protected void Button1_Click(object sender, EventArgs e)   {   /*   微软为Response对象提供了一个新的方法TransmitFile来解决使用Response.BinaryWrite   下载超过400mb的文件时导致Aspnet_wp.exe进程回收而无法成功下载的问题。   代码如下：   */   Response.ContentType = "application/x-zip-compressed";   Response.AddHeader("Content-Disposition", "attachment;filename=z.zip");   string filename = Server.MapPath("DownLoad/aaa.zip");   Response.TransmitFile(filename);   }   //WriteFile实现下载   protected void Button2_Click(object sender, EventArgs e)   {   /*   using System.IO;   */   string fileName ="aaa.zip";//客户端保存的文件名   string filePath=Server.MapPath("DownLoad/aaa.zip");//路径   FileInfo fileInfo = new FileInfo(filePath);   Response.Clear();   Response.ClearContent();   Response.ClearHeaders();   Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);   Response.AddHeader("Content-Length", fileInfo.Length.ToString());   Response.AddHeader("Content-Transfer-Encoding", "binary");   Response.ContentType = "application/octet-stream";   Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");   Response.WriteFile(fileInfo.FullName);   Response.Flush();   Response.End();   }   //WriteFile分块下载   protected void Button3_Click(object sender, EventArgs e)   {   string fileName = "aaa.zip";//客户端保存的文件名   string filePath = Server.MapPath("DownLoad/aaa.zip");//路径   System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);   if (fileInfo.Exists == true)   {   const long ChunkSize = 102400;//100K 每次读取文件，只读取100Ｋ，这样可以缓解服务器的压力   byte[] buffer = new byte[ChunkSize];   Response.Clear();   System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);   long dataLengthToRead = iStream.Length;//获取下载的文件总大小   Response.ContentType = "application/octet-stream";   Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName));   while (dataLengthToRead > 0 && Response.IsClientConnected)   {   int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//读取的大小   Response.OutputStream.Write(buffer, 0, lengthRead);   Response.Flush();   dataLengthToRead = dataLengthToRead - lengthRead;   }   Response.Close();   }   }   //流方式下载   protected void Button4_Click(object sender, EventArgs e)   {   string fileName = "aaa.zip";//客户端保存的文件名   string filePath = Server.MapPath("DownLoad/aaa.zip");//路径   //以字符流的形式下载文件   FileStream fs = new FileStream(filePath, FileMode.Open);   byte[] bytes = new byte[(int)fs.Length];   fs.Read(bytes, 0, bytes.Length);   fs.Close();   Response.ContentType = "application/octet-stream";   //通知浏览器下载文件而不是打开   Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));   Response.BinaryWrite(bytes);   Response.Flush();   Response.End();   }