Class LogFactory

java.lang.Object
org.apache.juli.logging.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).

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.

  • Method Summary

    Modifier and Type
    Method
    Description
    static LogFactory
    getFactory()
    Return the singleton LogFactory instance.
    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 the log handlers that the JULI LogManager has associated with the given class loader, so a stopped application no longer keeps its log files open.

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Method Details

    • 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

      Return the singleton LogFactory instance. The Log implementation is discovered once, using a ServiceLoader lookup for providers of the Log interface, falling back to DirectJDKLog if no suitable provider is found. Providers that cannot be loaded or that do not expose a public constructor taking the log name as its only argument are ignored.

      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 the log handlers that the JULI LogManager has associated with the given class loader, so a stopped application no longer keeps its log files open. If the class loader has no logging configuration yet, one is briefly created for it and released again. This is a NO-OP when the standard java.util.logging.LogManager implementation is in use: that one has a single global configuration and resetting it would discard the logging of the whole JVM. The JULI log manager associates its configuration with the current thread's context class loader, so the given class loader is made current for the duration of the reset.
      Parameters:
      classLoader - ClassLoader for which to release the LogFactory. Must not be null.