单例模式

饥汉模式：public class Singleton {private static Singleton singleton = new Singleton();   //JVM加载Singleton时创建private Singleton(){}      //私有化构造方法public static Singleton getSingleton(){return singleton;} }饱汉模式：public class Singleton {private static Singleton singleton;private Singleton(){}public static synchronized Singleton getSingleton(){if(singleton == null){singleton = new Singleton();}return singleton;}}