java">package com.qcby;
//饿汉式，先new出来对象
public class Hungry {private Hungry() {};private final static Hungry hungry = new Hungry();public Hungry getinstance() {return hungry;}
}

java">package com.qcby;
//懒汉，有需要才创建
public class SuoLazy {private static volatile SuoLazy lazy ;private SuoLazy() {};public SuoLazy getinstance() {if(lazy == null) {synchronized(SuoLazy.class) {if(lazy == null) {lazy = new SuoLazy();return lazy;}}		}return null;}}

java">package com.qcby;
//懒汉，有需要才创建
public class Lazy {private static Lazy lazy ;private Lazy() {};public Lazy getinstance() {if(lazy == null) {lazy = new Lazy();}return lazy;}}

java">package com.qcby;public enum Instance {Instance;public Instance getinstance() {return Instance;}}

只要不是enum类，理论都可以被反射暴力攻击