尚硅谷设计模式学习(22)---[状态模式(State Pattern)]

Posted 2021-10-25 小智RE0

尚硅谷传送门==>B站尚硅谷Java设计模式

❤❤❤感谢尚硅谷❤❤❤

最近开始计划学习一下设计模式了,加油!!!

---

状态模式

来解决对象在多种状态转换时，需要对外输出不同的行为的问题。状态和行为一一对应，状态之间可以相互转换.

原理图

当一个对象的内在状态改变时，允许改变其行为，这个对象看起来就像是改变了这个类.
当一个对象有很多种状态，状态之间还会相互转换，对不同的状态要求有不同的行为，可考虑用状态模式

解决一个案例

APP抽奖活动 具体要求:

• 1假如每参加一次这个活动要扣除用户50积分，中奖概率是10%
• 2奖品数量固定，抽完就不能抽奖
• 3活动有四个状态: 可以抽奖、不能抽奖、发放奖品和奖品领完

类图分析

抽奖状态类State

/**
 * @author by CSDN@小智RE0
 */
//状态抽象类;
public abstract class State {
    //扣除积分方法;
    public abstract void deductIntegral();

    //抽奖;
    public abstract boolean raffle();

    //发放奖品;
    public abstract void offeringPrizes();
}

待抽奖状态类NotRaffleState

/**
 * @author by CSDN@小智RE0
 */

//不许抽奖状态(待抽奖状态);
public class NotRaffleState extends State{

    //关联抽奖活动;
    private RaffleActivity raffleActivity;
    //初始化;
    public NotRaffleState(RaffleActivity raffleActivity) {
        this.raffleActivity = raffleActivity;
    }

    //扣除积分;
    @Override
    public void deductIntegral() {
        System.out.println("扣掉50分啦,可以去抽奖啦!!!");
        //状态转换==>可抽奖状态;
        raffleActivity.setState(raffleActivity.getRaffleState());
    }

    @Override
    public boolean raffle() {
        System.out.println("对不起,扣除积分才能参与抽奖!");
        return false;
    }

    @Override
    public void offeringPrizes() {
        System.out.println("没参与抽奖,不发奖品!!!");
    }
}

抽奖参与状态类RaffleState

/**
 * @author by CSDN@小智RE0
 */
//抽奖状态;
public class RaffleState extends State{
    //关联抽奖活动;
    private RaffleActivity raffleActivity;
    //初始化;
    public RaffleState(RaffleActivity raffleActivity) {
        this.raffleActivity = raffleActivity;
    }

    //扣除积分;
    @Override
    public void deductIntegral() {
        System.out.println("已扣过积分,参与抽奖吧1");
    }

    @Override
    public boolean raffle() {
        System.out.println("要抽奖啦!----->");
        Random random = new Random();
        int num = random.nextInt(10);
        if(num == 5){
            //只有10%的中奖机会; ==> 发放奖品状态;
            raffleActivity.setState(raffleActivity.getOfferPrizesState());
            return true;
        }else{
            System.out.println("没中奖啊,再接再厉===================>");
            //跳转到不能抽奖的 状态;
            raffleActivity.setState(raffleActivity.getNotRaffleState());
            return false;
        }

    }

    @Override
    public void offeringPrizes() {
        System.out.println("没中奖,不给发奖品");
    }
}

领奖状态类OfferPrizesState

/**
 * @author by CSDN@小智RE0
 */
//发放奖品状态;
public class OfferPrizesState extends State {
    //关联抽奖活动;
    private RaffleActivity raffleActivity;
    //初始化;
    public OfferPrizesState(RaffleActivity raffleActivity) {
        this.raffleActivity = raffleActivity;
    }

    //扣积分方法;
    @Override
    public void deductIntegral() {
        System.out.println("发奖品呢,扣什么积分啊!!!");
    }

    //抽奖发放
    @Override
    public boolean raffle() {
        System.out.println("您已经在领奖了,还抽奖干嘛!");
        return false;
    }

    @Override
    public void offeringPrizes() {
        if(raffleActivity.getCount()>0){
            System.out.println("<==请领取您的奖品==>ლ(´ڡ`ლ)好吃的.");
            //跳转到不能抽奖状态;
            raffleActivity.setState(raffleActivity.getNotRaffleState());
        }else {
            System.out.println("o((⊙﹏⊙))o抱歉,您来晚了,没奖品了,要不您在试试别的活动!");
            //跳转到没有奖品状态;
            raffleActivity.setState(raffleActivity.getNoPrizesState());
        }

    }
}

奖品发放结束状态类NoPrizesState

/**
 * @author by CSDN@小智RE0
 */
//奖品发完 状态;
public class NoPrizesState extends State{
    //关联抽奖活动;
    private RaffleActivity raffleActivity;
    //初始化;
    public NoPrizesState(RaffleActivity raffleActivity) {
        this.raffleActivity = raffleActivity;
    }

    //扣除积分发放;
    @Override
    public void deductIntegral() {
        System.out.println("奖品没了,就不扣您的积分了");
    }

    @Override
    public boolean raffle() {
        System.out.println("奖品都没了,您还抽什么奖啊!");
        return false;
    }

    @Override
    public void offeringPrizes() {
        System.out.println("奖品都没了,不用来领奖了!");
    }
}

抽奖活动类RaffleActivity

/**
 * @author by CSDN@小智RE0
 */

//抽奖活动;
public class RaffleActivity {
    //抽奖状态;
    State state=null;
    //奖品数量;
    int count=0;

    //初始化;定义奖品数量;不能抽奖;
    public RaffleActivity(int count) {
        System.out.println("快来玩啊,抽奖活动开始啦");
        this.state = getNotRaffleState();
        this.count = count;
    }

    //不能抽奖状态;
    State notRaffleState = new NotRaffleState(this);
    //可抽奖状态;
    State raffleState = new RaffleState(this);
    //发放奖品状态;
    State offerPrizesState = new OfferPrizesState(this);
    //奖品发放结束状态;
    State noPrizesState = new NoPrizesState(this);

    //扣除积分;
    public void deductIntegral(){
        state.deductIntegral();
    }

    //抽奖;
    public void raffle(){
        if(state.raffle()){
            //抽奖了就做好发奖品的准备吧,
         state.offeringPrizes();
        }
    }

    //getter ,setter方法;
    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 getNotRaffleState() {
        return notRaffleState;
    }

    public void setNotRaffleState(State notRaffleState) {
        this.notRaffleState = notRaffleState;
    }

    public State getRaffleState() {
        return raffleState;
    }

    public void setRaffleState(State raffleState) {
        this.raffleState = raffleState;
    }

    public State getOfferPrizesState() {
        return offerPrizesState;
    }

    public void setOfferPrizesState(State offerPrizesState) {
        this.offerPrizesState = offerPrizesState;
    }

    public State getNoPrizesState() {
        return noPrizesState;
    }

    public void setNoPrizesState(State noPrizesState) {
        this.noPrizesState = noPrizesState;
    }
}

模拟客户端

/**
 * @author by CSDN@小智RE0
 */
public class Client {
    public static void main(String[] args) {
        //开始活动;
        RaffleActivity raffleActivity = new RaffleActivity(1);
        //抽奖10次;
        for (int i = 0; i < 10; i++) {
            System.out.println("第"+(i+1)+"次抽奖--->");
            //扣积分;抽奖
            raffleActivity.deductIntegral();
            raffleActivity.raffle();
        }
    }
}

---