Log4J

Main steps

1. If necessary, review presentation: Log4J

2. Add dependency on log4j in pom.xml file:

       <dependencies>
       ...
           <dependency>
               <groupId>org.apache.logging.log4j</groupId>
               <artifactId>log4j-core</artifactId>
               <version>2.23.1</version>
           </dependency>
           <dependency>
               <groupId>org.apache.logging.log4j</groupId>
               <artifactId>log4j-api</artifactId>
               <version>2.23.1</version>
           </dependency>
       ...
       </dependencies>

   where ... are some other existing settings

3. Recompile project and regenerate settings for eclipse:

   mvn clean compile eclipse:eclipse

4. Add file logger named file with file appender and layout format into configuration file src/main/resources/log4j2.properties:

   appender.file.type = File
   appender.file.name = file
   appender.file.fileName = logs/test.log
   appender.file.layout.type = PatternLayout
   appender.file.layout.pattern = %d{yyyy-MM-dd HH:mm:ss} %-5p %c{4} %M:%L - %m%n

5. Add entry for log appender to file:

   rootLogger.appenderRef.file.ref = file

6. Add log level entries for activity:

   logger.jtm.name = jtm.extra05.Log
   logger.jtm.level = info
   logger.jtm.additivity = false
   logger.jtm.appenderRefs = file, stdout
   logger.jtm.appenderRef.file.ref = file
   logger.jtm.appenderRef.stdout.ref = stdout
   
   logger.jtmExt.name = jtm.extra05.Log.ExtLog
   logger.jtmExt.level = trace
   logger.jtmExt.additivity = false
   logger.jtmExt.appenderRefs = file, stdout
   logger.jtmExt.appenderRef.file.ref = file
   logger.jtmExt.appenderRef.stdout.ref = stdout
7. Review package jtm.extra05

8. Declare and initialize class logger in Log class:

   private static final Logger log = LogManager.getLogger(Log.class);
9. Implement static methods to log trace, debug, info, warn, error, fatal which will write log messages with appropriate level, using the class logger.
10. Implement method getLogger() which returns reference to used logger

11. In nested class ExtLog declare and initialize logger:

    static final Logger log = LogManager.getLogger(ExtLog.class);
12. In internal class ExtLog implement static methods trace, debug, info, warn, error, fatal which will write log messages with appropriate level.
13. Check that unit tests are passing