java状态模式

 1 定义一个接口
 2 public interface State {
 3     public void handle();
 4 }
 5 
 6 
 7 /**
 8  *具体的状态角色（下单）
 9  * Created by  Administrator
10  */
11 public class PlaceAnOrder implements State {
12     //具体化状态的行为
13     @Override
14     public void handle() {
15         Log.d("doAction","下单");
16     }
17 }
18 
19 /**
20  *具体的状态角色（付款）
21  * Created by  Administrator
22  */
23 public class PayTheOrder implements State {
24     @Override
25     public void handle() {
26         Log.d("doAction","付款");
27     }
28 }
29 
30 /**
31  *具体的状态角色（发货）
32  * Created by  Administrator
33  */
34 public class DeliverGoods implements State {
35     @Override
36     public void handle() {
37         Log.d("doAction","发货");
38     }
39 }
40 
41 public class Context {
42     private State state;
43     public Context() {
44     }
45 
46     public void setState(State state) {
47         this.state = state;
48     }
49 
50     public void doAction() {
51         this.state.handle();
52     }
53 }

 1 Context context=new Context();
 2 //下单
 3 State placeanOrder=new PlaceAnOrder();
 4 context.setState(placeanOrder);
 5 context.doAciton();
 6 
 7 //付款
 8 State paytheOrder=new PayTheOrder();
 9 context.setState(paytheOrder);
10 context.doAciton();
11 
12 //发货
13 State  deliverGoods=new DeliverGoods();
14 context.setState(deliverGoods);
15 context.doAciton();