样，不必在这上面钻牛角尖，而且单例模式在实际应用中已经逐步被Ioc容器替代，实用价值不高。（banq）(http://www.jdon.com/jive/thread.jsp?forum=91&thread=23890)参考资料：1. 《Java与模式》2. http://www.java2s.com |
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