const content = ‘后台返回的二进制文件’;
         const blob = new Blob([content]);
         let url = window.URL.createObjectURL(blob);
         let link = document.createElement("a");
         link.style.display = "none";
         link.href = url;
         link.setAttribute(
           "download",
           res.headers["content-disposition"].split("=")[1]
         document.body.appendChild(link);
         link.click();