状态设计模式解读

1. public abstract class State {
2. 
3. //扣除积分
4. public abstract  void deductMoney();
5. 
6. //是否抽中奖品
7. public abstract  boolean raffle();
8. 
9. //发放奖品
10. public abstract  void dispensePrize();
11. 
12. }

1. public class NoRaffleState extends  State{
2. 
3.     RaffleActivity activity;
4. 
5. public NoRaffleState(RaffleActivity activity) {
6. this.activity = activity;
7.     }
8. 
9. @Override
10. public void deductMoney() {
11.         System.out.println("扣除 50 积分成功，您可以抽奖了");
12.         activity.setState(activity.getCanRaffleState());
13.     }
14. 
15. @Override
16. public boolean raffle() {
17.         System.out.println("扣了积分才能抽奖喔！");
18. return false;
19.     }
20. 
21. @Override
22. public void dispensePrize() {
23.         System.out.println("不能发放奖品");
24.     }
25. }

1. //不能抽奖状态
2. public class CanRaffleState extends  State{
3. 
4.     RaffleActivity activity;
5. 
6. public CanRaffleState(RaffleActivity activity) {
7. this.activity = activity;
8.     }
9. 
10. //已经扣除了积分，不能再扣
11. @Override
12. public void deductMoney() {
13.         System.out.println("引进扣除过积分，不用进行积分扣除");
14.     }
15. 
16. 
17. //可以抽奖, 抽完奖后，根据实际情况，改成新的状态
18. @Override
19. public boolean raffle() {
20.         System.out.println("正在抽奖，请稍等！");
21. Random r = new Random();
22. int num = r.nextInt(10);
23. // 10%中奖机会
24. if(num == 0){
25. // 改变活动状态为发放奖品 context
26.             activity.setState(activity.getDispenseState());
27. return true;
28.         }else{
29.             System.out.println("很遗憾没有抽中奖品！");
30. // 改变状态为不能抽奖
31.             activity.setState(activity.getNoRafflleState());
32. return false;
33.         }
34.     }
35. 
36. @Override
37. public void dispensePrize() {
38.         System.out.println("没中奖，不能发放奖品");
39.     }
40. }

1. /**
2.  * 发放奖品状态
3.  */
4. public class DispenseState extends State  {
5. 
6. // 初始化时传入活动引用，发放奖品后改变其状态
7.     RaffleActivity activity;
8. 
9. public DispenseState(RaffleActivity activity) {
10. this.activity = activity;
11.     }
12. 
13. @Override
14. public void deductMoney() {
15.         System.out.println("不能扣除积分");
16.     }
17. 
18. @Override
19. public boolean raffle() {
20.         System.out.println("不能抽奖");
21. return false;
22.     }
23. 
24. @Override
25. public void dispensePrize() {
26. if(activity.getCount() > 0){
27.             System.out.println("恭喜中奖了");
28. // 改变状态为不能抽奖
29.             activity.setState(activity.getNoRafflleState());
30.         }else{
31.             System.out.println("很遗憾，奖品发送完了");
32. // 改变状态为奖品发送完毕, 后面我们就不可以抽奖
33.             activity.setState(activity.getDispensOutState());
34. //System.out.println("抽奖活动结束");
35.         }
36.     }
37. }

1. /**
2.  * 不能抽奖状态
3.  */
4. public class DispenseOutState extends  State{
5. 
6. // 初始化时传入活动引用
7.     RaffleActivity activity;
8. 
9. public DispenseOutState(RaffleActivity activity) {
10. this.activity = activity;
11.     }
12. 
13. @Override
14. public void deductMoney() {
15.         System.out.println("奖品发送完了，请下次再抽奖");
16.     }
17. 
18. @Override
19. public boolean raffle() {
20.         System.out.println("奖品发送完了，请下次再抽奖");
21. return false;
22.     }
23. 
24. @Override
25. public void dispensePrize() {
26.         System.out.println("奖品发送完了，请下次再参加");
27.     }
28. }

1. public class RaffleActivity {
2. //state表示活动当前的状态，是变化
3.     State state=null;
4. //奖品数量
5. int count=0;
6. //四个属性，表示四种状态
7.     State noRafflleState=new NoRaffleState(this);
8.     State canRaffleState=new CanRaffleState(this);
9.     State dispensOutState=new DispenseOutState(this);
10.     State dispenseState= new DispenseState(this);
11. //构造器
12. //1. 初始化当前的状态为 noRafflleState（即不能抽奖的状态）
13. //2. 初始化奖品的数量
14. public RaffleActivity( int count) {
15. this.state = getNoRafflleState();
16. this.count = count;
17.     }
18. //扣分, 调用当前状态的 deductMoney
19. public void debuctMoney(){
20.         state.deductMoney();
21.     }
22. //抽奖
23. public void raffle() {
24. // 如果当前的状态是抽奖成功
25. if(state.raffle()){
26. //领取奖品
27.             state.dispensePrize();
28.         }
29.     }
30. public State getState() {
31. return state;
32.     }
33. public void setState(State state) {
34. this.state = state;
35.     }
36. //这里请大家注意，每领取一次奖品，count--
37. public int getCount() {
38. int curCount = count;
39.         count--;
40. return curCount;
41.     }
42. public void setCount(int count) {
43. this.count = count;
44.     }
45. 
46. public State getNoRafflleState() {
47. return noRafflleState;
48.     }
49. public void setNoRafflleState(State noRafflleState) {
50. this.noRafflleState = noRafflleState;
51.     }
52. public State getCanRaffleState() {
53. return canRaffleState;
54.     }
55. public void setCanRaffleState(State canRaffleState) {
56. this.canRaffleState = canRaffleState;
57.     }
58. public State getDispenseState() {
59. return dispenseState;
60.     }
61. public void setDispenseState(State dispenseState) {
62. this.dispenseState = dispenseState;
63.     }
64. public State getDispensOutState() {
65. return dispensOutState;
66.     }
67. 
68. public void setDispensOutState(State dispensOutState) {
69. this.dispensOutState = dispensOutState;
70.     }
71. }

1. public class ClientTest {
2. public static void main(String[] args) {
3. // 创建活动对象，奖品有 1 个奖品
4. RaffleActivity activity = new RaffleActivity(1);
5. // 我们连续抽 300 次奖
6. for (int i = 0; i < 30; i++) {
7.             System.out.println("--------第" + (i + 1) + "次抽奖----------");
8. // 参加抽奖，第一步点击扣除积分
9.             activity.debuctMoney();
10. // 第二步抽奖
11.             activity.raffle();
12.         }
13.     }
14. }