C#自定义事件的写法

C#事件基于委托
1、事件声明完整格式范例：

class Program
{
	static void Main(string[] args)
	{
		Customer customer = new Customer();//新建顾客
		Waiter waiter = new Waiter();//新建服务员
		customer.Order += waiter.Action;//服务员订阅顾客下单事件
		customer.Action();//顾客下单
		customer.PayTheBill();//顾客付钱
		Console.ReadKey();
	}
}
//自定义事件参数，默认以EventArgs结尾，需要继承EventArgs类
public class OrderEventArgs:EventArgs
{
	public string DishName { get; set; }
	public string Size { get; set; }
}
//声明委托类型
public delegate void OrderEventHandler(Customer customer, OrderEventArgs e);
public class Customer
{
	public double Bill { get; set; }
	public void PayTheBill()
	{
		Console.WriteLine("I will pay ${0}.",Bill);
	}
	//声明委托字段
	private OrderEventHandler orderEventHandler;
	//定义事件
	public event OrderEventHandler Order
	{
		add
		{
			orderEventHandler += value;
		}
		remove
		{
			orderEventHandler -= value;
		}
	}
	public void Action()
	{
		Console.WriteLine("Walk into the restaurant.");
		Console.WriteLine("Sit down.");
		for (int i = 0; i < 5; i++)
		{
			Console.WriteLine("Let me think...");
			System.Threading.Thread.Sleep(1000);
		}
		OnOrder("ManHanQuanXi", "large");
	}
	//触发事件的方法一般命名为On???,并且不能是public,一般是protected，触发事件必须由对象自己触发，不能由外部触发
	private void OnOrder(string dishName,string size)
	{
		if (Order != null)
		{
			OrderEventArgs e = new OrderEventArgs();
	       	e.DishName = dishName;
  			e.Size = size;
    		//触发事件
        	Order.Invoke(this, e);
   		}
	}
}
public class Waiter
{
	public void Action(Customer customer, OrderEventArgs e)
	{
		Console.WriteLine("I will serve you the dish : {0}.",e.DishName);
		double price = 10;
		switch (e.Size)
		{
			case "small":
				price *= 0.5;
				break;
			case "large":
				price *= 1.5;
				break;
			default:
				break;
		}
		customer.Bill += price;//返回顾客订单价格
	}
}

2、事件声明简化格式范例：

class Program
{
	static void Main(string[] args)
	{
		Customer customer = new Customer();//新建顾客
		Waiter waiter = new Waiter();//新建服务员
		customer.Order += waiter.Action;//服务员订阅顾客下单事件
		customer.Action();//顾客下单
		customer.PayTheBill();//顾客付钱
		Console.ReadKey();
	}
}
//事件参数，默认以EventArgs结尾，需要继承EventArgs类
public class OrderEventArgs:EventArgs
{
	public string DishName { get; set; }
	public string Size { get; set; }
}
//声明委托类型
public delegate void OrderEventHandler(Customer customer, OrderEventArgs e);
public class Customer
{
	public double Bill { get; set; }
	public void PayTheBill()
	{
		Console.WriteLine("I will pay ${0}.",Bill);
	}
	//定义事件
	public event OrderEventHandler Order;
	public void Action()
	{
		Console.WriteLine("Walk into the restaurant.");
		Console.WriteLine("Sit down.");
		for (int i = 0; i < 5; i++)
		{
			Console.WriteLine("Let me think...");
			System.Threading.Thread.Sleep(1000);
		}
		OnOrder("ManHanQuanXi", "large");
	}
	//触发事件的方法一般命名为On???,并且不能是public,一般是protected，触发事件必须由对象自己触发，不能由外部触发
	private void OnOrder(string dishName,string size)
	{
		if (Order != null)
		{
			OrderEventArgs e = new OrderEventArgs();
	       	e.DishName = dishName;
  			e.Size = size;
    		//触发事件
        	Order.Invoke(this, e);
   		}
	}
}
public class Waiter
{
	public void Action(Customer customer, OrderEventArgs e)
	{
		Console.WriteLine("I will serve you the dish : {0}.",e.DishName);
		double price = 10;
		switch (e.Size)
		{
			case "small":
				price *= 0.5;
				break;
			case "large":
				price *= 1.5;
				break;
			default:
				break;
		}
		customer.Bill += price;//返回顾客订单价格
	}
}

3、事件声明通常不需要自定义委托类型，一般使用系统自带的EventHandler 类型

class Program
{
	static void Main(string[] args)
	{
		Customer customer = new Customer();//新建顾客
		Waiter waiter = new Waiter();//新建服务员
		customer.Order += waiter.Action;//服务员订阅顾客下单事件
		customer.Action();//顾客下单
		customer.PayTheBill();//顾客付钱
		Console.ReadKey();
	}
}
//事件参数，默认以EventArgs结尾，需要继承EventArgs类
public class OrderEventArgs:EventArgs
{
	public string DishName { get; set; }
	public string Size { get; set; }
}
public class Customer
{
	public double Bill { get; set; }
	public void PayTheBill()
	{
		Console.WriteLine("I will pay ${0}.",Bill);
	}
	//定义事件
	public event EventHandler Order;
	public void Action()
	{
		Console.WriteLine("Walk into the restaurant.");
		Console.WriteLine("Sit down.");
		for (int i = 0; i < 5; i++)
		{
			Console.WriteLine("Let me think...");
			System.Threading.Thread.Sleep(1000);
		}
		OnOrder("ManHanQuanXi", "large");
	}
	//触发事件的方法一般命名为On???,并且不能是public,一般是protected，触发事件必须由对象自己触发，不能由外部触发
	private void OnOrder(string dishName,string size)
	{
		if (Order != null)
		{
			OrderEventArgs e = new OrderEventArgs();
	       	e.DishName = dishName;
  			e.Size = size;
    		//触发事件
        	Order.Invoke(this, e);
   		}
	}
}
public class Waiter
{
	public void Action(object sender, EventArgs e)
	{
		Customer customer = sender as Customer;
		OrderEventArgs e2 = e as OrderEventArgs;
		Console.WriteLine("I will serve you the dish : {0}.",e2.DishName);
		double price = 10;
		switch (e2.Size)
		{
			case "small":
				price *= 0.5;
				break;
			case "large":
				price *= 1.5;
				break;
			default:
				break;
		}
		customer.Bill += price;//返回顾客订单价格
	}
}