C#事件用法实例浅析

#region 测试事件1
//EventArgs类
public class CardInfoEventArgs : EventArgs
{
public string Car { get; private set; }
public CardInfoEventArgs(string car)
{
  this.Car = car;
}
}
//触发事件的类
public class CarDealer
{
public event EventHandler<CardInfoEventArgs> NewCardInfo;
public void NewCar(string car)
{
  Console.WriteLine("CarDealer,new car{0}", car);
  //在触发事件之前,需要检查委托NewCardInfo是否不为空。
  //如果没有订阅处理程序,委托就是空
  if (NewCardInfo != null)
  {
 NewCardInfo(this, new CardInfoEventArgs(car));
  }
}
}
//处理事件的类
public class Consumer
{
private string name;
public Consumer(string name)
{
  this.name = name;
}
//处理事件的方法
public void NewCarIsHere(object sender, CardInfoEventArgs e)
{
  Console.WriteLine("{0}:car {1} is new", name, e.Car);
}
}
#endregion
private void button_测试事件1_Click(object sender, EventArgs e)
{
  CarDealer dealer = new CarDealer();
  Consumer michael = new Consumer("Michael");
  dealer.NewCardInfo += michael.NewCarIsHere; //订阅事件
  dealer.NewCar("宝马");
  Consumer nick = new Consumer("Nick");
  dealer.NewCardInfo += nick.NewCarIsHere; //订阅事件
  dealer.NewCar("奔驰");
  dealer.NewCardInfo -= michael.NewCarIsHere; //取消订阅事件
  dealer.NewCar("奥迪");
}