设计模式-单例模式

package test;

/**
 * 饿汉式单列模式
 * @author lenovo
 *
 */
public class Singleton1 {
    private static Singleton1 Singleton1=new Singleton1();
    private Singleton1(){
        
    }
    
    public static Singleton1 getSingleton1(){
        return Singleton1;
    }
    
}

package test;

/**
 * 此单例模式可以应用于多线程
 * @author lenovo
 *
 */
public class Singleton2 {
    private static Singleton2 singleton2=null;
    private Singleton2(){}
    public static Singleton2 getSingleton2(){
        if(singleton2==null){
            synchronized (Singleton2.class) { 
                if(singleton2==null){
                    singleton2=new Singleton2();
                }
            }
        }
        return singleton2;
    }
}