Package org.apache.felix.framework

Class Logger

  • All Implemented Interfaces:
    java.util.EventListener, ServiceListener
    public class Logger
extends java.lang.Object
implements ServiceListener

    This class mimics the standard OSGi LogService interface. An instance of this class is used by the framework for all logging. By default this class logs messages to standard out. The log level can be set to control the amount of logging performed, where a higher number results in more logging. A log level of zero turns off logging completely.

    The log levels match those specified in the OSGi Log Service (i.e., 1 = error, 2 = warning, 3 = information, and 4 = debug). The default value is 1.

    This class also uses the System Bundle's context to track log services and will use the highest ranking log service, if present, as a back end instead of printing to standard out. The class uses reflection to invoking the log service's method to avoid a dependency on the log interface.

    • Constructor Detail

      • Logger

        public Logger()

    • Method Detail

      • setLogLevel

        public final void setLogLevel​(int i)

      • getLogLevel

        public final int getLogLevel()

      • setSystemBundleContext

        protected void setSystemBundleContext​(BundleContext context)

      • log

        public final void log​(int level,
                      java.lang.String msg)

      • log

        public final void log​(int level,
                      java.lang.String msg,
                      java.lang.Throwable throwable)

      • log

        public final void log​(ServiceReference sr,
                      int level,
                      java.lang.String msg)

      • log

        public final void log​(ServiceReference sr,
                      int level,
                      java.lang.String msg,
                      java.lang.Throwable throwable)

      • log

        public final void log​(Bundle bundle,
                      int level,
                      java.lang.String msg)

      • log

        public final void log​(Bundle bundle,
                      int level,
                      java.lang.String msg,
                      java.lang.Throwable throwable)

      • doLog

        protected void doLog​(Bundle bundle,
                     ServiceReference sr,
                     int level,
                     java.lang.String msg,
                     java.lang.Throwable throwable)

      • _log

        private void _log​(Bundle bundle,
                  ServiceReference sr,
                  int level,
                  java.lang.String msg,
                  java.lang.Throwable throwable)

      • _logReflectively

        private void _logReflectively​(java.lang.Object[] logger,
                              ServiceReference sr,
                              int level,
                              java.lang.String msg,
                              java.lang.Throwable throwable)

      • startListeningForLogService

        private void startListeningForLogService()
        This method is called when the system bundle context is set; it simply adds a service listener so that the system bundle can track log services to be used as the back end of the logging mechanism. It also attempts to get an existing log service, if present, but in general there will never be a log service present since the system bundle is started before every other bundle.

      • serviceChanged

        public final void serviceChanged​(ServiceEvent event)
        This method implements the callback for the ServiceListener interface. It is public as a byproduct of implementing the interface and should not be called directly. This method tracks run-time changes to log service availability. If the log service being used by the framework's logging mechanism goes away, then this will try to find an alternative. If a higher ranking log service is registered, then this will switch to the higher ranking log service.
        Specified by:
        serviceChanged in interface ServiceListener
        Parameters:
        event - The ServiceEvent object.

      • setLogger

        private void setLogger​(java.lang.Object logObj)
        This method sets the new log service object. It also caches the method to invoke. The service object and method are stored in array to optimistically eliminate the need to locking when logging.