upload 文件自动上传写法，前后端下载流文件流

<el-uploadv-model:file-list="fileList":action="app.api+'/student/student/import'":headers="{//   'Content-Type': 'multipart/form-data;boundary=----split-boundary', 此处切记不要加，否则会造成后端报错  Required request part 'file' is not present 'token':token}"name="file"//此处默认为fileclass="upload-demo"@on-success="handleSuccess":on-error="handleAvatarSuccess":limit="3":on-progress="beforeAvatarUpload">
<!--:auto-upload="false"--><!--          :http-request="replaceRes"--><span v-if="jinDu"><el-progress style="width: 245px; height: 19px" :text-inside="true" :stroke-width="20":percentage="percentage"/></span><span v-if="isUpload" style="color: #59c2c7;cursor:pointer;"@click="uploadChangeValue">导入学生学籍信息</span><template #tip><span style="color: #ff8282; margin-left: 20px">{{ importText }}</span></template></el-upload>
<script lang="ts" setup>//此处后端穿了一个流给前端，所以需要解析一下，然后赋值给一个按钮，在点击时候才下载！！！
const handleSuccess = (response: any) => {console.log(response)if (Object.values(response.headers)[0] == 'application/vnd.ms-excel;charset=UTF-8') {const url = window.URL.createObjectURL(new Blob([response.data]));// 创建a标签，并隐藏a标签let link = document.createElement('a')link.style.display = 'none'// a标签的href属性指定下载链接link.href = url//setAttribute() 方法添加指定的属性，并为其赋指定的值// 后缀格式.csv/.xsls要和需要和后端返回格式相同，这里以.csv为例link.setAttribute('download', '文件名称.xlsx')document.body.appendChild(link)link.click()document.body.removeChild(link)}
};//此处用于实时监听进度条进度
const beforeAvatarUpload = (event: any) => {let loadProgress = Math.floor(event.percent); //这就是当前上传的进度//可以进行其他逻辑percentage.value = loadProgress;importText.value = "学籍信息导入中……";if (percentage.value == 100) {importText.value = "学籍导入成功！"}
};
</script>

    @PostMapping("import")@ApiOperation("导入")@RequiresPermissions("student:student:import")@ApiImplicitParam(name = "file", value = "文件", paramType = "query", dataType = "file")public void importExcel(@RequestParam("file") MultipartFile file, HttpServletResponse response) throws Exception {UserDetail userDetail = SecurityUser.getUser();//保存所有的表单信息、如果表达有错误、将返回给客户端if (userWithErrorListInMap == null) {userWithErrorListInMap = new HashMap<>();}//每次都清空数据userWithErrorListInMap.put(userDetail.getId(), new ArrayList<>());ZsRef<Boolean> hasError = new ZsRef<>();new ExcelServiceListener<StudentExcel, StudentEntity>(studentService, file.getInputStream()) {private List<RegionEntity> regionList;/*** 地区编码 去掉末尾的数字0, 用于判断权限*/private String userRegionCodeForPermission;private SchoolEntity schoolForPermission;@Overridepublic void invoke(StudentExcel data, AnalysisContext context) {if (regionList == null) {regionList = regionService.selectList(new HashMap<>());}if (userDetail.getRegionCode() != null) {//去掉地区编码后面的0userRegionCodeForPermission = userDetail.getRegionCode().replaceAll("0+?$", "");}if (userDetail.getSchoolCode() != null) {schoolForPermission = schoolService.selectByParams("schoolCode", userDetail.getSchoolCode());}// 校验姓名if (data.getName() == null) {hasError.value = true;data.setName(data.getName() + "##名字不能为空, 长度最多四汉字");}// 校验性别if (data.getGender() == 2) {hasError.value = true;data.setGenderStr(data.getGenderStr() + "##性别只能是（男、女）中的一个");}// 校验身份证号if (isEmpty(data.getIdCard()) || data.getIdCard().length() != 18) {hasError.value = true;data.setName(data.getName() + "##身份证长度18位");}if (isEmpty(data.getNation())) {hasError.value = true;data.setNation(data.getNation() + "##民族不能为空");}// ************************ 校验地区 *********************************// 判断地区表中是否包含含这一项RegionEntity region1 = null, region2 = null;for (RegionEntity item : regionList) {if (data.getRegion1() != null && data.getRegion1().contains(item.getName())) {region1 = item;}if (data.getRegion2() != null && data.getRegion2().contains(item.getName())) {region2 = item;}}// RegionEntity region = regionList.stream().filter(r -> r.getName().contains(data.getRegion())).findFirst().orElse(null);if (region1 == null) {hasError.value = true;data.setRegion1(data.getRegion1() + "##城市不存在");}if (region2 == null) {if (data.getRegion1().contains("济源")) {//济源没有区县} else {hasError.value = true;data.setRegion2(data.getRegion2() + "##区县不存在");}}if (region1 != null && region2 != null) {data.setRegionCode(region2.getCode());//判断地区和学校 是否具备权限if (isNotEmpty(userDetail.getRegionCode())) {if (String.valueOf(data.getRegionCode()).startsWith(userRegionCodeForPermission)) {//具备权限} else {hasError.value = true;data.setRegion2(data.getRegion2() + "##不具备该地区的权限");}}}//判断是否具备该学校的权限if (isNotEmpty(userDetail.getSchoolCode())) {if (isEquals(schoolForPermission.getName(), data.getSchoolName())) {//具备权限} else {hasError.value = true;data.setSchoolName(data.getSchoolName() + "##不具备该学校的权限");}} else {//不需要判断学校权限}if (isEquals(hasError.value, true)) {userWithErrorListInMap.get(userDetail.getId()).add(data);} else {//没有错误的才添加super.list.add(data);}}@Overridepublic void doAfterAllAnalysed(AnalysisContext context) {if (isEquals(hasError.value, true)) {//  有错误, 不入库} else {studentService.saveStudentWidthSchoolAndClass(super.list);}}}.start(2);if (Objects.equals(hasError.value, true)) {String errorFileName = file.getOriginalFilename().replace(".xlsx", "错误提示.xlsx");export(response, errorFileName, userWithErrorListInMap.get(userDetail.getId()));} else {PrintWriter pw = response.getWriter();//逻辑删除导入学籍时学籍不存在的学校班级（当前学期）schoolService.deleteBySchoolCode();gradeClassService.deleteByClassCode();//恢复导入学籍时学籍存在但逻辑删除的学校班级（当前学期）schoolService.updateBySchoolCode();gradeClassService.updateByClassCode();pw.write(ZsJson.toJson(new Result<>()));pw.close();}System.out.println("excel解析完成");}

下载一个后端返回的流文件

注意跨域问题

后端解决跨域问题

const downLoadExport=()=>{axios({method: 'post',url: baseUrl+"/electric/electricassets/download/assets",headers: {"Content-Type": "application/json;charset=UTF-8","token":getToken()},responseType: 'blob'}).then(response => {if (Object.values(response.headers)[0]=='application/vnd.ms-excel;charset=UTF-8'){const url = window.URL.createObjectURL(new Blob([response.data]));// 创建a标签，并隐藏a标签let link = document.createElement('a')link.style.display = 'none'// a标签的href属性指定下载链接link.href = url//setAttribute() 方法添加指定的属性，并为其赋指定的值// 后缀格式.csv/.xsls要和需要和后端返回格式相同，这里以.csv为例link.setAttribute('download',   '文件名称.xlsx')document.body.appendChild(link)link.click()document.body.removeChild(link)}})
}