单例模式（懒汉式）防止反射漏洞

public class SingLazy {
    //类的初始化 不初始化这个对象（延迟加载，用到再创建）
    private  static SingLazy instane;
    //私有化构造器
    private SingLazy(){
        
     //多次调用，抛出异常，防止反射
        if(instane!=null){
            throw new RuntimeException();
        }

    }

    //方法同步，销量低
    public static  synchronized SingLazy gets(){
        if(instane==null){
            instane=new SingLazy();
        }

        return instane;
    }
}