protected void Button1_Click(object sender, EventArgs e)
  {
  /*
   Microsoft is Response The object provides 1 A new approach TransmitFile To solve the problem of using Response.BinaryWrite
   Download over 400mb When the file is caused Aspnet_wp.exe The process was recalled and could not be successfully downloaded.
   The code is as follows:
  */
  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 download
  protected void Button2_Click(object sender, EventArgs e)
  {
  /*
  using System.IO;

  */
  string fileName ="aaa.zip";// File name saved by the client
  string filePath=Server.MapPath("DownLoad/aaa.zip");// The path
  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 Block download
  protected void Button3_Click(object sender, EventArgs e)
  {
  string fileName = "aaa.zip";// File name saved by the client
  string filePath = Server.MapPath("DownLoad/aaa.zip");// The path
  System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);
  if (fileInfo.Exists == true)
  {
  const long ChunkSize = 102400;//100K  Each time the file is read, read only 100 K, which can relieve the pressure on the server
  byte[] buffer = new byte[ChunkSize];
  Response.Clear();
  System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);
  long dataLengthToRead = iStream.Length;// Gets the total size of the downloaded file
  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));// Read size
  Response.OutputStream.Write(buffer, 0, lengthRead);
  Response.Flush();
  dataLengthToRead = dataLengthToRead - lengthRead;
  }
  Response.Close();
  }
  }
  // Streaming download
  protected void Button4_Click(object sender, EventArgs e)
  {
  string fileName = "aaa.zip";// File name saved by the client
  string filePath = Server.MapPath("DownLoad/aaa.zip");// The path
  // Download the file as a stream of characters
  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";
  // Notify the browser to download the file instead of opening it
  Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
  Response.BinaryWrite(bytes);
  Response.Flush();
  Response.End();
  }