HttpServlet：提取输入请求json和输出响应json

Question

我有一个通过http公开的RESTFul服务。它期望一个POST请求的Json输入。请指导我如何从HttpServletRequest和HttpServletResponse对象中提取Json输入。问题很复杂，因为我正在使用spring HandlerInterceptorAdapter，而且我无法访问输入参数和输出。

我的拦截器代码如下：

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.json.simple.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

public class MyInterceptor extends HandlerInterceptorAdapter {

  static final Logger logger = LoggerFactory.getLogger(RequestResponseInterceptor.class);

  //before the actual handler will be executed
  public boolean preHandle(HttpServletRequest request,
                           HttpServletResponse response, Object handler)
      throws Exception {

    logRequestPayload(request);

    return true;
  }

  private void logRequestPayload(HttpServletRequest request) {
    JSONObject requestObj = new JSONObject(request.getParameterMap());
    logger.debug("request:" + requestObj);
  }

  //after the handler is executed
  public void postHandle(
      HttpServletRequest request, HttpServletResponse response,
      Object handler, ModelAndView modelAndView)
      throws Exception {

    logResponsePayload(response);

  }

  private void logResponsePayload(HttpServletResponse response) {
    JSONObject responseObj = extractJsonFromResponse(response);
    logger.debug("response:" + response);
  }

  private JSONObject extractJsonFromResponse(HttpServletResponse response) {
    return new JSONObject();
  }
}

由于