java design pattern - state pattern

这里的 这个state pattern 的代码就很不错：

https://sourcemaking.com/design_patterns/state/java/1

另外一个比较简单的代码：

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1. package statepattern;
   
2. 
   
3. interface MobileState{
   
4.     public void getState();
   
5. }
   
6. 
   
7. class Ringing implements MobileState{
   
8. 
   
9.     @Override
   
10.     public void getState(){
    
11.         System.out.println("Mobile is in ringing state");
    
12.     }
    
13. }
    
14. 
    
15. class Silent implements MobileState{
    
16. 
    
17.     @Override
    
18.     public void getState(){
    
19.         System.out.println("Mobile is in silent state");
    
20.     }
    
21. }
    
22. 
    
23. class Vibration implements MobileState{
    
24. 
    
25.     @Override
    
26.     public void getState(){
    
27.         System.out.println("Mobile is in vibration state");
    
28.     }
    
29. }
    
30. 
    
31. class MobileContext implements MobileState{
    
32.     private MobileState ms;
    
33. 
    
34.     public void setMObileState(MobileState ms){
    
35.         this.ms = ms;
    
36.     }
    
37. 
    
38.     //constructor
    
39.     public MobileContext(MobileState ms){
    
40.         this.ms = ms;
    
41.     }
    
42. 
    
43.     public void getState(){
    
44.         ms.getState();
    
45.     }
    
46. }
    
47. 
    
48. public class StatePatternDemo1 {
    
49.     public static void main(String[] args){
    
50.         MobileContext ctx = new MobileContext(new Ringing());
    
51.         ctx.getState();
    
52.         ctx.setMObileState(new Vibration());
    
53.         ctx.getState();
    
54.         ctx.setMObileState(new Silent());
    
55.         ctx.getState();
    
56. 
    
57.     }
    
58. }