Logging all API call traffic in Java servlets

Question

We have a few servlets like the one below, taking JSON request and produce JSON response. And the requirement is to log all API call traffic.

import org.slf4j.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class CommentServlet {
  private static final Logger LOG = LoggerFactory.getLogger(CommentServlet.class);
  public void postComment(HttpServletRequest request, HttpServletResponse response) throws IOException {
    String commentRequested = request.getParameter("comment");
    LOG.info(commentRequested);
    Object postResultModel = processComment(commentRequested);
    JsonUtil.writeResponse(response, postResultModel);
  }
  /**
  * doesn't reallty matter what processComment does
  */
  public Object processComment(String comment) {
    return new Object();
  }
}

import org.slf4j.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
public class JsonUtil {
    private static final Logger LOG = LoggerFactory.getLogger(JsonUtil.class);
    private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
    public static void writeResponse(HttpServletResponse response, Object modelObject) throws IOException {
        String modelJson = OBJECT_MAPPER.writeValueAsString(modelObject);
        LOG.info(modelJson);
        response.setContentType("application/json");
        response.getWriter().write(modelJson);
    }
}

if you can mainly review how the logging is done, I'd like feedback on the general approach as much as whether there's any way to improve it.

Answer 1

private static final Logger LOG = LoggerFactory.getLogger(CommentServlet.class);

This is considered as bad practice ... of course there is an argument from the other side as well.

The right thing to use should be

private final Logger LOG = LoggerFactory.getLogger(getClass()); 

This basically helps you leverage the capabilities of polymorphism and use the same logger in inherited classes with its real name.

Answer 2

IMHO, the problem is that all the responses are using the same JsonUtil logger, and each request is using the logger of each Servlet. This is making it difficult to configure meaningful appender for logs. (imagine if you want to configure "comment" feature as mentioned above to have certain log level and write to a comment.log file).