Package org.apache.commons.logging

Class LogFactory

java.lang.Object
org.apache.commons.logging.LogFactory
Direct Known Subclasses:
SLF4JLogFactory
public abstract class LogFactory extends Object

Factory for creating Log instances, which always delegates to an instance of SLF4JLogFactory.

Author:
Craig R. McClanahan, Costin Manolache, Richard A. Sitze, Ceki Gülcü

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final String
    DIAGNOSTICS_DEST_PROPERTY
    The name (org.apache.commons.logging.diagnostics.dest) of the property used to enable internal commons-logging diagnostic output, in order to get information on what logging implementations are being discovered, what classloaders they are loaded through, etc.
    protected static Hashtable
    factories
    The previously constructed LogFactory instances, keyed by the ClassLoader with which it was created.
    static final String
    FACTORY_DEFAULT
    The fully qualified class name of the fallback LogFactory implementation class to use, if no other can be found.
    static final String
    FACTORY_PROPERTIES
    The name of the properties file to search for.
    static final String
    FACTORY_PROPERTY
    The name of the property used to identify the LogFactory implementation class name.
    static final String
    HASHTABLE_IMPLEMENTATION_PROPERTY
    Setting this system property value allows the Hashtable used to store classloaders to be substituted by an alternative implementation.
    protected static LogFactory
    nullClassLoaderFactory
    This property is not used but preserved here for compatibility.
    static final String
    PRIORITY_KEY
    The name (priority) of the key in the config file used to specify the priority of that particular config file.
    protected static final String
    SERVICE_ID
    JDK1.3+ 'Service Provider' specification.
    static final String
    TCCL_KEY
    The name (use_tccl) of the key in the config file used to specify whether logging classes should be loaded via the thread context class loader (TCCL), or not.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    LogFactory()
    Protected constructor that is not available for public use.

  • Method Summary

    Modifier and Type
    Method
    Description
    protected static Object
    createFactory(String factoryClass, ClassLoader classLoader)
    This method exists to ensure signature compatibility.
    protected static ClassLoader
    directGetContextClassLoader()
    This method exists to ensure signature compatibility.
    abstract Object
    getAttribute(String name)
    Return the configuration attribute with the specified name (if any), or null if there is no such attribute.
    abstract String[]
    getAttributeNames()
    Return an array containing the names of all currently defined configuration attributes.
    protected static ClassLoader
    getClassLoader(Class clazz)
    This method exists to ensure signature compatibility.
    protected static ClassLoader
    getContextClassLoader()
    This method exists to ensure signature compatibility.
    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.
    abstract Log
    getInstance(Class clazz)
    Convenience method to derive a name from the specified class and call getInstance(String) with it.
    abstract 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.
    protected static boolean
    isDiagnosticsEnabled()
    This method exists to ensure signature compatibility.
    protected static void
    logRawDiagnostic(String msg)
    This method exists to ensure signature compatibility.
    protected static LogFactory
    newFactory(String factoryClass, ClassLoader classLoader)
    This method exists to ensure signature compatibility.
    protected static LogFactory
    newFactory(String factoryClass, ClassLoader classLoader, ClassLoader contextClassLoader)
    This method exists to ensure signature compatibility.
    static String
    objectId(Object o)
    Returns a string that uniquely identifies the specified object, including its class.
    abstract void
    release()
    Release any internal references to previously created Loginstances returned by this factory.
    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.
    static void
    releaseAll()
    Release any internal references to previously created LogFactory instances, after calling the instance method release() on each of them.
    abstract void
    removeAttribute(String name)
    Remove any configuration attribute associated with the specified name.
    abstract void
    setAttribute(String name, Object value)
    Set the configuration attribute with the specified name.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • PRIORITY_KEY

      public static final String PRIORITY_KEY
      The name (priority) of the key in the config file used to specify the priority of that particular config file. The associated value is a floating-point number; higher values take priority over lower values.

      This property is not used but preserved here for compatibility.

      See Also:

    • TCCL_KEY

      public static final String TCCL_KEY
      The name (use_tccl) of the key in the config file used to specify whether logging classes should be loaded via the thread context class loader (TCCL), or not. By default, the TCCL is used.

      This property is not used but preserved here for compatibility.

      See Also:

    • FACTORY_PROPERTY

      public static final String FACTORY_PROPERTY
      The name of the property used to identify the LogFactory implementation class name.

      This property is not used but preserved here for compatibility.

      See Also:

    • FACTORY_DEFAULT

      public static final String FACTORY_DEFAULT
      The fully qualified class name of the fallback LogFactory implementation class to use, if no other can be found.

      This property is not used but preserved here for compatibility.

      See Also:

    • FACTORY_PROPERTIES

      public static final String FACTORY_PROPERTIES
      The name of the properties file to search for.

