Java Logging: show the source line number of the c

Question

The numerous (sigh...) logging frameworks for Java all do a nice job of showing the line number of the source file name for the method that created the log message:

log.info("hey");

 [INFO] [Foo:413] hey

But if have a helper method in between, the actual caller will be the helper method, and that is not too informative.

log_info("hey");

[INFO] [LoggingSupport:123] hey

Is there a way to tell the logging system to remove one frame from the callstack when figuring out the source location to print?

I suppose that this is implementation specific; what I need is Log4J via Commons Logging, but I am interested to hear about other options.

Answer 1

For Log4j2 the answer is provided completely by the use of logger wrappers as described in the Log4j2 manual under Example Usage of a Generated Logger Wrapper. One can simply generate (using the org.apache.logging.log4j.core.tools.Generate$ExtendedLogger tools illustrated there) a logger wrapper with a single STUB level, and then adapt that to create custom logging methods mimicking the use of the logIfEnabled(FQCN, LEVEL, Marker, message, Throwable) - possibly ignoring the STUB level and using the regular ones - then if desired, deleting or commenting out the STUB level and its methods). For this purpose the FormattedMessage can be helpful.

The source line, while expensive, can then be easily shown as part of the full location information by using the %l location conversion pattern element in the PatternLayout given in the configuration, or more specifically using the %L line number and/or the %M method conversion.

Now with complete example at: Java Logging: Log4j Version2.x: show the method of an end-client caller (not an intermediate logging helper method)

Answer 2

This isn't possible out of the box. The best you can do in this case is to create the logger in the caller and pass it to the util method. This way, you can at least get an idea where the call has come from.