一个对象存在多个状态(不同状态下行为不同),且状态可相互转换
图片.png
状态类:
package com.geely.design.pattern.behavioral.state;
/**
* @Author: wenbaipei
* @Date: 2019/11/30 19:36
* @Version 1.0
*/
public abstract class CourseVideoState {
protected CourseVideoContext courseVideoContext;
public void setCourseVideoContext(CourseVideoContext courseVideoContext) {
this.courseVideoContext = courseVideoContext;
}
public abstract void play();
public abstract void speed();
public abstract void pause();
public abstract void stop();
}
package com.geely.design.pattern.behavioral.state;
/**
* @Author: wenbaipei
* @Date: 2019/11/30 19:39
* @Version 1.0
*/
public class PlayState extends CourseVideoState {
@Override
public void play() {
System.out.println("正常播放课程视频状态");
}
@Override
public void speed() {
courseVideoContext.setCourseVideoState(CourseVideoContext.SPEED_STATE);
}
@Override
public void pause() {
courseVideoContext.setCourseVideoState(CourseVideoContext.PAUSE_STATE);
}
@Override
public void stop() {
courseVideoContext.setCourseVideoState(CourseVideoContext.STOP_STATE);
}
}
package com.geely.design.pattern.behavioral.state;
/**
* @Author: wenbaipei
* @Date: 2019/11/30 19:39
* @Version 1.0
*/
public class SpeedState extends CourseVideoState {
@Override
public void play() {
courseVideoContext.setCourseVideoState(CourseVideoContext.PLAY_STATE);
}
@Override
public void speed() {
System.out.println("快进播放课程视频状态");
}
@Override
public void pause() {
courseVideoContext.setCourseVideoState(CourseVideoContext.PAUSE_STATE);
}
@Override
public void stop() {
courseVideoContext.setCourseVideoState(CourseVideoContext.STOP_STATE);
}
}
/**
* @Author: wenbaipei
* @Date: 2019/11/30 19:39
* @Version 1.0
*/
public class PauseState extends CourseVideoState {
@Override
public void play() {
courseVideoContext.setCourseVideoState(CourseVideoContext.PLAY_STATE);
}
@Override
public void speed() {
courseVideoContext.setCourseVideoState(CourseVideoContext.SPEED_STATE);
}
@Override
public void pause() {
System.out.println("暂停播放课程视频状态");
}
@Override
public void stop() {
courseVideoContext.setCourseVideoState(CourseVideoContext.STOP_STATE);
}
}
package com.geely.design.pattern.behavioral.state;
/**
* @Author: wenbaipei
* @Date: 2019/11/30 19:39
* @Version 1.0
*/
public class StopState extends CourseVideoState {
@Override
public void play() {
courseVideoContext.setCourseVideoState(CourseVideoContext.PLAY_STATE);
}
@Override
public void speed() {
System.out.println("ERROR 停止状态不能快进");
}
@Override
public void pause() {
System.out.println("ERROR 停止状态不能暂停");
}
@Override
public void stop() {
System.out.println("停止播放课程视频状态");
}
}
上下文状态:
package com.geely.design.pattern.behavioral.state;
/**
* @Author: wenbaipei
* @Date: 2019/11/30 19:37
* @Version 1.0
*/
public class CourseVideoContext {
private CourseVideoState courseVideoState;
public final static PlayState PLAY_STATE = new PlayState();
public final static SpeedState SPEED_STATE = new SpeedState();
public final static PauseState PAUSE_STATE = new PauseState();
public final static StopState STOP_STATE = new StopState();
public CourseVideoState getCourseVideoState() {
return courseVideoState;
}
public void setCourseVideoState(CourseVideoState courseVideoState) {
this.courseVideoState = courseVideoState;
this.courseVideoState.setCourseVideoContext(this);
}
public void play(){
this.courseVideoState.play();
}
public void speed(){
this.courseVideoState.speed();
}
public void pause(){
this.courseVideoState.pause();
}
public void stop(){
this.courseVideoState.stop();
}
}
测试类:
package com.geely.design.pattern.behavioral.state;
/**
* @Author: wenbaipei
* @Date: 2019/11/30 19:54
* @Version 1.0
*/
public class Test {
public static void main(String[] args) {
CourseVideoContext courseVideoContext = new CourseVideoContext();
courseVideoContext.setCourseVideoState(CourseVideoContext.PLAY_STATE);
System.out.println("当前状态:"+courseVideoContext.getCourseVideoState().getClass().getSimpleName());
courseVideoContext.pause();
System.out.println("当前状态:"+courseVideoContext.getCourseVideoState().getClass().getSimpleName());
courseVideoContext.speed();
System.out.println("当前状态:"+courseVideoContext.getCourseVideoState().getClass().getSimpleName());
courseVideoContext.stop();
System.out.println("当前状态:"+courseVideoContext.getCourseVideoState().getClass().getSimpleName());
courseVideoContext.speed();
}
}
结果:
图片.png
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