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notes/设计模式.md

@@ -486,7 +486,7 @@ public class Client {
 
 ### 实现
 
-设计一个要控制，可以控制电灯开关。
+设计一个遥控器，可以控制电灯开关。
 
 <div align="center"> <img src="../pics//e6bded8e-41a0-489a-88a6-638e88ab7666.jpg"/> </div><br>
 
@@ -857,6 +857,306 @@ StatisticsDisplay.update: 1.0 1.0 1.0
 
 ## 8. 状态（State）
 
+### 意图
+
+允许对象在内部状态改变时改变它的行为，对象看起来好像修改了它所属的类。
+
+### 类图
+
+<div align="center"> <img src="../pics//abb3e0d1-c1bd-45d0-8190-73c74a9f6679.png"/> </div><br>
+
+### 实现
+
+糖果销售机有多种状态，每种状态下销售机有不同的行为，状态可以发生转移，使得销售机的行为也发生改变。
+
+<div align="center"> <img src="../pics//396be981-3f2c-4fd9-8101-dbf9c841504b.jpg" width="600"/> </div><br>
+
+```java
+public interface State {
+    /**
+     * 投入 25 分钱
+     */
+    void insertQuarter();
+
+    /**
+     * 退回 25 分钱
+     */
+    void ejectQuarter();
+
+    /**
+     * 转动曲柄
+     */
+    void turnCrank();
+
+    /**
+     * 发放糖果
+     */
+    void dispense();
+}
+```
+
+```java
+public class HasQuarterState implements State {
+
+    private GumballMachine gumballMachine;
+
+    public HasQuarterState(GumballMachine gumballMachine) {
+        this.gumballMachine = gumballMachine;
+    }
+
+    @Override
+    public void insertQuarter() {
+        System.out.println("You can't insert another quarter");
+    }
+
+    @Override
+    public void ejectQuarter() {
+        System.out.println("Quarter returned");
+        gumballMachine.setState(gumballMachine.getNoQuarterState());
+    }
+
+    @Override
+    public void turnCrank() {
+        System.out.println("You turned...");
+        gumballMachine.setState(gumballMachine.getSoldState());
+    }
+
+    @Override
+    public void dispense() {
+        System.out.println("No gumball dispensed");
+    }
+}
+```
+
+```java
+public class NoQuarterState implements State {
+
+    GumballMachine gumballMachine;
+
+    public NoQuarterState(GumballMachine gumballMachine) {
+        this.gumballMachine = gumballMachine;
+    }
+
+    @Override
+    public void insertQuarter() {
+        System.out.println("You insert a quarter");
+        gumballMachine.setState(gumballMachine.getHasQuarterState());
+    }
+
+    @Override
+    public void ejectQuarter() {
+        System.out.println("You haven't insert a quarter");
+    }
+
+    @Override
+    public void turnCrank() {
+        System.out.println("You turned, but there's no quarter");
+    }
+
+    @Override
+    public void dispense() {
+        System.out.println("You need to pay first");
+    }
+}
+```
+
+```java
+public class SoldOutState implements State {
+
+    GumballMachine gumballMachine;
+
+    public SoldOutState(GumballMachine gumballMachine) {
+        this.gumballMachine = gumballMachine;
+    }
+
+    @Override
+    public void insertQuarter() {
+        System.out.println("You can't insert a quarter, the machine is sold out");
+    }
+
+    @Override
+    public void ejectQuarter() {
+        System.out.println("You can't eject, you haven't inserted a quarter yet");
+    }
+
+    @Override
+    public void turnCrank() {
+        System.out.println("You turned, but there are no gumballs");
+    }
+
+    @Override
+    public void dispense() {
+        System.out.println("No gumball dispensed");
+    }
+}
+```
+
+```java
+public class SoldState implements State {
+
+    GumballMachine gumballMachine;
+
+    public SoldState(GumballMachine gumballMachine) {
+        this.gumballMachine = gumballMachine;
+    }
+
+    @Override
+    public void insertQuarter() {
+        System.out.println("Please wait, we're already giving you a gumball");
+    }
+
+    @Override
+    public void ejectQuarter() {
+        System.out.println("Sorry, you already turned the crank");
+    }
+
+    @Override
+    public void turnCrank() {
+        System.out.println("Turning twice doesn't get you another gumball!");
+    }
+
+    @Override
+    public void dispense() {
+        gumballMachine.releaseBall();
+        if (gumballMachine.getCount() > 0) {
+            gumballMachine.setState(gumballMachine.getNoQuarterState());
+        } else {
+            System.out.println("Oops, out of gumballs");
+            gumballMachine.setState(gumballMachine.getSoldOutState());
+        }
+    }
+}
+```
+
+```java
+public class GumballMachine {
+
+    private State soldOutState;
+    private State noQuarterState;
+    private State hasQuarterState;
+    private State soldState;
+
+    private State state;
+    private int count = 0;
+
+    public GumballMachine(int numberGumballs) {
+        count = numberGumballs;
+        soldOutState = new SoldOutState(this);
+        noQuarterState = new NoQuarterState(this);
+        hasQuarterState = new HasQuarterState(this);
+        soldState = new SoldState(this);
+
+        if (numberGumballs > 0) {
+            state = noQuarterState;
+        } else {
+            state = soldOutState;
+        }
+    }
+
+    public void insertQuarter() {
+        state.insertQuarter();
+    }
+
+    public void ejectQuarter() {
+        state.ejectQuarter();
+    }
+
+    public void turnCrank() {
+        state.turnCrank();
+        state.dispense();
+    }
+
+    public void setState(State state) {
+        this.state = state;
+    }
+
+    public void releaseBall() {
+        System.out.println("A gumball comes rolling out the slot...");
+        if (count != 0) {
+            count -= 1;
+        }
+    }
+
+    public State getSoldOutState() {
+        return soldOutState;
+    }
+
+    public State getNoQuarterState() {
+        return noQuarterState;
+    }
+
+    public State getHasQuarterState() {
+        return hasQuarterState;
+    }
+
+    public State getSoldState() {
+        return soldState;
+    }
+
+    public int getCount() {
+        return count;
+    }
+}
+```
+
+```java
+public class Client {
+
+    public static void main(String[] args) {
+        GumballMachine gumballMachine = new GumballMachine(5);
+
+        gumballMachine.insertQuarter();
+        gumballMachine.turnCrank();
+
+        gumballMachine.insertQuarter();
+        gumballMachine.ejectQuarter();
+        gumballMachine.turnCrank();
+
+        gumballMachine.insertQuarter();
+        gumballMachine.turnCrank();
+        gumballMachine.insertQuarter();
+        gumballMachine.turnCrank();
+        gumballMachine.ejectQuarter();
+
+        gumballMachine.insertQuarter();
+        gumballMachine.insertQuarter();
+        gumballMachine.turnCrank();
+        gumballMachine.insertQuarter();
+        gumballMachine.turnCrank();
+        gumballMachine.insertQuarter();
+        gumballMachine.turnCrank();
+    }
+}
+```
+
+```html
+You insert a quarter
+You turned...
+A gumball comes rolling out the slot...
+You insert a quarter
+Quarter returned
+You turned, but there's no quarter
+You need to pay first
+You insert a quarter
+You turned...
+A gumball comes rolling out the slot...
+You insert a quarter
+You turned...
+A gumball comes rolling out the slot...
+You haven't insert a quarter
+You insert a quarter
+You can't insert another quarter
+You turned...
+A gumball comes rolling out the slot...
+You insert a quarter
+You turned...
+A gumball comes rolling out the slot...
+Oops, out of gumballs
+You can't insert a quarter, the machine is sold out
+You turned, but there are no gumballs
+No gumball dispensed
+```
+
 ## 9. 策略（Strategy）
 
