ASP.NET动态下载文件程序

//打开要下载的文件
        string FilePath = Server.MapPath("~/media/education/" + filename);
        System.IO.FileStream r = new System.IO.FileStream(FilePath, System.IO.FileMode.Open);
        //设置基本信息
        Response.Buffer = false;
        Response.AddHeader("Connection", "Keep-Alive");
        Response.ContentType = "application/octet-stream";
        Response.ContentEncoding = System.Text.Encoding.Default;
 //HttpUtility.UrlEncode解决中文文件名乱码问题
        Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(System.IO.Path.GetFileName(FilePath)) );
        Response.AddHeader("Content-Length", r.Length.ToString());

        while (true)
        {
            //开辟缓冲区空间
            byte[] buffer = new byte[1024];
            //读取文件的数据
            int leng = r.Read(buffer, 0, 1024);
            if (leng == 0)//到文件尾，结束
                break;
            if (leng == 1024)//读出的文件数据长度等于缓冲区长度，直接将缓冲区数据写入
                Response.BinaryWrite(buffer);
            else
            {
                //读出文件数据比缓冲区小，重新定义缓冲区大小，只用于读取文件的最后一个数据块
                byte[] b = new byte[leng];
                for (int i = 0; i < leng; i++)
                    b[i] = buffer[i];
                Response.BinaryWrite(b);
            }
        }
        r.Close();//关闭下载文件
        Response.End();//结束文件下载

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