Jakarta Commons Cookbook

7.12. Obtaining Apache Log4J

Problem

You need to use Apache Log4J to print statements to a log file for informational or debugging purposes.

Solution

Download Apache Log4J 1.2.8 from the Binary Downloads page (http://logging.apache.org/site/binindex.cgi) of the Apache Logging Services project. On this page you will find two links to Jakarta-log4j-1.2.8.tar.gz and Jakarta-log4j-1.2.8.zip. Once this archive is uncompressed, you will find a log4j-1.2.8.jar file in the dist/lib directory. Put this JAR file in your classpath and you will be ready to use Log4J in your application.

Discussion

Log4J (formerly known as Jakarta Log4J) is a highly configurable logging framework providing hierarchical loggers, various log destinations, and log formats. Messages are written to Log4J Logger objects, which represent a specific category in a hierarchy of log categories; for example, the com.discursive.Blah category is a child of the com.discursive category. All messages sent to a child category are sent to each ancestor in a tree of Logger categories. A category can be assigned an Appender and a Layout; an Appender controls where a message is sent, and a Layout defines the formatting and contents of a message. Log4J ships with a number of Appender implementations, including SMTPAppender, RollingFileAppender, SocketAppender, SyslogAppender, and NTEventLogAppender. Log4J also ships with a number of Layout implementations, including XMLLayout, PatternLayout, HTMLLayout, and DateLayout.

See Also

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