状态模式

题目描述

在我做这道题目的时候，学习了一下设计模式，于是复习一下！
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这道题我是用状态模式写的，那么状态模式是什么呢？
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说明：
Context（状态拥有者）：是一个具有“状态”属性的类，可以定制相关的接口，让外界能够得知状态的改变或者通过操作让状态改变。
State（状态接口类）：制定状态的接口，负责规范Context在特定状态下要表现的行为。
ConcreteState（具体状态类）：继承自State，实现Context在特定状态下该有的行为。

我们可以看出对于上面那道题，我们应该设计一个状态接口State、4个不同状态实现这个接口PlayState、StopState、FastForwardState、FastRewardState，同时在其中设置相应的方法，比如有时候，方法执行之时会改变状态！
代码如下：

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（第一次画类图，很多不规范！）：
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代码如下

创建接口State：

package VideoPlayer;

/**
 * @Description:
 * @Author: Liu Jianwei
 * @Date: 2021/2/28 11:41
 */
public interface State {
    void MidClick();
    void FastForwardClick();
    void FastRewardClick();
}

创建四种状态：

package VideoPlayer;

public class PlayState implements State {

    private VideoPlayer mVideoPlayer;
    public PlayState(VideoPlayer mVideoPlayer) {
        this.mVideoPlayer = mVideoPlayer;
    }

//    点击中间后，进入待播状态
    @Override
    public void MidClick() {
        System.out.println("已进入待播状态");
        mVideoPlayer.setState(mVideoPlayer.mStopState);
    }

//    点击快进后 进入快进状态
    @Override
    public void FastForwardClick() {
        System.out.println("已快进");
        mVideoPlayer.setState(mVideoPlayer.mFastForwardState);
    }

//  点击快退后 进入快退状态
    @Override
    public void FastRewardClick() {
        System.out.println("已快退");
        mVideoPlayer.setState(mVideoPlayer.mFastRewardState);
    }
}
package VideoPlayer;

public class StopState implements State {
    private VideoPlayer mVideoPlay;
    public StopState(VideoPlayer mVideoPlay) {
        this.mVideoPlay = mVideoPlay;
    }

//    点击后 切换到正在播放状态
    @Override
    public void MidClick() {
        System.out.println("正在播放");
        mVideoPlay.setState(mVideoPlay.mPlayState);
    }
//    暂停状态下点快进 只快进时间 依然暂停
    @Override
    public void FastForwardClick() {
        System.out.println("快进15秒");
    }
//    同上
    @Override
    public void FastRewardClick() {
        System.out.println("快退15秒");
    }
}
package VideoPlayer;

public class FastForwardState implements State{
    private VideoPlayer mVideoPlayer;
    public FastForwardState(VideoPlayer mVideoPlayer) {
        this.mVideoPlayer = mVideoPlayer;
    }

//    暂停
    @Override
    public void MidClick() {
        System.out.println("已进入待播状态");
        mVideoPlayer.setState(mVideoPlayer.mStopState);
    }
//    点一下返回正常播放状态
    @Override
    public void FastForwardClick() {
        System.out.println("已恢复正常速度");
        mVideoPlayer.setState(mVideoPlayer.mPlayState);
    }
//    去快退状态
    @Override
    public void FastRewardClick() {
        System.out.println("已快退");
        mVideoPlayer.setState(mVideoPlayer.mFastRewardState);
    }
}
package VideoPlayer;

public class FastRewardState implements State {
    private VideoPlayer mVideoPlayer;

    public FastRewardState(VideoPlayer mVideoPlayer) {
        this.mVideoPlayer = mVideoPlayer;
    }

//   进入暂停
    @Override
    public void MidClick() {
        System.out.println("已进入待播装态");
        mVideoPlayer.setState(mVideoPlayer.mStopState);
    }
//    进入快进状态
    @Override
    public void FastForwardClick() {
        System.out.println("已进入快进状态");
        mVideoPlayer.setState(mVideoPlayer.mFastForwardState);
    }

//      快退状态再点快退 会进入到正常播放的状态
    @Override
    public void FastRewardClick() {
        System.out.println("已取消快退");
        mVideoPlayer.setState(mVideoPlayer.mPlayState);

    }
}

主界面：

package VideoPlayer;

public class VideoPlayer {
    State mPlayState;
    State mStopState;
    State mFastForwardState;
    State mFastRewardState;
    private State state;

//    播放器初始化  为播放状态
    public VideoPlayer() {
        mPlayState = new PlayState(this);
        mStopState = new StopState(this);
        mFastForwardState = new FastForwardState(this);
        mFastRewardState = new FastRewardState(this);
        state = mPlayState;
    }

    public State getState() {
        return state;
    }

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

    public void PrintState() {
        System.out.println(state);
    }

    //    中间点击的三个方法实现 播放/暂停、快进、快退
    public void MidClick() {
        state.MidClick();
    }

    public void FastForwardClick() {
        state.FastForwardClick();
    }

    public void FastRewardClick() {
        state.FastRewardClick();
    }
}

测试：

package VideoPlayer;

public class MainTest {
    public static void main(String[] args) {
        VideoPlayer ***ew VideoPlayer();
//      进入待播状态
        vp.MidClick();
//        快进
        vp.FastForwardClick();
//        快退
        vp.FastRewardClick();
    }
}