using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.IO;

//文件异步操作

namespace FileAsynchronousOperation

{

    class Program

    {

        static void Main(string[] args)

        {

            //实例化MyFile类

            MyFile myFile = new MyFile();

            //定义参数

            string filePath = "D:\\testasy.txt";

            string msg = "helloworld";

            //调用异步操作方法

            myFile.AsynchronousOperation(filePath,msg);

        }

    }

    /// <summary>

    /// 文件

    /// </summary>

    class MyFile

    {

        /// <summary>

        /// 文件异步操作

        /// </summary>

        /// <param name="filePath">文件路径</param>

        /// <param name="msg">写入内容</param>

        public void AsynchronousOperation(string filePath,string msg)

        {

            FileStream fileSteam = null;

            FileInfo fileinfo = new FileInfo(filePath);

            //判断文件是否存在

            if (!fileinfo.Exists)

            {

                fileSteam = fileinfo.Create();

                Console.WriteLine("创建文件{0}", filePath);

                fileSteam.Close();

            }

            fileSteam = new FileStream(filePath, FileMode.Open, FileAccess.Write, FileShare.None, , true);

            Console.WriteLine("开启异步操作{0}", fileSteam.IsAsync);

            byte[] buffer = Encoding.Default.GetBytes(msg);

            //开始执行异步操作

            IAsyncResult asynncResult = fileSteam.BeginWrite(buffer,, buffer.Length, new AsyncCallback(EndWriteCallBack), fileSteam);

            Console.WriteLine("开始异步写入请稍候...");

            Console.Read();

        }

        /// <summary>

        /// 回调函数

        /// </summary>

        /// <param name="asyncResult">状态</param>

        public void EndWriteCallBack(IAsyncResult asyncResult)

        {

            Console.WriteLine("异步写入开始...");

            FileStream stream = asyncResult.AsyncState as FileStream;//转化为FileStream类型

            if (stream!=null)

            {

                stream.EndWrite(asyncResult);

                stream.Close();

            }

            Console.WriteLine("写入完成");

        }

    }

}