经过几个小时的努力，我终于找到了解决办法。
简言之，应该在filter方法的最后调用ContentCachingResponseWrapper.copyBodyToResponse()。
ContentCachingResponseWrapper通过从响应输出流中阅读响应体来缓存响应体。因此，流变为空。要将响应写回输出流，应使用ContentCachingResponseWrapper.copyBodyToResponse()。

终于解决了这个问题。这里是完美的解决方案：

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();
  }
}

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我喜欢使用的模式是将其分为2个过滤器：一个用于提取原始主体，另一个用于记录日志。感觉更SRP。

@Slf4j        // Lombok logging
@Component    // Spring loads filter into its filter chain
@Order(1)     // Best if this goes first (or early in filter chain)
public class CachingBodyFilter implements Filter {
    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) {
        ContentCachingRequestWrapper reqWrapper = new ContentCachingRequestWrapper((HttpServletRequest) req);
        ContentCachingResponseWrapper resWrapper = new ContentCachingResponseWrapper((HttpServletResponse) res);
        try {
            chain.doFilter(reqWrapper, resWrapper);
            resWrapper.copyBodyToResponse();  // Necessary (see answer by StasKolodyuk above)
        } catch (IOException | ServletException e) {
            log.error("Error extracting body", e);
        }
    }
}

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然后我们创建另一个过滤器来完成日志记录部分：

@Slf4j
@Component
@Order(2)     // This needs to come after `CachingBodyFilter`
public class PayloadLogFilter implements Filter {
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        chain.doFilter(req, res);
        if (req instanceof ContentCachingRequestWrapper) {
            ContentCachingRequestWrapper reqWrapper = (ContentCachingRequestWrapper) req;
            String payload = new String (reqWrapper.getContentAsByteArray(), "UTF-8");
            log.debug("Request [ {} ] has payload [ {} ]", reqWrapper.getRequestURI(), payload);
        }
    }
}

型
将它们分开的一个好处是其他类（例如Spring AOP拦截器或Spring控制器）也可以访问/使用HTTP主体。