C# 委托与事件简单应用

C# 事件简单应用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TestIO
{
    public delegate double PriceHandler();

    public class PriceManager
    {
        public PriceHandler GetPriceHandler;

        //委托处理，当价格高于100元按8.8折计算，其他按原价计算 
        public double GetPrice()
        {
            //GetPriceHandler.GetInvocationList(); 按照此调用顺序,返回多路广播委托的调用列表
            if (GetPriceHandler.GetInvocationList().Count() > 0)
            {
                if (GetPriceHandler() > 100)
                    return GetPriceHandler() * 0.88;
                else
                    return GetPriceHandler();
            }
            return -1;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            PriceManager priceManager = new PriceManager();

            //调用priceManager的GetPrice方法获取价格 
            //直接调用委托的Invoke获取价格，两者进行比较 

            priceManager.GetPriceHandler = new PriceHandler(ComputerPrice);
            Console.WriteLine(string.Format("GetPrice\n  Computer's price is {0}!",
                priceManager.GetPrice()));
            //priceManager.GetPrice();
            Console.WriteLine(string.Format("Invoke\n  Computer's price is {0}!",
                priceManager.GetPriceHandler.Invoke()));

            Console.WriteLine();

            priceManager.GetPriceHandler = new PriceHandler(BookPrice);
            Console.WriteLine(string.Format("GetPrice\n  Book's price is {0}!",
                priceManager.GetPrice()));
            Console.WriteLine(string.Format("Invoke\n  Book's price is {0}!",
                priceManager.GetPriceHandler.Invoke()));

            Console.ReadKey();
        }
        //书本价格为98元 
        public static double BookPrice()
        {
            return 98.0;
        }
        //计算机价格为8800元 
        public static double ComputerPrice()
        {
            return 8800.0;
        }
    } 




}

 

该代码来自cnblogs  http://www.cnblogs.com/philzhou/archive/2012/04/05/2433663.html