客户端:

public class SendFile {
    public static void main(String[] args) {
        RestTemplate restTemplate = new RestTemplate();

        SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory();
        requestFactory.setBufferRequestBody(false);
        restTemplate.setRequestFactory(requestFactory);

        File file = new File("D:\software\test.txt");
        File file2 = new File("D:\software\test2.txt");

        MultiValueMap<String,Object> parts = new LinkedMultiValueMap<>();
        try {
            parts.add("files", new MultipartFileResource(new FileInputStream(file),"test"));
            parts.add("files", new MultipartFileResource(new FileInputStream(file2),"text2"));

        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.MULTIPART_FORM_DATA);
        HttpEntity<MultiValueMap<String,Object>> request = new HttpEntity<>(parts, headers);
        ResponseEntity<String> ret =restTemplate.exchange("http://localhost:8886/file/reciveFile", HttpMethod.POST, request, String.class);
       System.out.println(ret.getBody().toString());
    }

public class MultipartFileResource extends InputStreamResource {
    //命名没错哦  就是这个名字
    private String filename;

    public MultipartFileResource(InputStream inputStream, String filename) {
        super(inputStream);
        this.filename = filename;
    }

    //这个必须写
    @Override
    public String getFilename() {
        return this.filename;
    }
    //这个必须写
    @Override
    public long contentLength() throws IOException {
        // we do not want to generally read the whole stream into memory ...
        return -1;
    }
}

服务器:

@RequestMapping(value="/file/reciveFile",method=RequestMethod.POST)
    public Result reciveFile(List<MultipartFile> files) throws IOException {
        //获取文件名
        files.get(0).getName();
        //获取输入流
        files.get(0).getInputStream();
        //获取长度
        files.get(0).getInputStream().available();
        return null;
    }

备注:

fileResource那个类，必须重写getFilename和contentLength，变量名就是filename