public void HttpDownloadFile(string url)
        {
            string strFileName = url.Substring(url.LastIndexOf("/")+1);
            // 设置参数
            HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
            //发送请求并获取相应回应数据
            HttpWebResponse response = request.GetResponse() as HttpWebResponse;
            //直到request.GetResponse()程序才开始向目标网页发送Post请求
            Stream responseStream = response.GetResponseStream();
            //创建本地文件写入流
            //string uploadPath = "/DownFile"; 
            string uploadPath = Environment.CurrentDirectory;
            uploadPath = uploadPath.Substring(0, uploadPath.IndexOf("bin")) + "DownFile\\" + strFileName;
            Stream stream = new FileStream(uploadPath, FileMode.Create);
            byte[] bArr = new byte[stream.Length];
            int size = responseStream.Read(bArr, 0, (int)bArr.Length);
            while (size > 0)
            {
                stream.Write(bArr, 0, size);
                size = responseStream.Read(bArr, 0, (int)bArr.Length);
            }
            stream.Close();
            responseStream.Close();
   //return path;
        }