【设计模式学习笔记】单例模式

- 日理万妓 2022-03-26 08:19 166阅读 0赞

> 单例模式，只能获取一个实例。

## 文章目录 ##

[1.1 单例模式-懒汉模式][1.1 _-]

[1.2 单例模式-饿汉模式][1.2 _-]

[1.3测试][1.3]

[1.4 结果][1.4]

[参考][Link 1]

##  1.1 单例模式-懒汉模式 ##

package singleton;
    
    /************************************************
     *@ClassName : single
     *@Description : 第一种单例模式，懒汉模式
     *@Author : NikolaZhang
     *@Date : 【2018/11/29 21:47】
     *@Version : 1.0.0
     *************************************************/
    
    public class MainCompany {
        private static MainCompany mainCompany = null;
        public static MainCompany getInstance(){
            if(mainCompany == null){
                mainCompany = new MainCompany();
            }
            return mainCompany;
        }
    
        public static void getInfo(){
            System.out.println("总部只能有一个！"+mainCompany);
        }
    }

##  1.2 单例模式-饿汉模式 ##

package singleton;
    
    /************************************************
     *@ClassName : MainCompany2
     *@Description : 第二种单例模式，饿汉模式
     *@Author : NikolaZhang
     *@Date : 【2018/11/29 21:59】
     *@Version : 1.0.0
     *************************************************/
    
    public class MainCompany2 {
        private final static MainCompany2 mainCompany2 = new MainCompany2();
    
        public static MainCompany2 getInstance(){
            return mainCompany2;
        }
    
        public void getInfo(){
            System.out.println("饿汉模式"+mainCompany2);
        }
    }

## 1.3测试 ##

package singleton;
    
    /************************************************
     *@ClassName : Test
     *@Description : TODO
     *@Author : NikolaZhang
     *@Date : 【2018/11/29 21:50】
     *@Version : 1.0.0
     *************************************************/
    
    public class Test {
        public static void main(String[] args) {
            MainCompany mainCom1 = MainCompany.getInstance();
            mainCom1.getInfo();
            MainCompany mainCom2 = MainCompany.getInstance();
            mainCom2.getInfo();
            System.out.println("====================================");
    
            MainCompany2 com1 = MainCompany2.getInstance();
            com1.getInfo();
            MainCompany2 com2 = MainCompany2.getInstance();
            com2.getInfo();
    
            System.out.println("如果每组上下两个的地址相同则单例成功，不过推荐下面的方式");
        }
    }

##  1.4 结果 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhaWR1XzMwMzI1MDA5_size_16_color_FFFFFF_t_70][]

## 参考 ##

【菜鸟教程】：[http://www.runoob.com/design-pattern/singleton-pattern.html][http_www.runoob.com_design-pattern_singleton-pattern.html]

本文原文地址：[https://blog.csdn.net/baidu\_30325009/article/details/85028538][https_blog.csdn.net_baidu_30325009_article_details_85028538]

[1.1 _-]: https://blog.csdn.net/baidu_30325009/article/details/85028538#11__5
[1.2 _-]: https://blog.csdn.net/baidu_30325009/article/details/85028538#12__33
[1.3]: https://blog.csdn.net/baidu_30325009/article/details/85028538#13_59
[1.4]: https://blog.csdn.net/baidu_30325009/article/details/85028538#14__90
[Link 1]: https://blog.csdn.net/baidu_30325009/article/details/85028538#_93
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhaWR1XzMwMzI1MDA5_size_16_color_FFFFFF_t_70]: /images/20220326/1d60ff1051a9443888e3ccdb2cf90c2c.png
[http_www.runoob.com_design-pattern_singleton-pattern.html]: http://www.runoob.com/design-pattern/singleton-pattern.html
[https_blog.csdn.net_baidu_30325009_article_details_85028538]: https://blog.csdn.net/baidu_30325009/article/details/85028538