Section B.4. Configuring Log4J with a Configuration File

B.4. Configuring Log4J with a Configuration File

The InitServlet uses the Log4jConfigurator to set up Log4J with our Log4J Configuration file, jbossatwork-log4j.xml. Example B-9 shows the Log4jConfigurator class.

Example B-9. Log4jConfigurator.java

 package com.jbossatwork.util; import java.net.*; import org.apache.log4j.BasicConfigurator; import org.apache.log4j.xml.DOMConfigurator; public class Log4jConfigurator {     /**      * Making the default (no arg) constructor private      * ensures that this class cannnot be instantiated.      */     private Log4jConfigurator(  ) {  }     /**      * Configures Log4J for an application using the specified Log4J XML      * configuration     file.      *      * @param log4jXmlFileName The specified Log4J XML configuration file.      */     public static void setup(String log4jXmlFileName) {         URL url = ResourceLoader.getAsUrl(log4jXmlFileName);         if (url != null) {             // An URL (from the CLASSPATH) that points to the Log4J XML             // configuration file that was provided, so use Log4J's             // DOMConfigurator with the URL to initialize Log4J with the             // contents of the Log4J XML configuration file.             DOMConfigurator.configure(url);         } else {             // An URL that points to the Log4J XML configuration file wasn't             // provided, so use Log4J's BasicConfigurator to initialize Log4J.             BasicConfigurator.configure(  );         }     } } 

The Log4jConfigurator.setup( ) method configures Log4J for the JAW Motors application. The ResourceLoader.getAsUrl( ) method retrieves the Log4J configuration file from the CLASSPATH. If the configuration file is found, the Log4jConfigurator.setup( ) method uses the Log4J DOMConfigurator.setup( ) method to configure Log4J with our Log4J configuration file. Otherwise, the Log4jConfigurator.setup( ) method uses Log4J's BasicConfigurator.configure( ) method to configure Log4J with default settings.