Head Frist 设计模式11-状态模式模式

如果饿了就吃，困了就睡，渴了就喝，人生就太无趣了
代码地址：https://github.com/keer123456789/MY_STUDY_LIFE/tree/master/src/main/java/study/Module/Module_State

1.定义

1.1概念

状态模式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的类。

1.2类图

将所有的状态抽象出一个共同接口state,让不同的状态都实现这个接口，这样就可以实现不同状态的转换
Context类拥有一些状态，一旦有人调用request()方法，就委托到状态state来实现。
ConcreteState类处理来自Context的请求。

2.例子（糖果机）

给一个投币糖果机进行程序设计。每次投25美分，就可以获得一个口香糖。

2.1 状态图

现在需要给一个糖果机的程序进行设计，如图2：状态图
一共是4个状态：

没有25分钱
有25分钱
糖果售罄
售出糖果

有5个动作：每一个动作都是糖果机的接口，调用每一个动作，都会造成状态的转换

投入25美分
转动曲柄
退回25美分
发放糖果
填入糖果

2.2 类图

如图3：

根据刚才得分析，将能改变状态的5个动作进行抽象，形成State接口,接口方法分别是：insertQuarter()投币，ejectQuart()退币, turnCrank()转动曲柄，dispense()分配糖果，refill()添加糖果
一共有四个状态，都实现State接口，每个状态对不同的动作接口做出不同的反应。

2.3 分析流程

如图4

糖果机的状态为没有25美分NoQuarter，此时有投币动作insertQuarter()时，将动作委托到NoQuarter状态，进行状态转换，切换到HasQuarter有25美分状态
糖果机接收到转动曲柄动作turnCrank(),将动作委托到当前状态，状态进行转换，切换到Sold售出糖果状态
糖果机接收到出售糖果动作dispense(),将动作委托到当前状态，状态进行转换，切换到NoQuarter无25美分状态

3.代码

3.1 状态接口和实现类

/**
 * @BelongsProject: MY_STUDY_LIFE
 * @BelongsPackage: study.Module.Module_State
 * @Author: keer
 * @CreateTime: 2020-03-09 14:29
 * @Description: 状态接口
 */
public interface State {
    /**
     * 投入25美分
     */
    void insertQuarter();

    /**
     * 退回25美分
     */
    void ejectQuarter();

    /**
     * 转动曲柄
     */
    void turnCrank();

    /**
     * 分配糖果
     */
    void dispense();

    /**
     * 重新添加糖果
     */
    void refill();
}




/**
 * @BelongsProject: MY_STUDY_LIFE
 * @BelongsPackage: study.Module.Module_State
 * @Author: keer
 * @CreateTime: 2020-03-09 14:43
 * @Description: 没有25美分状态
 */
public class NoQuarterState implements State {
    GumballMachine gumballMachine;

    public NoQuarterState(GumballMachine gumballMachine) {
        this.gumballMachine = gumballMachine;
    }

    @Override
    public void insertQuarter() {
        System.out.println("You inserted a quarter");
        gumballMachine.setState(gumballMachine.getHasQuarterState());
    }

    @Override
    public void ejectQuarter() {
        System.out.println("You haven't inserted 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");
    }

    @Override
    public void refill() {

    }

    @Override
    public String toString() {
        return "waiting for quarter";
    }
}

/**
 * @BelongsProject: MY_STUDY_LIFE
 * @BelongsPackage: study.Module.Module_State
 * @Author: keer
 * @CreateTime: 2020-03-09 14:45
 * @Description: 有25美分状态
 */
public class HasQuarterState implements State{
    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");
    }

    @Override
    public void refill() {

    }

    @Override
    public String toString() {
        return "waiting for turn of crank";
    }
}

/**
 * @BelongsProject: MY_STUDY_LIFE
 * @BelongsPackage: study.Module.Module_State
 * @Author: keer
 * @CreateTime: 2020-03-09 14:33
 * @Description: 售出糖果状态
 */
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());
        }
    }

    @Override
    public void refill() {

    }

    @Override
    public String toString() {
        return "dispensing a gumball";
    }
}



/**
 * @BelongsProject: MY_STUDY_LIFE
 * @BelongsPackage: study.Module.Module_State
 * @Author: keer
 * @CreateTime: 2020-03-09 14:40
 * @Description: 售罄状态
 */
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");
    }

    @Override
    public void refill() {
        gumballMachine.setState(gumballMachine.getNoQuarterState());
    }

    @Override
    public String toString() {
        return "sold out";
    }
}

3.2 糖果机代码

**
 * @BelongsProject: MY_STUDY_LIFE
 * @BelongsPackage: study.Module.Module_State
 * @Author: keer
 * @CreateTime: 2020-03-09 14:35
 * @Description: 糖果机
 */
public class GumballMachine {

    State soldOutState;
    State noQuarterState;
    State hasQuarterState;
    State soldState;

    State state;
    int count = 0;

    public GumballMachine(int numberGumballs) {
        soldOutState = new SoldOutState(this);
        noQuarterState = new NoQuarterState(this);
        hasQuarterState = new HasQuarterState(this);
        soldState = new SoldState(this);

        this.count = numberGumballs;
        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();
    }

    void releaseBall() {
        System.out.println("A gumball comes rolling out the slot...");
        if (count != 0) {
            count = count - 1;
        }
    }

    int getCount() {
        return count;
    }

    void refill(int count) {
        this.count += count;
        System.out.println("The gumball machine was just refilled; it's new count is: " + this.count);
        state.refill();
    }

    void setState(State state) {
        this.state = state;
    }

    public State getState() {
        return state;
    }

    public State getSoldOutState() {
        return soldOutState;
    }

    public State getNoQuarterState() {
        return noQuarterState;
    }

    public State getHasQuarterState() {
        return hasQuarterState;
    }

    public State getSoldState() {
        return soldState;
    }

    @Override
    public String toString() {
        StringBuffer result = new StringBuffer();
        result.append("\nMighty Gumball, Inc.");
        result.append("\nJava-enabled Standing Gumball Model #2020");
        result.append("\nInventory: " + count + " gumball");
        if (count != 1) {
            result.append("s");
        }
        result.append("\n");
        result.append("Machine is " + state + "\n");
        return result.toString();
    }
}

3.3 测试代码

/**
 * @BelongsProject: MY_STUDY_LIFE
 * @BelongsPackage: study.Module.Module_State
 * @Author: keer
 * @CreateTime: 2020-03-09 14:53
 * @Description: 测试类
 */
public class GumballMachineTestDrive {
    public static void main(String[] args) {
        GumballMachine gumballMachine = new GumballMachine(2);

        System.out.println(gumballMachine);

        gumballMachine.insertQuarter();
        gumballMachine.turnCrank();

        System.out.println(gumballMachine);

        gumballMachine.insertQuarter();
        gumballMachine.turnCrank();
        gumballMachine.insertQuarter();
        gumballMachine.turnCrank();

        gumballMachine.refill(5);
        gumballMachine.insertQuarter();
        gumballMachine.turnCrank();

        System.out.println(gumballMachine);
    }
}

设计模式10——状态模式

Head Frist 设计模式11-状态模式模式

1.定义

1.1概念

1.2类图

2.例子（糖果机）

2.1 状态图

2.2 类图

2.3 分析流程

3.代码

3.1 状态接口和实现类

3.2 糖果机代码

3.3 测试代码

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