西游记之设计模式原则——单一职责原则

Posted 2020-10-18 霜天晓角Megan

单一职责原则

——专心致志只做一件事

 1 package danyizhize;
 2 
 3 class SunWuKong {
 4     public void XiangMo(String name) {
 5         System.out.println(name + "降魔！");
 6     }
 7 
 8     public void XingLi(String name) {
 9         System.out.println(name + "拿行李！");
10     }
11 
12     public void QianMa(String name) {
13         System.out.println(name + "牵白龙马!");
14     }
15 
16     public void QiMa(String name) {
17         System.out.println(name + "骑马!");
18     }
19 }
20 
21 public class DanYiZhiZe {
22 
23     public static void main(String[] args) {
24         // TODO Auto-generated method stub
25         SunWuKong sunWuKong = new SunWuKong();
26         sunWuKong.XiangMo("孙悟空");
27         sunWuKong.QianMa("孙悟空");
28         sunWuKong.XingLi("孙悟空");
29         sunWuKong.QiMa("孙悟空");
30     }    
31 }

View Code

运行结果：

孙悟空降魔！
孙悟空牵白龙马!
孙悟空拿行李！
孙悟空骑马!

孙悟空的任务太多，忙不过来！！！

 

 1 package danyizhize;
 2 
 3 class SunWuKong {
 4     public void XiangMo(String name) {
 5         System.out.println(name + "降魔！");
 6     }
 7 }
 8 
 9 class ZhuBaJie {
10     public void QianMa(String name) {
11         System.out.println(name + "牵白龙马!");
12     }
13 }
14 
15 class ShaHeShang {
16     public void XingLi(String name) {
17         System.out.println(name + "拿行李！");
18     }
19 }
20 
21 class TangSeng {
22     public void QiMa(String name) {
23         System.out.println(name + "骑马!");
24     }
25 }
26 
27 public class DanYiZhiZe {
28 
29     public static void main(String[] args) {
30         // TODO Auto-generated method stub
31         SunWuKong sunWuKong = new SunWuKong();
32         ZhuBaJie zhuBaJie = new ZhuBaJie();
33         ShaHeShang shaHeShang = new ShaHeShang();
34         TangSeng tangSeng = new TangSeng();
35 
36         sunWuKong.XiangMo("孙悟空");
37         zhuBaJie.QianMa("猪八戒");
38         shaHeShang.XingLi("沙和尚");
39         tangSeng.QiMa("唐僧");
40     }
41 }

View Code

运行结果：

孙悟空降魔！
猪八戒牵白龙马!
沙和尚拿行李！
唐僧骑马!

改动大，将原有的1个类变成了4个类，还需要修改客户端代码！！！

 

 1 package danyizhize;
 2 
 3 class Person {
 4     public void Work(String name) {
 5         if ("孙悟空".equals(name)) {
 6             System.out.println(name + "降魔！");
 7         } else if ("猪八戒".equals(name)) {
 8             System.out.println(name + "牵白龙马！");
 9         } else if ("沙和尚".equals(name)) {
10             System.out.println(name + "拿行李！");
11         } else if ("唐僧".equals(name)) {
12             System.out.println(name + "骑马！");
13         }
14     }
15 }
16 
17 public class DanYiZhiZe {
18 
19     public static void main(String[] args) {
20         // TODO Auto-generated method stub
21         Person person = new Person();
22 
23         person.Work("孙悟空");
24         person.Work("猪八戒");
25         person.Work("沙和尚");
26         person.Work("唐僧");
27     }
28 }

View Code

运行结果：

孙悟空降魔！
猪八戒牵白龙马！
沙和尚拿行李！
唐僧骑马！

如果再增加其他人，很有可能变成孙悟空做饭，操作简单，却存在隐患！！！

 

 1 package danyizhize;
 2 
 3 class Person {
 4     public void XiangMo(String name) {
 5         System.out.println(name + "降魔！");
 6     }
 7 
 8     public void XingLi(String name) {
 9         System.out.println(name + "拿行李！");
10     }
11 
12     public void QianMa(String name) {
13         System.out.println(name + "牵白龙马!");
14     }
15 
16     public void QiMa(String name) {
17         System.out.println(name + "骑马!");
18     }
19 }
20 
21 public class DanYiZhiZe {
22 
23     public static void main(String[] args) {
24         // TODO Auto-generated method stub
25         Person person = new Person();
26         person.XiangMo("孙悟空");
27         person.QianMa("猪八戒");
28         person.XingLi("沙和尚");
29         person.QiMa("唐僧");
30     }
31 }

View Code

孙悟空降魔！
猪八戒牵白龙马!
沙和尚拿行李！
唐僧骑马!

 

需要足够简单的逻辑，才可以在代码上违反单一职责原则；

需要类中方法数量足够少，才可以在方法级别上违反单一职责原则。