【C#设计模式(21)——状态模式(State Pattern)】

前言

状态模式:在对象内部发生改变时改变其行为，使得对象在不同的状态下具有不同的行为表现。

代码

 #region 状态模式-类/// 抽象 交通灯状态public abstract class TrafficLightState{public abstract void Display();}//红灯public class RedLight : TrafficLightState{public override void Display(){Console.WriteLine("红灯停");}}//绿灯public class GreenLight : TrafficLightState{public override void Display(){Console.WriteLine("绿灯行");}}//黄灯public class YellowLight : TrafficLightState{public override void Display(){Console.WriteLine("黄灯等待");}}//交通灯上下文public class TrafficLightContext{private TrafficLightState trafficLight;public TrafficLightContext(){trafficLight = new RedLight();}public void SetTrafficLightState(TrafficLightState trafficLight){this.trafficLight = trafficLight;}public void Display(){trafficLight.Display();}}#endregion#region 状态模式-枚举//交通灯状态枚举public enum TrafficLightEnum{Red,Green,Yellow}//交通灯枚举状态显示设置类public class TrafficLightEnumState{private TrafficLightEnum state;public void SetState(TrafficLightEnum state){this.state = state;}public void Display(){switch (state){case TrafficLightEnum.Red:Console.WriteLine("红灯停");break;case TrafficLightEnum.Green:Console.WriteLine("绿灯行");break;case TrafficLightEnum.Yellow:Console.WriteLine("黄灯等待");break;}}}//交通灯上下文（枚举设置）public class TrafficLightEnumContext{private TrafficLightEnumState trafficLight;public TrafficLightEnumContext(){trafficLight = new TrafficLightEnumState();trafficLight.SetState(TrafficLightEnum.Red);}public void SetTrafficLightState(TrafficLightEnum state){trafficLight.SetState(state);}public void Display(){trafficLight.Display();}}#endregion/** 行为型模式：Behavioral Pattern* 状态模式：State Pattern*/
internal class Program
{/** 行为型模式：Behavioral Pattern* 状态模式：State Pattern*/static void Main(string[] args){//类模式Console.WriteLine("类模式......");TrafficLightContext trafficLight = new TrafficLightContext();trafficLight.Display();trafficLight.SetTrafficLightState(new GreenLight());trafficLight.Display();trafficLight.SetTrafficLightState(new YellowLight());trafficLight.Display();//枚举模式Console.WriteLine("枚举模式......");TrafficLightEnumContext trafficLightEnumContext = new TrafficLightEnumContext();trafficLightEnumContext.Display();trafficLightEnumContext.SetTrafficLightState(TrafficLightEnum.Green);trafficLightEnumContext.Display();trafficLightEnumContext.SetTrafficLightState(TrafficLightEnum.Yellow);trafficLightEnumContext.Display();Console.ReadLine();}
}

运行结果