Chapter 2. Enabling JBoss Logging for your application

Procedure

1. Depending on your application code, use one of the following approaches:

   1. Create an instance of org.jboss.logging.Logger and initialize it by calling the static method Logger.getLogger(Class) for each class:

      src/main/java/org/acme/ExampleResource.java

      import org.jboss.logging.Logger; 

      1

      
      
      import javax.ws.rs.GET;
      import javax.ws.rs.Path;
      import javax.ws.rs.Produces;
      import javax.ws.rs.core.MediaType;
      
      @Path("/hello")
      public class ExampleResource {
      
          private static final Logger LOG = Logger.getLogger(ExampleResource.class); 

      2

      
      
          @GET
          @Produces(MediaType.TEXT_PLAIN)
          public String hello() {
              LOG.info("Hello"); 

      3

      
              return "hello";
          }
      }

      1

      Add the org.jboss.logging.Logger import statement for each class namespace that you want to use.

      2

      Add reference to the logger singleton for each class.

      3

      Set a logging level for the log message.

   2. Inject a configured org.jboss.logging.Logger instance in your beans and resource classes:

      src/main/java/org/acme/ExampleResource.java

      import javax.inject.Inject;
      import javax.ws.rs.GET;
      import javax.ws.rs.Path;
      import javax.ws.rs.Produces;
      import javax.ws.rs.core.MediaType;
      
      import org.jboss.logging.Logger; 

      1

      
      
      import io.quarkus.arc.log.LoggerName;
      
      @Path("/hello")
      public class ExampleResource {
      
          @Inject
          Logger log; 

      2

      
      
          @LoggerName("foo")
          Logger fooLog; 

      3

      
      
          @GET
          @Produces(MediaType.TEXT_PLAIN)
          public String hello() {
              log.info("Simple!");
              fooLog.info("Goes to foo logger!");
              return "hello";
          }
      }

      1

      Add the org.jboss.logging.Logger import statement for each class namespace that you want to use.

      2

      The fully qualified class name of the declaring class is used as the logger name, which is equivalent to the initialization statement org.jboss.logging.Logger.getLogger(ExampleResource.class).

      3

      Set a name for the logger. In this example, the logger name is foo, which is equivalent to the initialization statement org.jboss.logging.Logger.getLogger("foo").

      Note

      The logger instances are cached internally. A logger, that you inject into a bean, is shared for all bean instances to avoid the possible performance penalty associated with logger instantiation.

2. (Optional) Configure the logging output in your application.properties file:

   src/main/resources/application.properties

   <configuration_key>=<value>

   For example, you can create a log file and print the output to a console and to the file:

   src/main/resources/application.properties

   quarkus.log.file.enable=true
   quarkus.log.file.path=/tmp/trace.log

3. Run your application in development mode:

   ./mvnw quarkus:dev

4. Navigate to http://localhost:8080/hello.

5. Depending on your configuration, review the log messages on your terminal or in your log file.

   Example output for the ExampleResource.class with logging level set to INFO:

   2021-05-21 15:38:39,751 INFO  [io.quarkus] (Quarkus Main Thread) my-project my-version on JVM (powered by Quarkus 1.13.3.Final) started in 1.189s. Listening on: http://localhost:8080
   2021-05-21 15:38:39,765 INFO  [io.quarkus] (Quarkus Main Thread) Profile dev activated. Live Coding activated.
   2021-05-21 15:38:39,766 INFO  [io.quarkus] (Quarkus Main Thread) Installed features: [cdi, resteasy]
   2021-05-21 15:38:58,790 INFO  [ExampleResource] (executor-thread-1) Hello