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The Log4E logging plug-in

The Log4E logging plug-in. David Gallardo. What is logging good for?. Tracing program execution during development Debugging Providing an audit trail for a program Recording soft-errors (lost connections, etc.) for monitoring performance and troubleshooting

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The Log4E logging plug-in

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  1. The Log4E logging plug-in David Gallardo

  2. What is logging good for? • Tracing program execution during development • Debugging • Providing an audit trail for a program • Recording soft-errors (lost connections, etc.) for monitoring performance and troubleshooting • A logging framework lets you use different logging levels • You can turn different types of messages on and off • You can send different types of messages to different destinations

  3. Adding logging code • Replaces System.out.println() calls throughout • Don’t need to be removed • Like adding System.out.println() calls, it’s somewhat tedious to add logging code • Utility of logging code is improved if it’s consistent—logs can be searched with scripts, for example

  4. The Log4E plug-in • Provides wizards that automate the addition of logging code • Add import and declaration for logger • Insert logging at start and end of methods • Insert logging of variables and method parameters

  5. What Log4E doesn’t do • Log4E does not provide a logging framework • Doesn’t configure your framework • Doesn’t make a fresh pot of coffee

  6. Choosing a logging framework • Log4E supports three logging frameworks: • Log4J • Java 1.4 Logging • Jakarta Commons Logging • Log4J is the original logging framework that Java 1.4 logging is modeled after • Jakarta Commons Logging is actually a wrapper for logging frameworks • We’ll use Log4J in this example because it’s mature, well-documented and supported, and easier to configure

  7. Installing Log4J • Download a zip or compressed tarfile from: Apache.org website • Uncompress to a local directory • In your Eclipse project’s properties • Locate Java Build Path • On Libraries page, click on Add External Jars • Browse for your Log4J directory, and locate the log4J Jar file in the /dist/lib directory • Press Open, followed by OK

  8. Create a Log4J configuration file • The easiest way to configure Log4J is to add a log4j.properties file to your source directory. • There are many options available which we won’t cover here, but essentially you need to define: • A logger • An appender • A pattern layout • The following example uses the default root logger, appends to the console and prints the date, time, message priority, thread and message

  9. A sample log4j.properties file # Logger log4j.rootLogger=DEBUG, ConApp # Appender log4j.appender.ConApp=org.apache.log4j.ConsoleAppender # PatternLayout log4j.appender.ConApp.layout=org.apache.log4j.PatternLayout log4j.appender.ConApp.layout.ConversionPattern=%d [%t] %-5p %c - %m%n

  10. Demo • Create a simple Java application • Ensure log4j is on class path • Use Log4E to add several types of logging messages • Run program

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