net 下载文件的几种方法

1、TransmitFile实现下载

protected void DownLoad_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/z.zip");
     Response.TransmitFile(filename);
 }

2、WriteFile实现下载

  protected void DownLoad2_Click(object sender, EventArgs e)
  {
      /* 
        using System.IO;
      */
      string fileName = "asd.txt";//客户端保存的文件名 
      string filePath = Server.MapPath("DownLoad/aaa.txt");//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();
  }

3、WriteFile分块下载

protected void DownLoad_Click(object sender, EventArgs e)
 {
     string fileName = "aaa.txt";//客户端保存的文件名 
     string filePath = Server.MapPath("DownLoad/aaa.txt");//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();
     }
 }

四、流方式下载

protected void DownLoad4_Click(object sender, EventArgs e)
 {
     string fileName = "aaa.txt";//客户端保存的文件名 
     string filePath = Server.MapPath("DownLoad/aaa.txt");//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();
 }

//----------------------------------------------------------

public void DownloadFile( System.Web.UI.Page WebForm,String FileNameWhenUserDownload ,String FileBody )
{

　　WebForm.Response.ClearHeaders();
　　WebForm.Response.Clear();
　　WebForm.Response.Expires = 0;
　　WebForm.Response.Buffer = true;
　　WebForm.Response.AddHeader("Accept-Language", "zh-tw");
　　//'文件名称
　　WebForm.Response.AddHeader("content-disposition", "attachment; filename='"+System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload, System.Text.Encoding.UTF8)+"'");
　　WebForm.Response.ContentType = "Application/octet-stream";
　　//'文件内容
　　WebForm.Response.Write(FileBody);
   WebForm.Response.End();
}


//上面这段代码是下载一个动态产生的文本文件，若这个文件已经存在于服务器端的实体路径，则可以通过下面的函数：

public void DownloadFileByFilePath( System.Web.UI.Page WebForm,String FileNameWhenUserDownload ,String FilePath )
{
　　WebForm.Response.ClearHeaders();
　　WebForm.Response.Clear();
　　WebForm.Response.Expires = 0;
   WebForm.Response.Buffer = true;
　　WebForm.Response.AddHeader("Accept-Language", "zh-tw");
　　//文件名称
　　WebForm.Response.AddHeader("content-disposition", "attachment; filename='" + System.Web.HttpUtility.UrlEncode(FileNameWhenUserDownload,     System.Text.Encoding.UTF8) +"'" );
　　WebForm.Response.ContentType = "Application/octet-stream";
　　//文件内容
　　WebForm.Response.Write(System.IO.File.Rea}dAllBytes(FilePath));
　　WebForm.Response.End();

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