文件上载Java Spring

Question

我正在尝试用Java以块形式上载文件。
我的块上载功能：

@Async
private Future<String> sendChunk(byte[] chunk, int start, int end, int numberOfChunks, String name, String sessionId) throws IOException {

    LinkedMultiValueMap<String, Object> requestParams = new LinkedMultiValueMap<>();
    requestParams.add("data", new String(java.util.Base64.getEncoder().encode(chunk), "UTF-8"));
    requestParams.add("start", start);
    requestParams.add("end", end);
    requestParams.add("numberOfChunks", numberOfChunks);
    requestParams.add("fileName", name);
    requestParams.add("session", sessionId);

    HttpEntity<LinkedMultiValueMap<String, Object>> requestEntity = new HttpEntity<>(requestParams);
    UploadResponse uploadResponse = restTemplate.exchange(fileServiceUrl, HttpMethod.POST, requestEntity, new ParameterizedTypeReference<UploadResponse>(){}).getBody();
    return new AsyncResult<>(uploadResponse.getSessionId());
}

这就是文件服务API的外观：

@RequestMapping(value = "/simpleUploader", method = RequestMethod.POST, produces = "application/json")
public ResponseEntity<UploadResponse> simpleUploader(
    @RequestParam("data") String data,
    @RequestParam("session") String sessionId,
    @RequestParam("start") int start,
    @RequestParam("end") int end,
    @RequestParam("numberOfChunks") int numberOfChunks,
    @RequestParam("fileName") String fileName) throws IOException {
    ....
}

Answer 1

我的代码遇到的唯一问题是，当我第一次调用文件服务API时，“sessionid”将为null。
当我将映射项的值设置为null时，整个项不会被传递。我不知道这一点。
我的修复方法是将defaultvalue添加到@requestparam（“session”）String sessionid中，以便方法声明如下所示：

@RequestMapping(value = "/simpleUploader", method = RequestMethod.POST, produces = "application/json")
public ResponseEntity<UploadResponse> simpleUploader(
    ...
    @RequestParam(value = "session", defaultValue = "") String sessionId,
    ... ) throws IOException {
    ....
}