C# 后台获取请求来源、文件下载

 HTTP请求下载文件

/// <summary>
/// Http方式下载文件
/// </summary>
/// <param name="url">url地址</param>
/// <param name="path">路径</param>
/// <param name="fileName">文件名</param>
/// <returns></returns>
public static bool HttpDownLoadold(string url, string path, string fileName)
{
     bool flag = false;
     long startPosition = 0; // 上次下载的文件起始位置
     FileStream writeStream; // 写入本地文件流对象
     // 判断文件夹是否存在
     if (Directory.Exists(path) == false)
     {
          Directory.CreateDirectory(path);
     }
     //判断文件是否存在
     if (File.Exists(fileName))
     {
         writeStream = File.OpenWrite(fileName);             // 存在则打开要下载的文件
         startPosition = writeStream.Length;                  // 获取已经下载的长度
         writeStream.Seek(startPosition, SeekOrigin.Current); // 本地文件写入位置定位
     }
     else
     {
         writeStream = new FileStream(path + fileName, FileMode.Create);// 文件不保存创建一个文件
         startPosition = 0;
     }
     try
     {
         HttpWebRequest myRequest = (HttpWebRequest)HttpWebRequest.Create(url);// 打开网络连接
         if (startPosition > 0)
         {
               myRequest.AddRange((int)startPosition);// 设置Range值,与上面的writeStream.Seek用意相同,是为了定义远程文件读取位置
         }
         Stream readStream = myRequest.GetResponse().GetResponseStream();// 向服务器请求,获得服务器的回应数据流
         byte[] btArray = new byte[512];// 定义一个字节数据,用来向readStream读取内容和向writeStream写入内容
         int contentSize = readStream.Read(btArray, 0, btArray.Length);// 向远程文件读第一次
         while (contentSize > 0)// 如果读取长度大于零则继续读
         {
               writeStream.Write(btArray, 0, contentSize);// 写入本地文件
               contentSize = readStream.Read(btArray, 0, btArray.Length);// 继续向远程文件读取
         }
         //关闭流
         writeStream.Close();
         readStream.Close();
         flag = true;        //返回true下载成功
         }
         catch (Exception)
         {
              writeStream.Close();
              flag = false;       //返回false下载失败
         }
         return flag;
 }

文件流下载文件

 void BigFileDownload()
        {
            try
            {
                string FileName = "测试.docx";
                string filePath = Page.Server.MapPath("~/Content/测试.docx");
                //以字符流的形式下载文件
                FileStream fs = new FileStream(filePath, FileMode.Open);
                byte[] bytes = new byte[(int)fs.Length];
                fs.Read(bytes, 0, bytes.Length);
                fs.Close();
                Response.ContentType = "application/octet-stream;charset=gb2321";

                //通知浏览器下载文件而不是打开;对中文名称进行编码
                Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(FileName, System.Text.Encoding.UTF8));
                Response.BinaryWrite(bytes);
            }
            catch (Exception ex)
            {

            }
            finally
            {
                Response.Flush();
                Response.End();
            }
        }

asp.net mvc 获取请求源

 /// <summary>
        /// 下载APP
        /// </summary>
        /// <returns></returns>
        [AllowAnonymous]
        [Route("download/app")]
        public ActionResult DownloadApp() {

            string android = "android";
            //获取客服端请求源
            string agent = Request.UserAgent;
            string[] keywords = { "Android", "iPhone", "iPod", "iPad", "Windows Phone", "MQQBrowser" };

            // CloudWave.Framework.Core.Logging.Logging4net.WriteInfo(agent);
            //排除 Windows 桌面系统           
            //if (!agent.Contains("Windows NT") || (agent.Contains("Windows NT") && agent.Contains("compatible; MSIE 9.0;")))
            var downloadurl = "";
            //判断是微信, 直接响应应用宝地址
            if (agent.ToLower().Contains("micromessenger")) {
                //获取配置信息
                var wxUrl = ConfigurationManager.AppSettings["YingYongBao"];
                if (!string.IsNullOrEmpty(wxUrl)) {
                    return Redirect(wxUrl);
                }
                return RedirectToAction("index");
            }
            if (agent.ToLower().Contains(android)) {
                downloadurl = ConfigurationManager.AppSettings["AndroidUrl"];
                if (string.IsNullOrEmpty(downloadurl)) {
                    return RedirectToAction("index");
                }
            } else {
                downloadurl = ConfigurationManager.AppSettings["IOSUrl"];
                if (string.IsNullOrEmpty(downloadurl)) {
                    return RedirectToAction("index");
                }
                if (agent.ToLower().Contains("weibo")) {
                    downloadurl = "itms-apps" + downloadurl.Substring(downloadurl.IndexOf(":")); //itms-apps://
                }
            }
            return Redirect(downloadurl);
        }