C# 文件异步操作

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, 4096, 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,0, 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");}}
}

Filestreom 在对文件进行异步操作时，对大数据量读写操作使用 BeginRead 和 Begin 树 rite 方法的效果更好；
而对于数据量较少的读写操作，使川异步方式的速度可能会比同步方式要慢。
所以，你需要针对应用程序的实际情况决定是否要选择异步处理方式。