Chapter 9: Using the Apache Log Tag Library - BeKnowledge

Chapter 9: Using the Apache Log Tag Library
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n
log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=logtags.log
log4j.appender.R.MaxFileSize=100KB
# Keep one backup file
log4j.appender.R.MaxBackupIndex=2
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n
With these settings in place, execute the JSP presented in Listing 9-8. This JSP includes a TRACE-level
message.
Listing 9-8: SimpleLogTrace.jsp
Test Log Tag Library
Trace level message.
You should see output in the debug logs now.
Executing this JSP will produce the following message with the TRACE level in the Web server
console:
TRACE [Thread-11] (LoggerTag.java:109) - Trace level message.
Conclusion
Page 10 of 11
In this chapter, we discussed a newly released tag library, Log, from Apache, for using log4j within a
JSP to perform logging. This solves the age-old problem of having controlled logging from within a
JSP. By changing the configuration, it is possible to redirect logging information to any preferred
destination in any desired format. But careful consideration is required before you include in your Web
application CPU-intensive logging operations such as writing logging data to a database, as it might
affect the performance of that application.
This brings us to the end of the log4j discussion. All the topics explained in Chapters 5 through 9 should
help you understand the internals of log4j and how to use it in practical applications. The smaller
examples provided should enable you to grasp the concepts presented and see quick results to better
understand the use of log4j. The more extensive examples should help you to correlate the use of log4j
file://C:\Documents and Settings\deepak\Local Settings\Temp\~hh572B.htm
6/14/2010