设计模式__单例模式

单例模式是java的23中设计模式中最为简单的一种，他分为两种情况，恶汉模式跟懒汉模式，很简单的看代码便知

恶汉模式案例：

/**
 * 恶汉模式
 * 即是当调用的时候创建
 * Created by Administrator on 2017/4/2.
 */
public class Singleton {
    private static Singleton singleton;
    private Singleton(){}
    public static Singleton getInstance(){
        if(singleton==null){
            singleton = new Singleton();
            return singleton;
        }else{
            return singleton;
        }
    }
}
-----------------------------------------------------------------------
//测试用例
public class Test {
    public static void main(String[] args) {
        Singleton singleton1 = Singleton.getInstance();
        Singleton singleton2 = Singleton.getInstance();
        System.out.println(singleton1==singleton2);
    }
}

懒汉模式案例

/**
 * 懒汉模式
 * 即是当调用的时候创建
 * Created by Administrator on 2017/4/2.
 */
public class Singleton {
    private static final Singleton singleton = new Singleton();
    private Singleton(){}
    public static Singleton getInstance(){
            return singleton;
    }
}
------------------------------------------------------------------------------------
//测试用例
public class Test {
    public static void main(String[] args) {
        Singleton singleton1 = Singleton.getInstance();
        Singleton singleton2 = Singleton.getInstance();
        System.out.println(singleton1==singleton2);
    }
}