【转载】C# 从服务器下载文件

支持并尊重原创！原文地址：https://www.cnblogs.com/GoCircle/p/6429136.html

 一、//TransmitFile实现下载
     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/z.zip");
         Response.TransmitFile(filename);
     }

 二、//WriteFile实现下载
     protected void Button2_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();
     }

 三、   //WriteFile分块下载
     protected void Button3_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 = ;//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 >  && Response.IsClientConnected)
             {
                 int lengthRead = iStream.Read(buffer, , Convert.ToInt32(ChunkSize));//读取的大小
                 Response.OutputStream.Write(buffer, , lengthRead);
                 Response.Flush();
                 dataLengthToRead = dataLengthToRead - lengthRead;
             }
             Response.Close();
         }
     }

 四、//流方式下载
     protected void Button4_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, , 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 = ;
 　　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 = ;
     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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