入住博客园，先秀段代码：
1 public class Singleton { 2 3 private static Singleton instance ; 4 5 6 private Singleton() { 7 } 8 9 10 public synchronized Singleton getInstance(){ 11 if(null==instance){ 12 instance = new Singleton(); 13 } 14 return instance; 15 } 16 }
原文：http://www.cnblogs.com/xinys/p/3781936.html