单例模式

 1 /**
 2 * 懒汉式单例模式
 3 * @author Administrator
 4 *
 5 */
 6 public class Singleton{
 7 private static Singleton _instance = null;
 8 
 9 //构造方法私有，保证外界无法直接实例化
10 private Singleton(){
11 
12 }
13 
14 //方法同步
15 synchronized public static Singleton getInsatance(){
16 if(_instance == null){
17 _instance = new Singleton();
18 }
19 
20 return _instance;
21 }
22 
23 }