Kajol1106 / Log4j

Log4j :

1. Logging : getting messages from application (Production server) like success, errors, warnings,..etc

2. Moniter the process, find bugs from realtime environment.

3. Tools : Log4J 2.x, Java Logging, Commons Logging ..etc

4. Log Messages can be stored at different places ex., Files, Database, Email , Console..etc

5. Components

   1. Logger : (which classes) it is a base object in Log4J. It enables/activates Logging/Moniter of a class/process.

      class EmployeeController {
         Logger log = LogManager.getLogger(EmployeeController.class);
      }
      

   • Do not create Logger object for Entity/DTO/POJO classes.

   • Recomanded Controllers/Services..etc

   • Priority Methods :

     • These are pre-defined methods exist in Logger object which prints messages based on type.

     • TRACE : To find messages from multiple stages/env/apps.

     • DEBUG : To print final result of a process/ internal details

     • INFO : Current Step

     • WARN : App related messages

     • ERROR : To give details about exception

     • FATAL : Environment related issues ex:Database Connection is closed.

       TRACE > DEBUG > INFO > WARN > ERROR > FATAL

   2. Appender:- Location of messages to be stored. (classes). (where to store) Do not create Logger object for Entity/DTO/POJO classes.

      • FileAppender : Write data to Log File (___.log)

      • ConsoleAppender : Prints data at console

      • JDBCAppender : Store messages at Database table

      • SMTPAppender : Write messages to Email.

      • Project can have even multiple appenders.

   3. Layout: (how to print) Message Format/Pattern.

      • Default Layout (Message and NextLine)
      • HTML Layout (___.html)
      • XML Layout (___.xml)
      • PatternLayout (Your own format)