log4j: Change format of loggers configured in another library.

Question

Using clojure, I've been able to successfully setup log4j very simply by using this log4j.properties file, and including log4j in my classpath.

# BEGIN log4j.properties

log4j.appender.STDOUT=org.apache.log4j.ConsoleAppender
log4j.appender.STDOUT.layout=org.apache.log4j.PatternLayout
log4j.appender.STDOUT.layout.ConversionPattern=%d{MMdd HHmmss SSS} %5p %c [%t] %m\n

log4j.rootLogger=DEBUG, STDOUT

Then after :use'ing clojure.contrib.logging, I'm able to print a statement with the desired formatting as expected like so:

(info "About to print this")
(debug "This is debug-level")

My question is how to achieve a consistent formatting for logging statements made from loggers configured in other libraries. I thought I could find existing loggers using org.apache.log4j.LogManager.getCurrentLoggers() and change the PatternLayouts there, but I'm not able to iterate over that enumeration in clojure, as I get the following error:

Dont know how to create ISeq from: java.util.Vector$1

I assume this is possible somehow, and probably very simply. How?

Thanks much.

Answer 1

Use enumeration-seq instead of seq:

(enumeration-seq (org.apache.log4j.LogManager/getCurrentLoggers))

For the curious, org.apache.log4j.LogManager.getCurrentLoggers() returns a java.util.Enumeration; seq doesn't know how to operate on that, but enumeration-seq does.

A simpler case not involving logging:

(seq (.elements (java.util.Vector. [1 2 3]))
; => throws an exception

(enumeration-seq (.elements (java.util.Vector. [1 2 3])))
; => returns (1 2 3)