大家帮我完善一下这个状态模式的小例子。

   1. //我们先创建一个State接口,所有的状态都必须实现这个接口
   2. public interface State {
   3.     public void insertQuarter();
   4.     public void ejectQuarter();
   5.     public void turnCrank();
   6.     public void dispense();
   7. }
   8. //实现我们的状态类
   9. public class NoQuarterState implements State {  //先实现State接口
  10.     GumballMachine gumballMachine;
  11.     //通过构造器得到糖果机的引用
  12.     public NoQuarterState(GumballMachine gumballMachine) {
  13.     this.gumballMachine = gumballMachine;
  14.     }
  15.     //还是那几个方法
  16.     public void insertQuarter() {
  17.         System.out.println("You inserted a quarter");
  18.         //你马上会看到这里如何工作的
  19.         gumballMachine.setState(gumballMachine.getHasQuarterState());
  20.     }
  21.     public void ejectQuarter() {
  22.         System.out.println("You haven't inserted a quarter");
  23.     }
  24.     public void turnCrank() {
  25.         System.out.println("You turned, but there's no quarter");
  26.      }
  27.     public void dispense() {
  28.         System.out.println("You need to pay first");
  29.     }
  30.     public String toString() {
  31.         return "waiting for quarter";
  32.     }
  33. }
  34. //完整的糖果机类
  35. public class GumballMachine {
  36.     //所有的状态都在这里
  37.     State soldOutState;
  38.     State noQuarterState;
  39.     State hasQuarterState;
  40.     State soldState;
  41.     State winnerState;//十次抽中一次的游戏,新的状态
  42.     //以及实例变量state
  43.     State state = soldOutState;
  44.     int count = 0;//记录糖果数量
  45.     public GumballMachine(int numberGumballs) {
  46.         soldOutState = new SoldOutState(this);  //每一种状态也都创建一个状态实例
  47.         noQuarterState = new NoQuarterState(this);
  48.         hasQuarterState = new HasQuarterState(this);
  49.         soldState = new SoldState(this);
  50.         this.count = numberGumballs;
  51.         if (numberGumballs > 0) {    //如果超过0颗糖果,状态设为noQuarterState
  52.             state = noQuarterState;
  53.         }
  54.     }
  55.     //委托给当前状态
  56.     public void insertQuarter() {
  57.         state.insertQuarter();
  58.     }
  59.     public void ejectQuarter() {
  60.         state.ejectQuarter();
  61.     }
  62.     //dispense()是一个内部动作方法,用户不可以直接要求机器发放糖果
  63.     public void turnCrank() {
  64.         state.turnCrank();
  65.         state.dispense();
  66.     }
  67.     //允许其他的对象将机器状态转换到不同的状态
  68.     void setState(State state) {
  69.         this.state = state;
  70.     }
  71.     //辅助方法释放出糖果,并将count实例变量值减1
  72.     void releaseBall() {
  73.         System.out.println("A gumball comes rolling out the slot...");
  74.         if (count != 0) {
  75.             count = count - 1;
  76.         }
  77.     }
  78.     int getCount() {
  79.         return count;
  80.     }
  81.     void refill(int count) {
  82.         this.count = count;
  83.         state = noQuarterState;
  84.     }
  85.     public State getState() {return state;}
  86.     public State getSoldOutState() {return soldOutState;}
  87.     public State getNoQuarterState() {return noQuarterState;}
  88.     public State getHasQuarterState() {return hasQuarterState;}
  89.     public State getSoldState() {return soldState;}
  90.     public State getWinnerState() {return winnerState;}
  91. }
  92. //现在我们来实现HasQuarterState(有25分钱)和SoldState(售出糖果)方法,糖果售完的方法自己写写,这里就不提供了
  93. public class HasQuarterState implements State {
  94.     GumballMachine gumballMachine;
  95.     //增加一个随机数产生器,产生10%的机会
  96.     Random randomWinner = new Random(System.currentTimeMillis());
  97.     public HasQuarterState(GumballMachine gumballMachine) {
  98.         this.gumballMachine = gumballMachine;
  99.     }
100.     public void insertQuarter() {   //这是一个对当前状态不恰当的动作
101.         System.out.println("You can't insert another quarter");
102.     }
103.     public void ejectQuarter() {    //退钱并转换状态到NoQuarterState
104.         System.out.println("Quarter returned");
105.         gumballMachine.setState(gumballMachine.getNoQuarterState());
106.     }
107.     public void turnCrank() {
108.         System.out.println("You turned...");
109.         int winner = randomWinner.nextInt(10);
110.         //决定这个顾客是否赢了
111.         if ((winner == 0) && (gumballMachine.getCount() > 1)) {
112.             gumballMachine.setState(gumballMachine.getWinnerState());
113.         } else {
114.             gumballMachine.setState(gumballMachine.getSoldState());
115.         }
116.     }
117.     public void dispense() {    //这是一个对当前状态不恰当的动作
118.         System.out.println("No gumball dispensed");
119.     }
120. }
121. public class SoldState implements State {
122.     GumballMachine gumballMachine;
123.     public SoldState(GumballMachine gumballMachine) {
124.         this.gumballMachine = gumballMachine;
125.     }
126.     //以下3个方法对此状态来说都是不恰当的
127.     public void insertQuarter() {
128.         System.out.println("Please wait, we're already giving you a gumball");
129.     }
130.     public void ejectQuarter() {
131.         System.out.println("Sorry, you already turned the crank");
132.     }
133.     public void turnCrank() {
134.         System.out.println("Turning twice doesn't get you another gumball!");
135.     }
136.     //首先让机器发放糖果
137.     public void dispense() {
138.         gumballMachine.releaseBall();
139.         if (gumballMachine.getCount() > 0) {
140.             gumballMachine.setState(gumballMachine.getNoQuarterState());
141.         } else {
142.             System.out.println("Oops, out of gumballs!");
143.             gumballMachine.setState(gumballMachine.getSoldOutState());
144.         }
145.     }
146. }
147. //我们再来实现WinnerState类
148. public class WinnerState implements State {
149.     GumballMachine gumballMachine;
150.     //下面都跟SoldState方法一样
151.     public WinnerState(GumballMachine gumballMachine) {
152.         this.gumballMachine = gumballMachine;
153.     }
154.     public void insertQuarter() {
155.         System.out.println("Please wait, we're already giving you a Gumball");
156.     }
157.     public void ejectQuarter() {
158.         System.out.println("Please wait, we're already giving you a Gumball");
159.     }
160.     public void turnCrank() {
161.         System.out.println("Turning again doesn't get you another gumball!");
162.     }
163.     //我们在这里发放出2颗糖果,然后进入NoQuarterState或SoldState
164.     public void dispense() {
165.         System.out.println("YOU'RE A WINNER! You get two gumballs for your quarter");
166.         gumballMachine.releaseBall();
167.         if (gumballMachine.getCount() == 0) {
168.             gumballMachine.setState(gumballMachine.getSoldOutState());
169.         } else {
170.             gumballMachine.releaseBall();
171.             if (gumballMachine.getCount() > 0) {
172.                 gumballMachine.setState(gumballMachine.getNoQuarterState());
173.             } else {
174.                 System.out.println("Oops, out of gumballs!");
175.                 gumballMachine.setState(gumballMachine.getSoldOutState());
176.             }
177.         }
178.     }
179. }
状态模式有时比较if else还难。
我觉得你这个
insertQuarter();
ejectQuarter();
turnCrank();
dispense();  都是动作不是状态,另外状态应该封装在一个context中

调试易

大家帮我完善一下这个状态模式的小例子。

解决方案 »