代码如下,我不太明白:
- this.orderEventHandler.Invoke(this,e)是如何触发public event OrderEventHandler Order事件的?
- this.orderEventHandler.Invoke(this,e)这里的this是什么意思?
- public event OrderEventHandler Order下面定义的add、remove、+=value是什么意思?
namespace Event3
{
class Program
{
static void Main(string[] args)
{
Customer customer = new Customer();
Waiter waiter = new Waiter();
customer.Order += waiter.Action;
customer.Action();
customer.PayBill();
Console.ReadLine();
}
}
public class OrderEventArgs:EventArgs
{
public string DishName { get; set; }
public string Size { get; set; }
}
public delegate void OrderEventHandler(Customer customer, OrderEventArgs e);
public class Customer
{
private OrderEventHandler orderEventHandler;
public event OrderEventHandler Order
{
add
{
this.orderEventHandler += value;
}
remove
{
this.orderEventHandler -= value;
}
}
public double Bill { get; set; }
public void PayBill()
{
Console.WriteLine("I will pay ${0}",this.Bill);
}
public void WalkIn()
{
Console.WriteLine("Walk into the restaurant.");
}
public void SitDown()
{
Console.WriteLine("Sit down.");
}
public void Think()
{
Console.WriteLine("Let me think...");
Thread.Sleep(1000);
if (this.orderEventHandler!=null)
{
OrderEventArgs e = new OrderEventArgs();
e.DishName = "Kongpao Chicken";
e.Size = "large";
this.orderEventHandler.Invoke(this,e);
}
}
public void Action()
{
this.WalkIn();
this.SitDown();
this.Think();
}
}
public class Waiter
{
public void Action(Customer customer, OrderEventArgs e)
{
Console.WriteLine("I will serve you dish-{0}",e.DishName);
double price = 10;
switch(e.Size)
{
case "small":
price = price * 0.5;
break;
case "large":
price = price * 1.5;
break;
default:
break;
}
customer.Bill += price;
}
}
}