故事的开始

老板说：系统很慢，下载半个小时无法下载，是否考虑先压缩再给用户下载？

                     

 

　　本来是已经压缩过了，不过第一反应应该是用户下的数量多，导致压缩包很大，然后自己测试发现，只是等待的时间比较久而已，仍然是下载状态中，并不是系统慢，但是用户体验肯定是最直观的，确实是我们做得不够好，单纯弹出遮罩层显示冰冷的“拼命加载中……”，对用户来说确实不够友好。嗯，了解实际情况了，那就开撸，增加用户体验。

 解决它

效果图：

 

 

Vue+ElementUI

 <el-progress v-if="dlProgress>0" :text-inside="true" :stroke-width="18" :percentage="dlProgress" status="success" style="margin-bottom:10px"></el-progress>

Axios

downloadTask(index,row) {
      let own =this;
      this.fullscreenLoading = true;
      this.axios({
        method: 'post',
        url: this.baseUrl + '/api/Task/DownLoad',
        data: {id: row.id},
        responseType: 'blob',
　　　　 //敲黑板
        onDownloadProgress (progress) {
          own.dlProgress=Math.round(progress.loaded / progress.total * 100);
        }
      })
      .then((res) => {
        this.fullscreenLoading = false;
        let fileName = decodeURI(res.headers["content-disposition"].split("=")[1]);
        let url = window.URL.createObjectURL(new Blob([res.data]));
        let link = document.createElement('a');
        link.style.display = 'none';
        link.href = url;
        link.setAttribute('download', fileName);
        document.body.appendChild(link);
        link.click();
　　　　 document.body.removeChild(link);　
        this.$message.success('下载成功');
      })
      .catch(() => {
        this.fullscreenLoading = false;
      });
    },

下载：

 protected IActionResult DownLoad(string fullFilePath)
        {
            var fileName = Path.GetFileName(fullFilePath);
            HttpContext.Response.Headers.Append("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(fileName));

            var contentType = Common.Helper.FileHelper.GetContentType(fileName);
            var stream = new FileStream(fullFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
            return File(stream, contentType);
        }

        protected IActionResult DownLoad(VDownloadByte download)
        {
            if (string.IsNullOrEmpty(download.fileName))
                return new JsonResult(ShowError("生成文件失败"));
            var fileName = Path.GetFileName(download.fileName);
            HttpContext.Response.Headers.Append("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(fileName)); 
            var contentType = Common.Helper.FileHelper.GetContentType(fileName); 
            return File(download.fileByte, contentType);
        }

        protected IActionResult DownLoad(VDownloadStream download)
        {
            if (string.IsNullOrEmpty(download.fileName))
                return new JsonResult(ShowError("生成文件失败"));
            var fileName = Path.GetFileName(download.fileName);
            HttpContext.Response.Headers.Append("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(fileName));
            var contentType = Common.Helper.FileHelper.GetContentType(fileName);
            return File(download.Stream, contentType);
        }

分片下载：

        /// <summary>
        /// 手动分片下载
        /// </summary>
        protected async Task<IActionResult> DownLoadBlock(string fullFilePath)
        {
            var fileName = Path.GetFileName(fullFilePath);
            int bufferSize = 1024;
            Response.ContentType = FileHelper.GetContentType(fileName); 
            Response.Headers.Append("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(fileName));

            using (FileStream fs = new FileStream(fullFilePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
            {
                using (Response.Body)
                {
                    long contentLength = fs.Length;
                    Response.ContentLength = contentLength;

                    byte[] buffer;
                    long hasRead = 0;

                    while (hasRead < contentLength)
                    {
                        if (HttpContext.RequestAborted.IsCancellationRequested)
                        {
                            break;
                        }

                        buffer = new byte[bufferSize];
                        int currentRead = fs.Read(buffer, 0, bufferSize);
                        await Response.Body.WriteAsync(buffer, 0, currentRead);
                        await Response.Body.FlushAsync();
                        hasRead += currentRead;
                    }
                }
            }

            return new EmptyResult();
        }