ContentCachingResponseWrapper产生空响应

Question

我正在尝试实现过滤器，以记录Spring MVC应用程序中的请求和响应。我使用以下代码：

@Component
public class LoggingFilter extends OncePerRequestFilter {

    private static final Logger LOGGER = LoggerFactory.getLogger(LoggingFilter.class);

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {

        ContentCachingRequestWrapper requestWrapper = new ContentCachingRequestWrapper(request);
        ContentCachingResponseWrapper responseWrapper = new ContentCachingResponseWrapper(response);

        LOGGER.debug(REQUEST_MESSAGE_FORMAT, requestWrapper.getRequestURI(), requestWrapper.getMethod(), requestWrapper.getContentType(),
                new ServletServerHttpRequest(requestWrapper).getHeaders(), IOUtils.toString(requestWrapper.getInputStream(), UTF_8));

        filterChain.doFilter(requestWrapper, responseWrapper);

        LOGGER.debug(RESPONSE_MESSAGE_FORMAT, responseWrapper.getStatus(), responseWrapper.getContentType(),
                new ServletServerHttpResponse(responseWrapper).getHeaders(), IOUtils.toString(responseWrapper.getContentInputStream(), UTF_8));
    }
}

因此，我收到了我的请求，并按预期方式记录了响应。以下是日志：

2016-10-08 19:10:11.212 DEBUG 11072 --- [qtp108982313-19] by.kolodyuk.logging.LoggingFilter
----------------------------
ID: 1
URI: /resources/1
Http-Method: GET
Content-Type: null
Headers: {User-Agent=[curl/7.41.0], Accept=[*/*], Host=[localhost:9015]}
Body: 
--------------------------------------
2016-10-08 19:10:11.277 DEBUG 11072 --- [qtp108982313-19] by.kolodyuk.logging.LoggingFilter
----------------------------
ID: 1
Response-Code: 200
Content-Type: application/json;charset=UTF-8
Headers: {}
Body: {"id":"1"}
--------------------------------------

但是，返回空响应。这是来自的输出curl：

$ curl http://localhost:9015/resources/1 --verbose
*   Trying ::1...
* Connected to localhost (::1) port 9015 (#0)
> GET /resources/1 HTTP/1.1
> User-Agent: curl/7.41.0
> Host: localhost:9015
> Accept: */*
>
< HTTP/1.1 200 OK
< Date: Sat, 08 Oct 2016 17:10:11 GMT
< Content-Type: application/json;charset=UTF-8
< Content-Length: 0
<
* Connection #0 to host localhost left intact

有任何想法吗？

谢谢

Answer 1

经过几个小时的努力，我终于找到了解决方案。

简而言之，ContentCachingResponseWrapper.copyBodyToResponse()应该在过滤方法的最后调用。

ContentCachingResponseWrapper通过从响应输出流中读取响应主体来缓存响应主体。因此，流变为空。ContentCachingResponseWrapper.copyBodyToResponse()应当将响应写回到输出流。