下载文件是在带有IIS的Chrome浏览器中直接打开文件,而不是下载文件

protected void btnDownloadFile_Click(object sender, EventArgs e)
{
    string fileFullPath = @"E:\AllFiles\History\John's certificate.doc";
    FileInfo fileInfo = new FileInfo(fileFullPath);
    if (fileInfo.Exists)
    {
        Response.Clear();
        Response.ClearHeaders();
        Response.ClearContent();

        Response.AddHeader("Content-Disposition", "attachment; filename=\"" + fileInfo.Name + "\"");
        Response.AddHeader("Content-Length", fileInfo.Length.ToString());

        Response.ContentType = MIMETypeHelper.GetMimeType(fileInfo.Extension); // This method supplies the contenttype based on file extention for example if .doc extension returns application/msword

        Response.Flush();
        Response.TransmitFile(fileInfo.FullName);
        Response.End();
    }
}