what is the right way to use log4j within jsp pages

Question

I mean, I want the logger name to reflect the source.jsp file, no matter if it is included in another file or compiled to a class or whatever.

Answer 1

The following is the code. All the configuration file placement and configuration are the same as how it is use in Servlet or other class.

<%@ page import="org.apache.log4j.Logger" %>

Demonstration log4j usage in jsp

<% Logger log = Logger.getLogger("com.mobilefish.demo.test"); log.debug("Show DEBUG message"); log.info("Show INFO message"); log.warn("Show WARN message"); log.error("Show ERROR message"); log.fatal("Show FATAL message"); %>

The log messages are shown in the Tomcat console and in the ${catalina.home}/logs/demo.log file.

Answer 2

You could write a factory method which takes the current request as a parameter, and which obtains a Logger based on the JSP name, something like this:

public static Logger getLogger(HttpServletRequest request) {
 String requestUri = request.getRequestURI();
 String jspName = requestUri.substring(requestUri.lastIndexOf('/'));
 return Logger.getLogger(jspName);
}

You might have to play with it a bit to make it work (I haven't tested the above code), but that's the gist of it.

This could be used directly from the JSP, or from a bean or tag class which is used by the JSP, as long as it has access to the request object.

Answer 3

Use the appropriate ConversionPattern when configuring log4j, e.g:

%d [%C] %-5p %c - %m%n

Here, the %C outputs the fully qualified class name when you call any of the Logger class methods.

Answer 4

What's wrong with:

Logger logger = Logger.getLogger( "source.jsp" );

You can prepend it with a better non-ambiguous prefix, of course. Actually, something along the lines JSPS.source.jsp is better, as you can set up logging rules for JSPS logger, that would later be applied to all sub-loggers.

Having said this, why do you need to log from JSP directly?