      This property is not used but preserved here for compatibility.

      See Also:

    • SERVICE_ID

      protected static final String SERVICE_ID
      JDK1.3+ 'Service Provider' specification.

      This property is not used but preserved here for compatibility.

      See Also:

    • DIAGNOSTICS_DEST_PROPERTY

      public static final String DIAGNOSTICS_DEST_PROPERTY
      The name (org.apache.commons.logging.diagnostics.dest) of the property used to enable internal commons-logging diagnostic output, in order to get information on what logging implementations are being discovered, what classloaders they are loaded through, etc.

      This property is not used but preserved here for compatibility.

      See Also:

    • HASHTABLE_IMPLEMENTATION_PROPERTY

      public static final String HASHTABLE_IMPLEMENTATION_PROPERTY

      Setting this system property value allows the Hashtable used to store classloaders to be substituted by an alternative implementation.

      This property is not used but preserved here for compatibility.

      See Also:

    • factories

      protected static Hashtable factories
      The previously constructed LogFactory instances, keyed by the ClassLoader with which it was created.

      This property is not used but preserved here for compatibility.

    • nullClassLoaderFactory

      protected static LogFactory nullClassLoaderFactory

      This property is not used but preserved here for compatibility.

  • Constructor Details

    • LogFactory

      protected LogFactory()
      Protected constructor that is not available for public use.

  • Method Details

    • getAttribute

      public abstract Object getAttribute(String name)
      Return the configuration attribute with the specified name (if any), or null if there is no such attribute.
      Parameters:
      name - Name of the attribute to return
      Returns:
      configuration attribute

    • getAttributeNames

      public abstract String[] getAttributeNames()
      Return an array containing the names of all currently defined configuration attributes. If there are no such attributes, a zero length array is returned.
      Returns:
      names of all currently defined configuration attributes

    • getInstance

      public abstract 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
      Throws:
      LogConfigurationException - if a suitable Log instance cannot be returned

    • getInstance

      public abstract 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)
      Throws:
      LogConfigurationException - if a suitable Log instance cannot be returned

    • release

      public abstract void release()
      Release any internal references to previously created Loginstances returned by this factory. This is useful in environments like servlet containers, which implement application reloading by throwing away a ClassLoader. Dangling references to objects in that class loader would prevent garbage collection.

    • removeAttribute

      public abstract void removeAttribute(String name)
      Remove any configuration attribute associated with the specified name. If there is no such attribute, no action is taken.
      Parameters:
      name - Name of the attribute to remove

    • setAttribute

      public abstract void setAttribute(String name, Object value)
      Set the configuration attribute with the specified name. Calling this with a null value is equivalent to calling removeAttribute(name).
      Parameters:
      name - Name of the attribute to set
      value - Value of the attribute to set, or null to remove any setting for this attribute

    • 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.SLF4FLogFactory).

      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.

      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
      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)
      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

    • releaseAll

      public static void releaseAll()
      Release any internal references to previously created LogFactory instances, after calling the instance method release() on each of them. This is useful in environments like servlet containers, which implement application reloading by throwing away a ClassLoader. Dangling references to objects in that class loader would prevent garbage collection.

    • objectId

      public static String objectId(Object o)
      Returns a string that uniquely identifies the specified object, including its class.

      The returned string is of form "classname@hashcode", i.e. is the same as the return value of the Object.toString() method, but works even when the specified object's class has overridden the toString method.

      Parameters:
      o - may be null.
      Returns:
      a string of form classname@hashcode, or "null" if param o is null.
      Since:
      1.1

    • createFactory

      protected static Object createFactory(String factoryClass, ClassLoader classLoader)
      This method exists to ensure signature compatibility.

    • directGetContextClassLoader

      protected static ClassLoader directGetContextClassLoader()
      This method exists to ensure signature compatibility.

    • getContextClassLoader

      protected static ClassLoader getContextClassLoader() throws LogConfigurationException
      This method exists to ensure signature compatibility.
      Throws:
      LogConfigurationException

    • getClassLoader

      protected static ClassLoader getClassLoader(Class clazz)
      This method exists to ensure signature compatibility.

    • isDiagnosticsEnabled

      protected static boolean isDiagnosticsEnabled()
      This method exists to ensure signature compatibility.

    • logRawDiagnostic

      protected static void logRawDiagnostic(String msg)
      This method exists to ensure signature compatibility.

    • newFactory

      protected static LogFactory newFactory(String factoryClass, ClassLoader classLoader, ClassLoader contextClassLoader)
      This method exists to ensure signature compatibility.

    • newFactory

      protected static LogFactory newFactory(String factoryClass, ClassLoader classLoader)
      This method exists to ensure signature compatibility.