Java单例模式

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;
	}
}

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;
	}
	
}

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;
	}
	
}

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