ASP.net下载文件

    public void FileDownload(string filePath, string fileName, string systemFileName)
    {
        FileInfo DownloadFile
                = new FileInfo(HttpContext.Current.Request.PhysicalApplicationPath + filePath + "\\" + systemFileName);
        if (DownloadFile.Exists)
        {
            Response.Clear();
            Response.ClearHeaders();
            Response.Buffer = false;
            Response.ContentType = "application/octet-stream";
            Response.AppendHeader("Content-Disposition", "attachment;filename="
                + HttpUtility.UrlDecode(fileName, System.Text.Encoding.UTF8));
            Response.AppendHeader("Content-Length", DownloadFile.Length.ToString());
            Response.WriteFile(DownloadFile.FullName);
            Response.Flush();
            Response.End();
        }
    }