H5提交MIME类型为multipart/form-data类型的表单，后端如何处理（比如java，.NET）？

Question

<form action="example.jsp" enctype="multipart/form-data" method="POST">
    <label for="fname">请选择</label>
    <input type="file" name="fname"/>
</form>

Answer 1

/**
     * 上传图片接口，任务详情的插图和评论的插图都用
     * 
     * @param request
     * @param taskId
     * @param taskDiscussId
     * @return
     */
    @RequestMapping(value = "tasks/{taskId}/files", method = RequestMethod.POST)
    public Results<String> uploadFiles(HttpServletRequest request, @PathVariable Integer taskId,
            Integer taskDiscussId) {
        Results<String> r = new Results<String>();
        r.setCode(StatusCode.OK);
        try {
            // 上传图片处理
            CommonsMultipartResolver multipartResolver =
                    new CommonsMultipartResolver(request.getSession().getServletContext());
            if (!multipartResolver.isMultipart(request)) {
                r.setCode(StatusCode.FAIL);
                r.setMessage("没有接收到文件，请重新选择！");
                return r;
            }
            // 将请求还原成文件上传请求
            MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;
            MultipartFile mf = multipartRequest.getFile("file");

            // 验证文件后缀是否正确
            if (!FileFormatUtil.checkFileFormat(mf.getOriginalFilename(), FileFormat.IMAGE)) {
                HugeServerException.throwException("用户上传头像格式错误", StatusCode.USER_IMG_FOR_ERROR);
            }
            // 这里是上传文件，返回保存的路径
            String savePath = null;
            // 前台有传评论ID的话，那就是上传评论的插图（目前只有上传图片，无其他格式文件）
            if (taskDiscussId == null) {
                savePath = UploadFileUtils.uploadFile(request, mf, ConfigParam.task_attach);
                TaskFile file = new TaskFile();
                file.setTaskId(taskId);
                file.setFileType(FileType.IMAGE.getValue());
                file.setFileName(mf.getName());
                file.setFilePath(savePath);
                taskFileService.insert(file);
            }
            else {
                savePath = UploadFileUtils.uploadFile(request, mf, ConfigParam.task_discuss_attach);
                TaskDiscussFile file = new TaskDiscussFile();
                file.setTaskDiscussId(taskDiscussId);
                file.setFileType(FileType.IMAGE.getValue());
                file.setFileName(mf.getName());
                file.setFilePath(savePath);
                taskDiscussFileService.insert(file);
            }
            r.setData(savePath);
        }
        catch (Exception e) {
            log.error("File upload failed.", e);
            r.setCode(StatusCode.TASK_FILE_UPLOAD_FAIL);
            r.setMessage("任务文件上传失败！");
        }
        return r;
    }

public class UploadFileUtils extends BaseFile{
    
    
    public static String getNewFileName(String suffix){
        if(StringUtils.isEmpty(suffix)){
           return null;
        }
        return new Date().getTime()+UNDERLINE+(new Random().nextInt(100000000)+1)+POINT+suffix;
    }
    
    

    public static String uploadFile(HttpServletRequest request,MultipartFile file, String fileSavePath) throws Exception{
        if(file == null){
            return "";
        }
        String originalFilename = file.getOriginalFilename();
        if(StringUtils.isBlank(originalFilename)){
            return "";
        }
        //boolean isr = FileFormatUtil.checkFileFormat(originalFilename, fileFormat);
        /*if(!isr){
            throw new HugeFileException("上传文件格式错误，请重试");
        }*/
        //物理路径
        String wlPath = getFullPath(request,fileSavePath);
        File f = new File(wlPath);
        if(!f.exists()){
            f.mkdirs();
        }
        //获取后缀名
        String suffix = FileUtils.getFileSuffix(originalFilename);
        //通过后缀名，获取新的一个文件名
        String newFileName = getNewFileName(suffix);
        wlPath = wlPath+SPRIT+newFileName;
        //这个参数是为了保存到数据库中的值
        String ljPath = fileSavePath +SPRIT+newFileName;
        //保存文件
        copy(file.getInputStream(), wlPath);
        //file.transferTo(new File(f.getAbsolutePath(),newFileName));
        return ljPath;
    }
    

    private static void copy(InputStream fis, String newPath) throws Exception{  
        FileOutputStream fos =null;
        try {
            fos = new FileOutputStream(newPath);
            byte[] buffer = new byte[1024];     
            int len = 0;     
            while ((len = fis.read(buffer)) > 0) {     
                fos.write(buffer, 0, len);     
            }     
        } catch (Exception e) {
            e.printStackTrace();
            throw new Exception("保存失败");
        }finally {
             try {
                fis.close();
                fos.close(); 
             } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                throw new Exception("保存失败");
             }     
        }
       
    }
    
    
    public static String getFullPath(HttpServletRequest request,String filePath){
        return ConfigParam.path_absolute+filePath;
      //return request.getSession().getServletContext().getRealPath(fileConfig);
    }
    
}

Answer 2

问题已解决 公司里用的.NET传文件的方式是用AJAX的POST方式提交，在url后面加相关参数，Request Payload中加文件的二进制流

Answer 3

ASP.NET MVC

[HttpPost]
public ActionResult UploadImage(HttpPostedFileBase image){
    image.SaveAs(fileName);
}

ASP.NET Core

[HttpPost]
public IActionResult UploadImage(IFormFile image){
    image.Save(fileName);
}