C#自定义事件监听实现方法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApp
{
 /// <summary>
 /// 定义事件
 /// </summary>
 class CustomEvent
 {
  /// <summary>
  /// 定义委托
  /// </summary>
  /// <param name="sender"></param>
  /// <param name="e"></param>
  public delegate void UserRequest(object sender, EventArgs e);
  /// <summary>
  /// 此委托类型的事件
  /// </summary>
  public event UserRequest OnUserRequest;
  public CustomEvent()
  {
   UserEventMonitor uem = new UserEventMonitor(this);
  }
  public void DoRun()
  {
   bool flag = false;
   do
   {
    Console.WriteLine();
    Console.WriteLine("请输入：");
    string result = Console.ReadLine();
    if (result == "1")
    {
     if (OnUserRequest != null)
      OnUserRequest(this, new EventArgs());
    }
   } while (!flag);
  }
 }
 /// <summary>
 /// 事件监听
 /// </summary>
 class UserEventMonitor
 {
  public UserEventMonitor(CustomEvent cem)
  {
   // cem.OnUserRequest += ShowMessage;
   cem.OnUserRequest += delegate
   {
    Console.WriteLine("hello word!!");
   };
  }
  public void ShowMessage(object sender, EventArgs e)
  {
   Console.WriteLine("hello word!!");
  }
 }
 /// <summary>
 /// 调用类
 /// </summary>
 public class Run
 {
  static void Main(string[] args)
  {
   CustomEvent cem = new CustomEvent();
   cem.DoRun();
   Console.ReadLine();
  }
 }
}