//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();  }