.Net Core WebAPI + Axios +Vue 实现下载与下载进度条

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：

分片下载

    public static class HttpContextExtension
    {
        /// <summary>
        /// 获取客户Ip
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public static string GetClientUserIp(this HttpContext context)
        {
            var ip = "";
            if (context.Request.Headers.ContainsKey("X-Forwarded-For"))
            {
                ip = context.Request.Headers["X-Forwarded-For"].ToString();
            }
            if (string.IsNullOrEmpty(ip) && context.Request.Headers.ContainsKey("X-Real-IP"))
            {
                ip = context.Request.Headers["X-Real-IP"].ToString();
            }
            if (string.IsNullOrEmpty(ip))
            {
                ip = context.Connection.RemoteIpAddress.MapToIPv4().ToString();
            }
            if (string.IsNullOrEmpty(ip))
                return ip;
            var sp = ip.RemoveSpacing().Split(',');
            return sp[0];
        }

        /// <summary>
        /// 通过文件流下载文件
        /// </summary>
        /// <param name="context"></param>
        /// <param name="filePath">文件完整路径</param>
        /// <param name="contentType">访问这里 https://tool.oschina.net/commons </param>
        public static void DownLoadFile(this HttpContext context,string filePath, string contentType= "application/octet-stream")
        {
            var fileName = Path.GetFileName(filePath);

            int bufferSize = 1024; 
            context.Response.ContentType = contentType;
            context.Response.Headers.Append("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(fileName));
            context.Response.Headers.Append("Charset", "utf-8");
            context.Response.Headers.Append("Access-Control-Expose-Headers", "Content-Disposition");
            //context.Response.Headers.Append("Access-Control-Allow-Origin", "*");
            //使用FileStream开始循环读取要下载文件的内容
            using (FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read))
            {
                using (context.Response.Body) 
                {
                    long contentLength = fs.Length; 
                    context.Response.ContentLength = contentLength;

                    byte[] buffer;
                    long hasRead = 0;  
                    while (hasRead < contentLength)
                    {
                        if (context.RequestAborted.IsCancellationRequested)
                        {
                            break;
                        }

                        buffer = new byte[bufferSize];
                        //从下载文件中读取bufferSize(1024字节)大小的内容到服务器内存中
                        int currentRead = fs.Read(buffer, 0, bufferSize);
                        context.Response.Body.Write(buffer, 0, currentRead);
                        context.Response.Body.Flush();
                        hasRead += currentRead;
                    }
                    context.Response.Body.Close();
                }
                fs.Close();
            }
        }

        /// <summary>
        /// 通过文件流下载文件
        /// </summary>
        /// <param name="context"></param>
        /// <param name="filePath">文件完整路径</param>
        /// <param name="contentType">访问这里 https://tool.oschina.net/commons </param>
        public static void DownLoadFile(this HttpContext context,string fileName, byte[] fileByte, string contentType = "application/octet-stream")
        {
            int bufferSize = 1024;
            
            context.Response.ContentType = contentType;
            context.Response.Headers.Append("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(fileName));
            context.Response.Headers.Append("Charset", "utf-8");
            context.Response.Headers.Append("Access-Control-Expose-Headers", "Content-Disposition");
         
            //context.Response.Headers.Append("Access-Control-Allow-Origin", "*");
            //使用FileStream开始循环读取要下载文件的内容
            using (Stream fs = new MemoryStream(fileByte))
            {
                using (context.Response.Body)
                {
                    long contentLength = fs.Length;
                    context.Response.ContentLength = contentLength;

                    byte[] buffer;
                    long hasRead = 0;
                    while (hasRead < contentLength)
                    {
                        if (context.RequestAborted.IsCancellationRequested)
                        {
                            break;
                        }
                        
                        buffer = new byte[bufferSize];
                        //从下载文件中读取bufferSize(1024字节)大小的内容到服务器内存中
                        int currentRead = fs.Read(buffer, 0, bufferSize);
                        context.Response.Body.Write(buffer, 0, currentRead);
                        context.Response.Body.Flush();
                        hasRead += currentRead;
                    }
                }
            }
        }
    }

完美~