spring mvc 透傳

隨著公司的規模及項目的增多，會有一種透明傳輸的需求，而透明傳輸的這一層就用來做許可權控制，灰度發佈，流量統計。

實現透傳需要註意的幾點：

1.Spring MVC實現url通配，後端服務的url各式各樣，並不能按照你所設想的長度，so，通配符能解決這個問題。

@RequestMapping(value = "/{serviceName}/{methodName}/**/", method = RequestMethod.GET, produces = {"application/json;charset=UTF-8"})
  public @ResponseBody Object getHttp(@PathVariable(value = "serviceName") String serviceName,
      @PathVariable(value = "methodName") String methodName, HttpServletRequest request,
      HttpServletResponse response) throws ServiceException {
    try {
      return sendGetHttp(serviceName, methodName, request, response);
    } catch (ServiceException e) {
      LOGGER.error("getHttp_service", e);
      response.setStatus(520);
      return ResponseEntity.fail(e.getErrorCode(), e.getErrorMessage());
    } catch (SystemException e) {
      LOGGER.error("getHttp_system", e);
      response.setStatus(520);
      return ResponseEntity.error(e.getErrorMessage());
    } catch (Exception e) {
      LOGGER.error("getHttp_exception", e);
      response.setStatus(520);
      return ResponseEntity.error(e.getMessage());
    }
  }

2.body流解析，POST／PUT／PATCH，一般都是包含body的請求，但是作為透明傳輸層，就是有那麼一個不包含body，所以透明傳輸的請求不適合加上@RequestBody，這時body的信息，我們可以通過HttpServletRequest解析出來。

  // request中解析出body
  private String resolveRequestToBody(HttpServletRequest request) throws IOException {
    int length = request.getContentLength();
    String requestStr = null;
    if (length != 0) {
      InputStream inputStream = request.getInputStream();
      byte b[] = new byte[length];
      inputStream.read(b);
      inputStream.close();
      requestStr = new String(b);
      LOGGER.info("requestLength:" + length + ",requestType:" + request.getContentType() + ",body:"
          + requestStr);
    }
    return requestStr;
  }

附：

通配符詳解推薦一篇博客：http://www.codeweblog.com/springmvc%E7%AC%94%E8%AE%B0%E7%B3%BB%E5%88%97-5-requestmapping%E8%AF%B7%E6%B1%82value%E7%9A%84%E9%80%9A%E9%85%8D%E7%AC%A6%E8%AF%A6%E8%A7%A3/