asp.net下载文件几种方式

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();
  }