Observer观察者设计模式

Observer设计模式主要包括以下两种对象:

(1)被观察对象:Subject,它往往包含其他对象感兴趣的东西,上面例子中热水器中就是Subject(被监视对象);

(2)观察对象:Observer,它观察着Subject,当Subject中的某件事发生后,会告知Observer,Obersver会采取相应的行动。上面例子中显示器和报警器就是观察对象,当油箱中温度大于95°时,报警器和显示器就会做出相应的警报;

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace ObserverApp
{class Program{static void Main(string[] args){Oil o = new Oil();o.BoiledEvent += new Alarm().MakeAlarm;//先往Oil对象中注册事件o.BoiledEvent += new Display().ShowMsg;//先往Oil对象中注册事件o.BoilWater();//执行主要方法,等到条件合适在触发上面注册的事件
        }}/// <summary>/// Subject被观察对象   ---Oil热水器/// </summary>internal class Oil{/// <summary>/// 牌子/// </summary>public string brand = "Nick";/// <summary>/// 价格/// </summary>public int price = 1000;public delegate void BoiledHandler(object obj, EventArgs args);public event BoiledHandler BoiledEvent;/// <summary>/// 将观察者感兴趣的信息通过实例传递过去/// </summary>public class BoilEventArgs : EventArgs {public int Temperature { get; set; }public BoilEventArgs(int temperature) {this.Temperature = temperature;}}public void BoilWater() {for (int i = 0; i <= 100; i++) {if (i >= 95) {BoilEventArgs args = new BoilEventArgs(i);BoiledEvent(this, args);//当温度达到95度及以上的时候,触发所有订阅该事件的观察者的方法
                }}}}/// <summary>/// Observer观察对象   ---警报器/// </summary>internal class Alarm {public void MakeAlarm(object sender,EventArgs args) {Oil o = (Oil)sender;ObserverApp.Oil.BoilEventArgs a = (ObserverApp.Oil.BoilEventArgs)args;Console.WriteLine("Alarm:嘀嘀嘀,水已经 {0} 度了,当前热水器的牌子是{1},价格是{2}",a.Temperature, o.brand, o.price);}}/// <summary>/// Observer观察对象   ---显示器/// </summary>internal class Display{public void ShowMsg(object sender, EventArgs args){Oil o = (Oil)sender;ObserverApp.Oil.BoilEventArgs a = (ObserverApp.Oil.BoilEventArgs)args;Console.WriteLine("Display:水已烧开,当前温度:{0}度,当前热水器的牌子是{1},价格是{2}", a.Temperature, o.brand, o.price);Console.ReadKey();}}
}