5.2.3. Add Logging to an Application with JBoss Logging

To log messages from your application you create a Logger object (org.jboss.logging.Logger) and call the appropriate methods of that object. This task describes the steps required to add support for this to your application.

Prerequisites

You must meet the following conditions before continuing with this task:
  • If you are using Maven as your build system, the project must already be configured to include the JBoss Maven Repository. Refer to Section 2.3.2, “Configure the JBoss EAP 6 Maven Repository Using the Maven Settings”
  • The JBoss Logging JAR files must be in the build path for your application. How you do this depends on whether you build your application using JBoss Developer Studio or with Maven.
    • When building using JBoss Developer Studio this can be done selecting Project -> Properties from the JBoss Developer Studio menu, selecting Targeted Runtimes and ensuring the runtime for JBoss EAP 6 is checked.
    • When building using Maven this can be done by adding the following dependency configuration to your project's pom.xml file.
      <dependency>
         <groupId>org.jboss.logging</groupId>
         <artifactId>jboss-logging</artifactId>
         <version>3.1.2.GA-redhat-1</version>
         <scope>provided</scope>
      </dependency>
      
    You do not need to include the JARs in your built application because JBoss EAP 6 provides them to deployed applications.
Once your project is setup correctly. You need to follow the following steps for each class that you want to add logging to:
  1. Add imports

    Add the import statements for the JBoss Logging class namespaces that you will be using. At a minimum you will need to import import org.jboss.logging.Logger.
    import org.jboss.logging.Logger;
    
  2. Create a Logger object

    Create an instance of org.jboss.logging.Logger and initialize it by calling the static method Logger.getLogger(Class). Red Hat recommends creating this as a single instance variable for each class.
    private static final Logger LOGGER = Logger.getLogger(HelloWorld.class);
    
  3. Add logging messages

    Add calls to the methods of the Logger object to your code where you want it to send log messages. The Logger object has many different methods with different parameters for different types of messages. The easiest to use are:
    debug(Object message)
    info(Object message)
    error(Object message)
    trace(Object message)
    fatal(Object message)
    These methods send a log message with the corresponding log level and the message parameter as a string.
    LOGGER.error("Configuration file not found.");
    
    For the complete list of JBoss Logging methods refer to the org.jboss.logging package in the JBoss EAP 6 API Documentation.

Example 5.1. Using JBoss Logging when opening a properties file

This example shows an extract of code from a class that loads customized configuration for an application from a properties file. If the specified file is not found, a ERROR level log message is recorded.
import org.jboss.logging.Logger;
public class LocalSystemConfig
{
   private static final Logger LOGGER = Logger.getLogger(LocalSystemConfig.class);

   public Properties openCustomProperties(String configname) throws CustomConfigFileNotFoundException
   {
      Properties props = new Properties();
      try 
      {
         LOGGER.info("Loading custom configuration from "+configname);
         props.load(new FileInputStream(configname));
      }
      catch(IOException e) //catch exception in case properties file does not exist
      {
         LOGGER.error("Custom configuration file ("+configname+") not found. Using defaults.");
         throw new CustomConfigFileNotFoundException(configname);
      }
      
      return props;
   }