一、简介
1、定义
状态模式 (state pattern)是一种行为型设计模式,允许对象在内部状态改变时改变它的行为。通过定义状态接口和具体状态类,将对象的状态和行为分开,使得状态改变时可以改变行为。
2、状态模式的结构
状态模式涉及以下几个角色:
state(状态接口):定义了状态类的共同接口,所有具体的状态类都实现这个接口。
concretestate(具体状态类):每个具体的状态类实现了state接口,并定义了在该状态下的具体行为。
context(上下文):上下文类维护一个当前状态的引用,它通常会委托给具体的状态类来执行相应的状态切换。
二、java实现案例
1、电灯开关状态案例
/** * @description: 状态接口 * @date: 2025-02-07 17:09 * @author: gaoyufei **/ public interface state { void handle(switch context); } /** * @description: 关灯状态 * @date: 2025-02-07 17:12 * @author: gaoyufei **/ public class closestate implements state{ @override public void handle(switch switcher) { switcher.setstate(new openstate()); system.out.println("开灯了"); } } /** * @description: 开灯状态 * @date: 2025-02-07 17:11 * @author: gaoyufei **/ public class openstate implements state{ @override public void handle(switch switcher) { switcher.setstate(new closestate()); system.out.println("关灯了"); } } /** * @description: 开关,持有灯的状态 * @date: 2025-02-07 17:08 * @author: gaoyufei **/ public class switch { private state state; public switch(state state){ this.state=state; } public void setstate(state state){ this.state=state; } public void press(){ state.handle(this); } } /** * @description: 操作人 * @date: 2025-02-07 17:14 * @author: gaoyufei **/ public class operator { public static void main(string[] args) throws interruptedexception { switch switcher=new switch(new closestate());//初始状态是关灯 //模拟每隔1秒按压一下开关 while (true){ thread.sleep(1000); switcher.press(); } } }
2、番茄工作法状态案例
/** * @description: 番茄状态接口 * @date: 2025-02-08 10:49 * @author: gaoyufei **/ public interface tomatostate { void deal(worker worker); } /** * @description: 番茄-工作状态类 * @date: 2025-02-08 10:51 * @author: gaoyufei **/ public class worktomatostate implements tomatostate { @override public void deal(worker worker) { system.out.println("休息结束了,开始工作吧"); try { thread.sleep(25*60*1000); } catch (interruptedexception e) { e.printstacktrace(); } system.out.println("工作了25分钟"); worker.settomatostate(new resttomatostate()); } } /** * @description: 番茄-休息状态类 * @date: 2025-02-08 10:53 * @author: gaoyufei **/ public class resttomatostate implements tomatostate{ @override public void deal(worker worker) { system.out.println("工作结束了,好好休息吧"); try { thread.sleep(5*60*1000); } catch (interruptedexception e) { e.printstacktrace(); } system.out.println("休息了5分钟"); worker.settomatostate(new worktomatostate()); } } /** * @description: 工作者 * @date: 2025-02-08 10:51 * @author: gaoyufei **/ public class worker { private tomatostate tomatostate; public worker(tomatostate tomatostate){ this.tomatostate=tomatostate; } public void settomatostate(tomatostate tomatostate){ this.tomatostate=tomatostate; } public void starttomatoclock(){ this.tomatostate.deal(this); } } /** * @description: 客户端 * @date: 2025-02-08 11:02 * @author: gaoyufei **/ public class client { public static void main(string[] args) { worker worker=new worker(new worktomatostate()); while (true){ worker.starttomatoclock(); } } }
3、电梯状态案例
这是一个简单的电梯系统。电梯的状态有关门、开门、上升、下降、停止。每个状态下电梯的行为不同。通过状态模式,根据电梯的不同状态执行不同的行为。
/** * @description: 电梯状态接口 * @date: 2025-02-08 9:02 * @author: gaoyufei **/ public interface elevatorstate { void opendoor(); void closedoor(); void moveup(); void movedown(); void stop(); } /** * @description: 关门状态 * @date: 2025-02-08 9:05 * @author: gaoyufei **/ public class closestate implements elevatorstate { private elevator elevator; public closestate(elevator elevator){ this.elevator=elevator; } @override public void opendoor() { system.out.println("电梯门开了"); elevator.setcurrentstate(elevator.getopenstate()); } @override public void closedoor() { system.out.println("电梯门已经关了"); } @override public void moveup() { system.out.println("电梯上升"); elevator.setcurrentstate(elevator.getmovingupstate()); } @override public void movedown() { system.out.println("电梯下降"); elevator.setcurrentstate(elevator.getmovingdownstate()); } @override public void stop() { system.out.println("电梯停止"); elevator.setcurrentstate(elevator.getstopstate()); } } /** * @description: 开门状态 * @date: 2025-02-08 9:07 * @author: gaoyufei **/ public class openstate implements elevatorstate{ private elevator elevator; public openstate(elevator elevator){ this.elevator=elevator; } @override public void