![]() nyOnMatch = Boolean.valueOf(denyOnMatch).booleanValue() Public void setDenyOnMatch(String denyOnMatch) ![]() * denyOnMatch "true" if you do not want log messages that match the False if you only want messages that match to be * Set this to "true" if you do not want log messages that match the given * true if the log message should not be logged if a match is found. * Returns true if the log message should not be logged if a match is found. Public void setValueToMatch(String valueToMatch) Public void setKeyToMatch(String keyToMatch) & valueToMatch.equals(event.getMDC(keyToMatch))) If (keyToMatch != null & valueToMatch != null Public class Log4JMDCFilter extends Filter * Log4J filter that stops certain log messages from being logged, based on a I only want to use the MDC for filtering, so I extended .Filter with the following class: /** Matthew's solution doesn't fit my situation because it requires you to add the MDC to the actual log output. Specifically, we have a health check call that is hit much more frequently than typical user usage and it was filling the logs unnecessarily. My need was to hide logging messages in certain cases. Matthew Farwell's answer (use MDC) is the one that worked for me and he mentions writing your own filter. ![]() If you wanted a more complex filter, you can extend it yourself, and look at the values in the MDC yourself. The code was similar to the following: public class LoggingFilter implements Filter void doFilter(ServletRequest request, ServletResponse response,įilterChain chain) throws IOException, ServletException outputs the value of MDC.get(key) in an MDC. We wanted to trace what a particular user was doing (retrospectively), so we added the user name and session id to the NDC, and then we could post filter on those. If you're using slf4j, you can even create separate log files depending upon the information in your MDC.įor instance, we did this when users logged into a website. So you would define the user name to be in the NDC and then you can change the log4j.properties to change the logging level for specific users.Īn MDC uses a Map, whereas an NDC is based upon a stack principle. An NDC/MDC allows you to insert data into your session that can be filtered by log4j. You want to look at Nested Diagnostic Contexts or Mapped Diagnostic Contexts in log4j or slf4j. In other words, in the example above, how can I set the value of usernameFilter, other than hard-coding it. The difficulty is dynamically altering the condition that sets the log level. tLevel(usernameFilter.equals(username) ? Level.TRACE : Level.INFO) String username = request.getParameter("username") For example Logger logger = Logger.getLogger("foo") ![]() I can easily add conditions to my log statements. Since I don't know beforehand which users will be affected, I cannot simply temporarily hard-code usernames. Is there a way with log4j to be able to log conditionally? In other words, I would like to be able to get trace logs only when specific users make a request. I'd like to turn on trace level logging, but since we are dealing with 100s of requests per second trace logging every single request is out of the question. The web application on which I am working occasionally develops data integrity issues for some of the users.
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