 ### 意图
@@ -870,7 +1170,17 @@ StatisticsDisplay.update: 1.0 1.0 1.0
 - Strategy 接口定义了一个算法族，它们都具有 BehaviorInterface() 方法。
 - Context 是使用到该算法族的类，其中的 doSomething() 方法会调用 BehaviorInterface()，setStrategy(in Strategy) 方法可以动态地改变 strategy 对象，也就是说能动态地改变 Context 所使用的算法。
 
-<div align="center"> <img src="../pics//4dc08713-f6fe-424c-a24c-ad5a993a941d.png"/> </div><br>
+<div align="center"> <img src="../pics//b8dd708d-f372-4b04-b828-1dd99021c244.png"/> </div><br>
+
+### 与状态模式的比较
+
+状态模式的类图和策略模式一样，并且都是能够动态改变对象的行为。
+
+但是状态模式是通过状态转移来改变 Context 所组合的 State 对象，而策略模式是通过 Context 本身的决策来改变组合的 Strategy 对象。
+
+所谓的状态转移，是指 Context 在运行过程中由于一些条件发生改变而使得 State 对象发生改变，注意必须要是在运行过程中。
+
+状态模式主要是用来解决状态转移的问题，当状态发生转移了，那么 Context 对象就会改变它的行为；而策略模式主要是用来封装一组可以互相替代的算法族，并且可以根据需要动态地去替换 Context 使用的算法。
 
 ### 实现