.NET 同步 异步 委托

1、定义委托：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Web;

namespace DelegateWebApp
{

    /// <summary>
    /// 定义委托
    /// </summary>
    /// <param name="i"></param>
    /// <param name="y"></param>
    /// <returns></returns>
    public  delegate int SumDelegate(int i,int y);

    public class CounterService
    {
        
        public int Sum(int i,int y)
        {
            return i + y;
        }


        /// <summary>
        /// 异步等待
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        public int WaitSum(int a, int b)
        {

            for (var i = 0; i < 50; i++)
            {
                System.Threading.Thread.Sleep(1000);
                WriteLog("WaitSum 执行时间:" + DateTime.Now.TimeOfDay.ToString() + "
");
              
            }

            return a + b;
        }


        /// <summary>
        /// 日志记录
        /// </summary>
        /// <param name="msg"></param>
        public  static void WriteLog(string msg)
        {
            // 此处不能通过 Server.Map 去获取对象
            string realPath = AppDomain.CurrentDomain.BaseDirectory+"/log.txt";
            FileStream fsWriter = null;
            if (!File.Exists(realPath))
            {
                fsWriter = new FileStream(realPath, FileMode.Create);
            }
            else
            {
                fsWriter = new FileStream(realPath, FileMode.Append);
            }
            StreamWriter sw = new StreamWriter(fsWriter);//实现一个类，向流中写入字符
            sw.WriteLine(msg);//写入流
            sw.Close();//类关闭
            fsWriter.Close();//流关闭
        }
    }
}

　　

2、调用方法：

  同步：

  

   CounterService.WriteLog("同步调用开始:" + DateTime.Now.TimeOfDay.ToString() + "
");
            CounterService counterService=new CounterService ();
            SumDelegate sumDellegate = new SumDelegate(counterService.Sum);
            lbResult.Text=sumDellegate(10,20).ToString();
            CounterService.WriteLog("同步调用完成:" + DateTime.Now.TimeOfDay.ToString() + "
");

　　

  异步：

   

  Action<IAsyncResult> action=(x)=>{
                CounterService.WriteLog("异步调用Action开始:" + DateTime.Now.TimeOfDay.ToString() + "
");

                SumDelegate handler = (SumDelegate)((System.Runtime.Remoting.Messaging.AsyncResult)x).AsyncDelegate;
                lbResult.Text = handler.EndInvoke(x).ToString() + ";" + x.AsyncState;
                CounterService.WriteLog("异步调用Action结束:" + DateTime.Now.TimeOfDay.ToString() + "
");
          
            };

            CounterService.WriteLog("结果输出时间:" + DateTime.Now.TimeOfDay.ToString() + "
");
            lbSync.Text = "结果输出，但异步委托还在执行";

            CounterService.WriteLog("异步调用开始:" + DateTime.Now.TimeOfDay.ToString() + "
");

            CounterService counterService = new CounterService();
            SumDelegate sumDellegate = new SumDelegate(counterService.WaitSum);
            IAsyncResult asyncResult = sumDellegate.BeginInvoke(10, 30, new AsyncCallback(action), "OK:" + DateTime.Now.TimeOfDay.ToString());
            CounterService.WriteLog("异步调用完成:" + DateTime.Now.TimeOfDay.ToString() + "
");

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