ContentCachingResponseWrapper Produces Empty Response

Question

I'm trying to implement filter for logging requests and responses in Spring MVC application. I use the following code:

@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));     } } 

So, I get my request and respone logged as expected. Here are the logs:

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"} -------------------------------------- 

However, the empty response is returned. Here's the output from 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 

Any ideas?

Thanks

Answer 1

After couple of hours of struggling, I've finally found the solution.

In short, ContentCachingResponseWrapper.copyBodyToResponse() should be called in the end of the filter method.

ContentCachingResponseWrapper caches the response body by reading it from response output stream. So, the stream becomes empty. To write response back to the output stream ContentCachingResponseWrapper.copyBodyToResponse() should be used.

Answer 2

Finally solved the problem. Here is the perfect solution:

import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.ObjectMapper; import org.apache.commons.io.IOUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.http.*; import org.springframework.stereotype.Component; import org.springframework.web.filter.OncePerRequestFilter; import org.springframework.web.util.ContentCachingRequestWrapper; import org.springframework.web.util.ContentCachingResponseWrapper;  import javax.servlet.FilterChain; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.net.URI; import java.util.Enumeration; import java.util.Map;  import static java.nio.charset.StandardCharsets.UTF_8; import static net.logstash.logback.marker.Markers.appendFields;  @Component public class LoggingFilter extends OncePerRequestFilter {    private static final Logger LOGGER = LoggerFactory.getLogger(LoggingFilter.class);    @Autowired   private ObjectMapper objectMapper;    @Override   protected void doFilterInternal(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, FilterChain filterChain) throws ServletException, IOException {      ContentCachingRequestWrapper requestWrapper = new ContentCachingRequestWrapper(httpServletRequest);     ContentCachingResponseWrapper responseWrapper = new ContentCachingResponseWrapper(httpServletResponse);      filterChain.doFilter(requestWrapper, responseWrapper);      String requestUrl = requestWrapper.getRequestURL().toString();     HttpHeaders requestHeaders = new HttpHeaders();     Enumeration headerNames = requestWrapper.getHeaderNames();     while (headerNames.hasMoreElements()) {       String headerName = (String) headerNames.nextElement();       requestHeaders.add(headerName, requestWrapper.getHeader(headerName));     }     HttpMethod httpMethod = HttpMethod.valueOf(requestWrapper.getMethod());     Map<String, String[]> requestParams = requestWrapper.getParameterMap();      String requestBody = IOUtils.toString(requestWrapper.getInputStream(),UTF_8);     JsonNode requestJson = objectMapper.readTree(requestBody);      RequestEntity<JsonNode> requestEntity = new RequestEntity<>(requestJson,requestHeaders, httpMethod, URI.create(requestUrl));     LOGGER.info(appendFields(requestEntity),"Logging Http Request");       HttpStatus responseStatus = HttpStatus.valueOf(responseWrapper.getStatusCode());     HttpHeaders responseHeaders = new HttpHeaders();     for (String headerName : responseWrapper.getHeaderNames()) {       responseHeaders.add(headerName, responseWrapper.getHeader(headerName));     }     String responseBody = IOUtils.toString(responseWrapper.getContentInputStream(), UTF_8);     JsonNode responseJson = objectMapper.readTree(responseBody);     ResponseEntity<JsonNode> responseEntity = new ResponseEntity<>(responseJson,responseHeaders,responseStatus);     LOGGER.info(appendFields(responseEntity),"Logging Http Response");     responseWrapper.copyBodyToResponse();   } }