.net中 登录 才能下载文件的方法 Response.WriteFile实现下载

protected void Button2_Click(object sender, EventArgs e)  

        {  
　　　　　　　　//可以在这里加是否登录的判断

            string fileName = "chracater14.jpg";//客户端保存的文件名 （其他文件格式都支持）

            string filePath = Server.MapPath("../../images/chracater14.jpg");//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();  

        }