/**
 * 下载单个文件
 *
 * @param docId
 */
 @GetMapping("/download/{docId}")
 public void download(@PathVariable("docId") String docId,
       HttpServletResponse response) {
  outWrite(response, docId);
 }
 
 /**
 * 输出文件流
 * @param response
 * @param docId
 */
 private void outWrite(HttpServletResponse response, String docId) {
  ServletOutputStream out = null;
  try {
   out = response.getOutputStream();
   // 禁止图像缓存。
   response.setHeader("Pragma", "no-cache");
   response.setHeader("Cache-Control", "no-cache");
   response.setDateHeader("Expires", 0);
   byte[] bytes = docService.downloadFileSingle(docId);
   if (bytes != null) {
    MagicMatch match = Magic.getMagicMatch(bytes);
    String mimeType = match.getMimeType();
    response.setContentType(mimeType);
    out.write(bytes);
   }
   out.flush();
  } catch (Exception e) {
   UnitedLogger.error(e);
  } finally {
   IOUtils.closeQuietly(out);
  }
 }

npm install js-file-download --save

import fileDownload from "js-file-download";

 // 文档操作列对应事件
 async handleCommand(item, data) {
  switch (item.key) {
  case "download":
   var res = await this.download(data);
   return fileDownload(res, data.name);
  ...
  default:
  }
  // 刷新当前层级的列表
  const folder = this.getLastFolderPath();
  this.listClick(folder.folderId, folder.name);
 },
 // 下载
 async download(row) {
  if (this.isFolder(row.type)) {
  return FolderAPI.download(row.id);
  } else {
  return DocAPI.download(row.id);
  }
 },

/**
 * 下载单个文件
 * @param {*} id
 */
const download = (id) => {
 return request({
 url: _DataAPI.download + id,
 method: "GET",
 responseType: 'blob'
 });
};