单例模式

两种最好的单例模式  mark一下

1 双重加锁模式

public class Singleton {

private Singleton() {};

private volatile static Singleton single=null;

public static Singleton getInstance() {

if (single == null) {

synchronized (Singleton.class) {

if (single== null) {single = new Singleton();}

}

}

return single;

}

}

2 静态内部类方式

public class Singleton {

private static class Holder {

private static final Singleton INSTANCE = new Singleton();}

private Singleton (){}

public static final Singleton getInstance() {

return Holder.INSTANCE;}

}