行为型模式之状态模式

 1 /**
 2  * State
 3  * 抽象状态类
 4  */
 5 public interface State {
 6    public void doAction(Context context);
 7 }
 8 
 9 /**
10  * ConcreteState
11  * 具体状态类
12  */
13 public class StartState implements State {
14  
15    @Override
16    public void doAction(Context context) {
17       System.out.println("Player is in start state");
18       context.setState(this); 
19    }
20  
21    @Override
22    public String toString(){
23       return "Start State";
24    }
25 }
26 
27 /**
28  * ConcreteState
29  * 具体状态类
30  */
31 public class StopState implements State {
32  
33    @Override
34    public void doAction(Context context) {
35       System.out.println("Player is in stop state");
36       context.setState(this); 
37    }
38  
39    @Override
40    public String toString(){
41       return "Stop State";
42    }
43 }
44 
45 /**
46  * Context
47  * 环境类
48  */
49 public class Context {
50    private State state;
51  
52    public Context(){
53       state = null;
54    }
55  
56    public void setState(State state){
57       this.state = state;     
58    }
59  
60    public State getState(){
61       return state;
62    }
63 }
64 
65 /**
66  * client
67  */
68 public class Client {
69 
70     public static void main(String[] args) {
71         Context context = new Context();
72 
73         StartState startState = new StartState();
74         startState.doAction(context);
75 
76         System.out.println(context.getState().toString());
77 
78         StopState stopState = new StopState();
79         stopState.doAction(context);
80 
81         System.out.println(context.getState().toString());
82     }
83 }