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设计模式-状态模式

分类: 文章 • 2025-01-08 13:39:58
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。
 要点：
  1.  状态模式允许一个对象基于内部状态而拥有不同的行为。
  2.  和程序状态机不同，状态模式用类代表状态。
  3.  Context会将行为委托给当前状态对象。
  4.  通过将每个状态封装进一个类，我们把以后需要做的任何改变局部化了。
  5.  状态模式和策略模式有相同的类图，但是它们的意图不同。
  6.  策略模式通常会用行为或算法来配置Context类。
  7.  状态模式允许Context随着状态的改变而改变行为。
  8.  状态转换可以有State类或Context类控制。
  9.  使用状态模式通常会导致设计中类的数目大量增加。
  10.  状态类可以被多个Context实例共享。

设计模式-状态模式

public interface State {

    /**
     * 投币业务
     */
    void insertQuarter();

    /**
     * 退币业务
     */
    void ejectQuarter();

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

    /**
     * 发放糖果代码
     */
    void dispense();
}
/**
 * 有钱状态
  */
public class HasQuarterState implements State{
    GumballMachine gumballMachine;
    Random randomWinner = new Random(System.currentTimeMillis());

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

    public void insertQuarter() {
        System.out.println("........你已投过钱了！");
    }

    public void ejectQuarter() {
        System.out.println("........退出客户投入的钱");
        gumballMachine.setState(gumballMachine.getNoQuarterState());
    }

    public void turnCrank() {
        System.out.println("........客户转动曲柄");
        int winner = randomWinner.nextInt(10);
        if ((winner == 0)&&(gumballMachine.getCount()>1)){
            System.out.println("》》》》》》》》获得两次发放机会");
            gumballMachine.setState(gumballMachine.getWinnerState());
        } else {
            gumballMachine.setState(gumballMachine.getSoldState());
        }
    }

    public void dispense() {
        System.out.println("........不能发放糖果");
    }
}
/**
 * 糖果售罄
 */
public class SoldOutState implements State{

    GumballMachine gumballMachine;

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

    public void insertQuarter() {
        System.out.println(".....糖果售罄了，不要投币了");
    }

    public void ejectQuarter() {
        System.out.println(".....售罄糖果不支持退币业务");
    }

    public void turnCrank() {
        System.out.println(".....售罄糖果不支持转动曲柄");
    }

    public void dispense() {
        System.out.println(".....售罄了，不支持发放糖果业务");
    }
}
/**
 * 发放糖果活动
 */
public class WinnerState implements State{

    GumballMachine gumballMachine;

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

    public void insertQuarter() {
        System.out.println(".....正在出糖果，稍后再投");
    }

    public void ejectQuarter() {
        System.out.println(".....正在出售糖果，无法退款");
    }

    public void turnCrank() {
        System.out.println(".....正在售出糖果,稍后操作");
    }

    public void dispense() {
        System.out.println(".....你有两出两颗糖果的机会");
        gumballMachine.releaseBall();
        if (gumballMachine.getCount()==0){
            gumballMachine.setState(gumballMachine.getSoldOutState());
        } else {
            gumballMachine.releaseBall();
            if (gumballMachine.getCount()>0){
                gumballMachine.setState(gumballMachine.getNoQuarterState());
            }else {
                System.out.println("糖果售罄");
                gumballMachine.setState(gumballMachine.getSoldOutState());
            }
        }
    }
}
/**
 * 没投钱
 */
public class NoQuarterState implements State{

    GumballMachine gumballMachine;

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

    public void insertQuarter() {
        System.out.println(".....投钱，改状态");
        gumballMachine.setState(gumballMachine.getHasQuarterState());
    }
    public void ejectQuarter() {
        System.out.println(".....没给钱，不能退钱");
    }

    public void turnCrank() {
        System.out.println(".....没给钱，不能转动曲柄");
    }

    public void dispense() {
        System.out.println(".....没有钱，不发糖果");
    }
}
/**
 * 售出糖果
 */
public class SoldState  implements State{
    GumballMachine gumballMachine;


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

    public void insertQuarter() {
        System.out.println(".....正在售出糖果，请稍后操作");
    }

    public void ejectQuarter() {
        System.out.println(".....售出糖果不能退款");
    }

    public void turnCrank() {
        System.out.println(".....售出糖果不能转动曲柄");
    }

    public void dispense() {
        System.out.println(".....正在售出！");
        gumballMachine.releaseBall();
        if (gumballMachine.getCount()>0){
            gumballMachine.setState(gumballMachine.getNoQuarterState());
        } else {
            System.out.println("糖果卖完了");
            gumballMachine.setState(gumballMachine.getSoldOutState());
        }
    }
}
public class GumballMachine {

    State soldOutState;
    State noQuarterState;
    State hasQuarterState;
    State soldState;
    State winnerState;
    State state = soldOutState;
    
    int count =0;

    public GumballMachine(int numberGumballs) {
        this.soldOutState = new SoldOutState(this);
        this.noQuarterState = new NoQuarterState(this);
        this.hasQuarterState = new HasQuarterState(this);
        this.soldState = new SoldState(this);
        this.count = numberGumballs;
        if(numberGumballs>0){
            state = noQuarterState;
        }
    }

    public void insertQuarter(){
        state.insertQuarter();
    }
    public void ejectQuarter(){
        state.ejectQuarter();
    }
    public void turnCrank(){
        state.turnCrank();
        state.dispense();
    }

    void releaseBall(){
        System.out.println(".。。。。。。。释放糖果，数量-1");
        if (count !=0){
            count = count-1;
        }
    }


    public State getSoldOutState() {
        return soldOutState;
    }

    public void setSoldOutState(State soldOutState) {
        this.soldOutState = soldOutState;
    }

    public State getNoQuarterState() {
        return noQuarterState;
    }

    public void setNoQuarterState(State noQuarterState) {
        this.noQuarterState = noQuarterState;
    }

    public State getHasQuarterState() {
        return hasQuarterState;
    }

    public void setHasQuarterState(State hasQuarterState) {
        this.hasQuarterState = hasQuarterState;
    }

    public State getSoldState() {
        return soldState;
    }

    public void setSoldState(State soldState) {
        this.soldState = soldState;
    }

    public State getState() {
        return state;
    }

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

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

    public State getWinnerState() {
        return winnerState;
    }

    public void setWinnerState(State winnerState) {
        this.winnerState = winnerState;
    }

    @Override
    public String toString() {
        return "GumballMachine{" +
                "soldOutState=" + soldOutState +
                ", noQuarterState=" + noQuarterState +
                ", hasQuarterState=" + hasQuarterState +
                ", soldState=" + soldState +
                ", winnerState=" + winnerState +
                ", state=" + state +
                ", count=" + count +
                '}';
    }
}
public class Test {
    public static void main(String[] args) {
        GumballMachine gumballMachine = new GumballMachine(5);
        System.out.println(".........1:"+gumballMachine.getCount());

        gumballMachine.insertQuarter();
        gumballMachine.turnCrank();
        System.out.println(".........2:"+gumballMachine.getCount());

        gumballMachine.insertQuarter();
        gumballMachine.turnCrank();
        gumballMachine.insertQuarter();
        gumballMachine.turnCrank();
        System.out.println(".........3:"+gumballMachine.getCount());
    }
}
设计模式-状态模式



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