后台需要添加请求头

response.setContentType("application/octet-stream");
response.setCharacterEncoding("UTF-8");
response.setHeader("Access-Control-Expose-Headers","Content-Disposition");
response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(fileName,"utf-8") + ".xls");

前端下载代码

一定要设置responseType: 'blob'这个配置

this.$http.get('schSettlement/exportSettlementSituation',{responseType: 'blob'}).then((res) => {
                    if (!res) {
                        this.$message.error("下载模板文件失败");
                        return false;
                    }
                    const blob = new Blob([res.data], {type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet;charset=utf-8'});
                    const downloadElement = document.createElement('a');
                    const href = window.URL.createObjectURL(blob);
                    let contentDisposition = res.headers['content-disposition'];  //从response的headers中获取filename, 后端response.setHeader("Content-disposition", "attachment; filename=xxxx.docx") 设置的文件名;
                    let patt = new RegExp("filename=([^;]+\\.[^\\.;]+);*");
                    let result = patt.exec(contentDisposition);
                    let filename = decodeURI(result[1]);
                    downloadElement.style.display = 'none';
                    downloadElement.href = href;
                    downloadElement.download = filename ; //下载后文件名
                    document.body.appendChild(downloadElement);
                    downloadElement.click(); //点击下载
                    document.body.removeChild(downloadElement); //下载完成移除元素
                    window.URL.revokeObjectURL(href); //释放掉blob对象
                })