学习委托 代码示例 多播

 

该例子摘自：《C#程序设计教程》--朱毅华等 第132页

 

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

namespace Delegate
{
  
        public class WorkerClass
        {

            public int InstanceMethod(int nID, string sName)
            {

                int retval = 0;

                retval = nID * sName.Length;
                Console.WriteLine("调用InstanceMethod方法");
                return retval;
            }

            public static int StaticMethod(int nID, string sName)
            {
                int retval = 0;

                retval = nID * sName.Length + 2;
                Console.WriteLine("调用StaticMethod方法");
                return retval;
            }

            public delegate int SomeDelegate(int nID, string sName); //--参数等必须和要指向的方法一样

             static void Main(string[] args)
             {
                 WorkerClass wr = new WorkerClass();

                 SomeDelegate d1 = new SomeDelegate(wr.InstanceMethod); //--只是挂钩，尚未执行InstanceMethod方法
                 Console.WriteLine("Invoking delegate InstanceMethod, return={0}", d1(5, "aaa"));  //--先调用执行InstanceMethod方法，再执行该Console方法；

                 SomeDelegate d2 = new SomeDelegate(WorkerClass.StaticMethod);

                 Console.WriteLine("Invoking delegate StaticMethod, return={0}", d2(5, "aaa"));
                 Console.WriteLine("...........");
                 Console.WriteLine("测试多播......");

                 SomeDelegate d3 = d2 + d1;  //--按组装的次序来进行调用；先执行d2,再执行d1
                 Console.WriteLine("d1 And d2 return={0}", d3(5, "aaa"));//--按组装的次序来进行调用；先执行d2,再执行d1

                 Console.WriteLine("..................................");

                 int num_method = d3.GetInvocationList().Length;
                 Console.WriteLine("Number of Methods d3:{0}", num_method);

                 d3 = d3 - d2;
                 Console.WriteLine("d3 - d2 return={0}", d3(5, "aaa"));

                 Console.WriteLine("..................................");
                 num_method = d3.GetInvocationList().Length;    //--该委托里还有几个方法；
                 Console.WriteLine("Number of Methods d3:{0}", num_method);

                 Console.ReadKey();
             }

        }

    }