上传图片到服务器保存，并返回url

    @Value("${file.path}")
    private String dirPath;

 @ResponseBody
    @PostMapping("/upload")
    @ApiOperation(value = "文档/文件上传")
    public ApiResult<?> upload(@RequestParam("file") MultipartFile file) {
        if (file.isEmpty()) {
            return ApiResult.error("上传失败，请选择文件");
        }
        File defFileDir = new File(dirPath);
        if (!defFileDir.exists()) {
            boolean isMkSuccess = defFileDir.mkdirs();
        }

        String prefix;
        try {
            prefix = Objects.requireNonNull(file.getOriginalFilename())
                    .substring(file.getOriginalFilename().lastIndexOf("."));
        } catch (Exception e) {
            prefix = ".png";
        }
        String fileName = UUID.randomUUID() + prefix;
        String newFilePath = dirPath + File.separator + fileName;
        try {
            file.transferTo(new File(newFilePath));

            return generateUrlApiResult(fileName);
        } catch (IOException e) {
            e.printStackTrace();
            return ApiResult.error("上传失败");
        }
    }

//        ServletUriComponentsBuilder contextPath = ServletUriComponentsBuilder.fromCurrentContextPath();
//        String currentHost = contextPath.build().getHost();
//        if ("localhost".equals(currentHost)) {
//            String ipHostAddress = "";
//            try {
//                Enumeration<NetworkInterface> allNetInterfaces = NetworkInterface.getNetworkInterfaces();
//                while (allNetInterfaces.hasMoreElements()) {
//                    NetworkInterface netInterface = (NetworkInterface) allNetInterfaces.nextElement();
//                    Enumeration<InetAddress> addresses = netInterface.getInetAddresses();
//                    while (addresses.hasMoreElements()) {
//                        InetAddress ip = (InetAddress) addresses.nextElement();
//                        if (ip instanceof Inet4Address
//                                && !ip.isLoopbackAddress() //loopback地址即本机地址，IPv4的loopback范围是127.0.0.0 ~ 127.255.255.255
//                                && !ip.getHostAddress().contains(":")) {
//                            System.out.println(ip.getHostAddress());
//                            ipHostAddress = ip.getHostAddress();
//                        }
//                    }
//                }
//            } catch (Exception e) {
//                e.printStackTrace();
//            }
//            contextPath.host(ipHostAddress);
//        }
//
//        String fileDownloadUri = contextPath
//                .path(File.separator + fileName)
//                .toUriString(); 

//        HashMap<String, String> responseMap = new HashMap<>();
//        responseMap.put("url", fileDownloadUri);
 //       return ApiResult.success(responseMap);