(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 = ; 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 = ; i <= ; i++)
{
if (i >= )
{
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();
}
}
}
