LCDAppender

This module is a log4j appender. Its purpose is to send log4j logging information to LCD devices (liquid crystal displays) accessible through LCDproc servers. The appender is specified in the log4j configuration file and can be assigned to one or more categories. Naturally, more than one such appender can be specified.

Download

The code consists of a single Java source file. I have put it in a jar file (LCDAppender.jar, Version 0.1) that also contains some Javadoc documentation and the compiled class file.

Using LCDAppender

It is sufficient to download the above jar file and make this available somewhere in your classpath when running your program or server. The jar file is not required when compiling your program, as log4j appenders are loaded dynamically during execution of the program only.
The enclosed Javadoc file contains a sample log4j configuration file as well as a list of the available configuration settings.
The ant script for compilation of the module is trivial. It is included.

Compatibility

LCDAppender has been developed with version log4j 1.2.7 and LCDproc version 0.4.3. It has not been tested well yet. Actually, I do not know how it behaves in long-running environments. You have been warned. Furthermore, it is not clear what happens when using more than one appender with one LCDproc server concurrently (let me know when you find out...)

Caveats

As soon as the TCP/IP connection is closed the screen simply disappears. It is thus a good idea to log anything that goes to this appender to some place that is more reliable, too.
When using the LCDAppender, log4j must be shut down properly. Otherwise, the thread created by LCDAppender will prevent the JVM from exiting. Use LogManager.shutdown(); before System.exit()-ing from your program.

Copyright

This code has been written by me, Matthias Gärtner. I place it under the same license as log4j so you can use it freely.