获取文件流及下载

1、当你知道文件地址，想获取文件流的时候：

 var stream = await HttpClientFactory.Create().GetStreamAsync(fileUrl).ConfigureAwait(false);

2、如果是发送http请求，获取文件，接口返回流，那么按照下面的方式获取流：

　　　　public HttpResponseMessage MakeThePager()
        {
            try
            {
               
                Stream stream = ZuJuanServiceApi.CreatePaperStream(schoolPhaseId, subjectId, paperXml,extension);

                HttpResponseMessage message = new HttpResponseMessage();
                message.Content = new StreamContent(stream);
                message.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
                message.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
                {
                    FileName = Guid.NewGuid().ToString().Replace("-", "") + "." + extension
                };
                return message;
            }
            catch (Exception ex)
            {
                Logging.LogHelper.Logger.Error(ex.Message, ex);
                return new HttpResponseMessage(System.Net.HttpStatusCode.NotFound);
            }
        }

　　　　public static async Task<Stream> GetAsync(string uri, object param)
        {
            string requestUri = FormatUri(uri, param);
            using (HttpClient httpClient = HttpClientFactory.Create())
            {
                SetAuthentication(httpClient);
                httpClient.BaseAddress = new Uri(BaseUri);
                var result = await httpClient.GetAsync(requestUri).ConfigureAwait(false);
                var streamContent = result.Content as StreamContent;
                return  await streamContent.ReadAsStreamAsync();
            }
        }

　

3、获取文件流之后，接下来该下载了

        public async Task<ActionResult> DownLoadAsync(string resourceJson, string albumName, string connId)
        {
            string directoryPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "TempFile");//存放临时文件的路径
            if (!Directory.Exists(directoryPath))
                Directory.CreateDirectory(directoryPath);
            var zipPath = Path.Combine(directoryPath, Guid.NewGuid().ToString() + ".zip"); //生成一个新的唯一的路径
                Stream zipStream = await XyyZipHelper.CompressAsync(streamDict, zipPath).ConfigureAwait(false);
                DownLoadHelper.Update(connId, true);
                if (Request.UserAgent.ToUpper().Contains("FIREFOX"))
                {
                    return File(zipStream, "application/x-zip-compressed", string.Concat("\"", albumName, "\".zip"));
                }
                else
                {
                    return File(zipStream, "application/x-zip-compressed", string.Concat(albumName, ".zip"));
                }

        }

　　

4、下载Excel常用方式

public ActionResult DownLoad()
　　　　{
            var fileName = CountyModel.CountyName + "教职工" + "——" + Tools.DataType.ExcelTitle(dataType) + "表" + Currentuser.UserId + "_" + tempUserIdStr + ".xls";
            string path = "/DownLoad/" + fileName;
            if (!Directory.Exists(Request.MapPath("/DownLoad")))
            {
                System.IO.Directory.CreateDirectory(Request.MapPath("/DownLoad"));
            }
            using (FileStream file = new FileStream(Server.MapPath(path), FileMode.OpenOrCreate, FileAccess.ReadWrite))
            {
                wk.Write(file);//工作簿的数据写入文件
                file.Close();
                //下载
                FileStream fs = new FileStream(Server.MapPath(path), FileMode.Open);//重新获取文件流
                byte[] bytes = new byte[(int)fs.Length];
                fs.Read(bytes, 0, bytes.Length);
                fs.Close();
                Response.ContentType = "application/octet-stream";
                //通知浏览器下载文件而不是打开
                SetExcelDownLoadHeader(path);
                Response.BinaryWrite(bytes);
                Response.Flush();
                Response.End();
            }
            //删除临时文件
            if (System.IO.File.Exists(Server.MapPath(path)))
            {
                //如果存在则删除
                System.IO.File.Delete(Server.MapPath(path));
            }
　　　　 }

        protected void SetExcelDownLoadHeader(string path)
        {
            String agent = Request.Headers.Get("USER-AGENT");
            if (agent != null && agent.IndexOf("Firefox") > -1)
            {// FF
                Response.AddHeader("Content-Disposition", "attachment;  filename=" + System.IO.Path.GetFileName(Server.MapPath(path)));
            }
            else
            {
                Response.AddHeader("Content-Disposition", "attachment;  filename=" + HttpUtility.UrlEncode(System.IO.Path.GetFileName(Server.MapPath(path)), System.Text.Encoding.UTF8));
            }
        }