opendoor() { system.out.println("电梯门已经打开"); } @override public void closedoor() { system.out.println("电梯门关了"); elevator.setcurrentstate(elevator.getclosestate()); } @override public void moveup() { system.out.println("电梯门打开状态,不能上升"); } @override public void movedown() { system.out.println("电梯门打开状态,不能下降"); } @override public void stop() { system.out.println("电梯门打开状态,不能变换为停止状态"); } } /** * @description: 停止状态 * @date: 2025-02-08 9:59 * @author: gaoyufei **/ public class stopstate implements elevatorstate{ private elevator elevator; public stopstate(elevator elevator){ this.elevator=elevator; } @override public void opendoor() { system.out.println("电梯门开了"); elevator.setcurrentstate(elevator.getopenstate()); } @override public void closedoor() { system.out.println("电梯门关了"); elevator.setcurrentstate(elevator.getclosestate()); } @override public void moveup() { system.out.println("电梯上升"); elevator.setcurrentstate(elevator.getmovingupstate()); } @override public void movedown() { system.out.println("电梯下降"); elevator.setcurrentstate(elevator.getmovingdownstate()); } @override public void stop() { system.out.println("电梯停止"); } } /** * @description: 上升状态 * @date: 2025-02-08 9:07 * @author: gaoyufei **/ public class movingupstate implements elevatorstate{ private elevator elevator; public movingupstate(elevator elevator){ this.elevator=elevator; } @override public void opendoor() { system.out.println("电梯正在上升,不能开门"); } @override public void closedoor() { system.out.println("电梯已经关门"); } @override public void moveup() { system.out.println("电梯正在上升"); } @override public void movedown() { system.out.println("电梯下降"); elevator.setcurrentstate(elevator.getmovingdownstate()); } @override public void stop() { system.out.println("电梯停止"); elevator.setcurrentstate(elevator.getstopstate()); } } /** * @description: 下降状态 * @date: 2025-02-08 9:08 * @author: gaoyufei **/ public class movingdownstate implements elevatorstate{ private elevator elevator; public movingdownstate(elevator elevator){ this.elevator=elevator; } @override public void opendoor() { system.out.println("电梯正在下降,不能开门"); } @override public void closedoor() { system.out.println("电梯正在下降,已经关门了"); } @override public void moveup() { system.out.println("电梯上升"); elevator.setcurrentstate(elevator.getmovingupstate()); } @override public void movedown() { system.out.println("电梯正在下降"); } @override public void stop() { system.out.println("电梯停止"); elevator.setcurrentstate(elevator.getstopstate()); } } /** * @description: 电梯 * @date: 2025-02-08 9:04 * @author: gaoyufei **/ public class elevator { private elevatorstate closestate; private elevatorstate openstate; private elevatorstate movingdownstate; private elevatorstate movingupstate; private elevatorstate stopstate; private elevatorstate currentstate; public elevator(){ closestate=new closestate(this); openstate=new openstate(this); movingdownstate=new movingdownstate(this); movingupstate=new movingupstate(this); stopstate=new stopstate(this); currentstate=closestate;// 默认初始状态为关闭状态 } public void setcurrentstate(elevatorstate currentstate) { this.currentstate = currentstate; } public elevatorstate getclosestate() { return closestate; } public elevatorstate getopenstate() { return openstate; } public elevatorstate getmovingdownstate() { return movingdownstate; } public elevatorstate getmovingupstate() { return movingupstate; } public elevatorstate getstopstate() { return stopstate; } public void opendoor(){ currentstate.opendoor(); } public void closedoor(){ currentstate.closedoor(); } public void moveup(){ currentstate.moveup(); } public void movedown(){ currentstate.movedown(); } public void stop(){ currentstate.stop(); } } /** * @description: 客户端 * @date: 2025-02-08 9:29 * @author: gaoyufei **/ public class client { public static void main(string[] args) { //初始关闭状态 elevator elevator=new elevator(); //关门 elevator.closedoor();//输出 电梯门已经关了 //开门 elevator.opendoor();//输出 电梯门开了 //上升 elevator.moveup();//输出 电梯门打开状态不能上升 //关门 elevator.closedoor();//输出 电梯门关了 //上升 elevator.moveup();//输出 电梯上升 //关门 elevator.closedoor();//输出 电梯已经关门 //下降 elevator.movedown();//输出 电梯下降 //停止 elevator.stop();//输出 电梯停止 //开门 elevator.opendoor();//输出 电梯门开了 //停止 elevator.stop();//输出 电梯门打开状态,不能变换为停止状态 } }
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