Class LogFactory


  • public class LogFactory
    extends Object
    This is a modified LogFactory that uses a simple ServiceLoader based discovery mechanism with a default of using JDK based logging. An implementation that uses the full Commons Logging discovery mechanism is available as part of the Tomcat extras download. Why? It is an attempt to strike a balance between simpler code (no discovery) and providing flexibility - particularly for those projects that embed Tomcat or some of Tomcat's components - is an alternative logging implementation is desired. Note that this implementation is not just a wrapper around JDK logging (like the original commons-logging impl). It adds 2 features - a simpler configuration (which is in fact a subset of log4j.properties) and a formatter that is less ugly. The removal of 'abstract' preserves binary backward compatibility. It is possible to preserve the abstract - and introduce another (hardcoded) factory - but I see no benefit. Since this class is not intended to be extended - all protected methods are removed. This can be changed - but again, there is little value in keeping dead code. Just take a quick look at the removed code ( and it's complexity). -------------- Original comment:

    Factory for creating Log instances, with discovery and configuration features similar to that employed by standard Java APIs such as JAXP.

    IMPLEMENTATION NOTE - This implementation is heavily based on the SAXParserFactory and DocumentBuilderFactory implementations (corresponding to the JAXP pluggability APIs) found in Apache Xerces.

    Author:
    Craig R. McClanahan, Costin Manolache, Richard A. Sitze
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static LogFactory getFactory()
      Construct (if necessary) and return a LogFactory instance, using the following ordered lookup procedure to determine the name of the implementation class to be loaded.
      Log getInstance​(Class<?> clazz)
      Convenience method to derive a name from the specified class and call getInstance(String) with it.
      Log getInstance​(String name)
      Construct (if necessary) and return a Log instance, using the factory's current set of configuration attributes.
      static Log getLog​(Class<?> clazz)
      Convenience method to return a named logger, without the application having to care about factories.
      static Log getLog​(String name)
      Convenience method to return a named logger, without the application having to care about factories.
      static void release​(ClassLoader classLoader)
      Release any internal references to previously created LogFactory instances that have been associated with the specified class loader (if any), after calling the instance method release() on each of them.
    • Method Detail

      • getInstance

        public Log getInstance​(String name)
                        throws LogConfigurationException

        Construct (if necessary) and return a Log instance, using the factory's current set of configuration attributes.

        NOTE - Depending upon the implementation of the LogFactory you are using, the Log instance you are returned may or may not be local to the current application, and may or may not be returned again on a subsequent call with the same name argument.

        Parameters:
        name - Logical name of the Log instance to be returned (the meaning of this name is only known to the underlying logging implementation that is being wrapped)
        Returns:
        A log instance with the requested name
        Throws:
        LogConfigurationException - if a suitable Log instance cannot be returned
      • getInstance

        public Log getInstance​(Class<?> clazz)
                        throws LogConfigurationException
        Convenience method to derive a name from the specified class and call getInstance(String) with it.
        Parameters:
        clazz - Class for which a suitable Log name will be derived
        Returns:
        A log instance with a name of clazz.getName()
        Throws:
        LogConfigurationException - if a suitable Log instance cannot be returned
      • getFactory

        public static LogFactory getFactory()
                                     throws LogConfigurationException

        Construct (if necessary) and return a LogFactory instance, using the following ordered lookup procedure to determine the name of the implementation class to be loaded.

        • The org.apache.commons.logging.LogFactory system property.
        • The JDK 1.3 Service Discovery mechanism
        • Use the properties file commons-logging.properties file, if found in the class path of this class. The configuration file is in standard java.util.Properties format and contains the fully qualified name of the implementation class with the key being the system property defined above.
        • Fall back to a default implementation class (org.apache.commons.logging.impl.LogFactoryImpl).

        NOTE - If the properties file method of identifying the LogFactory implementation class is utilized, all of the properties defined in this file will be set as configuration attributes on the corresponding LogFactory instance.

        Returns:
        The singleton LogFactory instance
        Throws:
        LogConfigurationException - if the implementation class is not available or cannot be instantiated.
      • getLog

        public static Log getLog​(Class<?> clazz)
                          throws LogConfigurationException
        Convenience method to return a named logger, without the application having to care about factories.
        Parameters:
        clazz - Class from which a log name will be derived
        Returns:
        A log instance with a name of clazz.getName()
        Throws:
        LogConfigurationException - if a suitable Log instance cannot be returned
      • getLog

        public static Log getLog​(String name)
                          throws LogConfigurationException
        Convenience method to return a named logger, without the application having to care about factories.
        Parameters:
        name - Logical name of the Log instance to be returned (the meaning of this name is only known to the underlying logging implementation that is being wrapped)
        Returns:
        A log instance with the requested name
        Throws:
        LogConfigurationException - if a suitable Log instance cannot be returned
      • release

        public static void release​(ClassLoader classLoader)
        Release any internal references to previously created LogFactory instances that have been associated with the specified class loader (if any), after calling the instance method release() on each of them.
        Parameters:
        classLoader - ClassLoader for which to release the LogFactory