Package org.apache.commons.logging.impl

Class LogFactoryImpl

  • public class LogFactoryImpl
extends LogFactory
    Concrete subclass of LogFactory that implements the following algorithm to dynamically select a logging implementation class to instantiate a wrapper for:
    • Use a factory configuration attribute named org.apache.commons.logging.Log to identify the requested implementation class.
    • Use the org.apache.commons.logging.Log system property to identify the requested implementation class.
    • If Log4J is available, return an instance of org.apache.commons.logging.impl.Log4JLogger.
    • If JDK 1.4 or later is available, return an instance of org.apache.commons.logging.impl.Jdk14Logger.
    • Otherwise, return an instance of org.apache.commons.logging.impl.SimpleLog.

    If the selected Log implementation class has a setLogFactory() method that accepts a LogFactory parameter, this method will be called on each newly created instance to identify the associated factory. This makes factory configuration attributes available to the Log instance, if it so desires.

    This factory will remember previously created Log instances for the same name, and will return them on repeated requests to the getInstance() method.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static java.lang.String ALLOW_FLAWED_CONTEXT_PROPERTY
      The name (org.apache.commons.logging.Log.allowFlawedContext) of the system property which can be set true/false to determine system behavior when a bad context class loader is encountered.
      static java.lang.String ALLOW_FLAWED_DISCOVERY_PROPERTY
      The name (org.apache.commons.logging.Log.allowFlawedDiscovery) of the system property which can be set true/false to determine system behavior when a bad logging adapter class is encountered during logging discovery.
      static java.lang.String ALLOW_FLAWED_HIERARCHY_PROPERTY
      The name (org.apache.commons.logging.Log.allowFlawedHierarchy) of the system property which can be set true/false to determine system behavior when a logging adapter class is encountered which has bound to the wrong Log class implementation.
      protected java.util.Hashtable<java.lang.String,​java.lang.Object> attributes
      Configuration attributes.
      protected java.util.Hashtable<java.lang.String,​Log> instances
      The Log instances that have already been created, keyed by logger name.
      static java.lang.String LOG_PROPERTY
      The name (org.apache.commons.logging.Log) of the system property identifying our Log implementation class.
      protected static java.lang.String LOG_PROPERTY_OLD
      The deprecated system property used for backwards compatibility with old versions of JCL.
      protected java.lang.reflect.Constructor<?> logConstructor
      The one-argument constructor of the Log implementation class that will be used to create new instances.
      protected java.lang.Class<?>[] logConstructorSignature
      The signature of the Constructor to be used.
      protected java.lang.reflect.Method logMethod
      The one-argument setLogFactory method of the selected Log method, if it exists.
      protected java.lang.Class<?>[] logMethodSignature
      The signature of the setLogFactory method to be used.

    • Constructor Summary

      Constructors 
      Constructor Description
      LogFactoryImpl()
      Public no-arguments constructor required by the lookup mechanism.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      java.lang.Object getAttribute​(java.lang.String name)
      Gets the configuration attribute with the specified name (if any), or null if there is no such attribute.
      java.lang.String[] getAttributeNames()
      Gets an array containing the names of all currently defined configuration attributes.
      protected static java.lang.ClassLoader getClassLoader​(java.lang.Class<?> clazz)
      Workaround for bug in Java1.2; in theory this method is not needed.
      protected static java.lang.ClassLoader getContextClassLoader()
      Gets the context ClassLoader.
      Log getInstance​(java.lang.Class<?> clazz)
      Convenience method to derive a name from the specified class and call getInstance(String) with it.
      Log getInstance​(java.lang.String name)
      Construct (if necessary) and return a Log instance, using the factory's current set of configuration attributes.
      protected java.lang.String getLogClassName()
      Deprecated.
      Never invoked by this class; subclasses should not assume it will be.
      protected java.lang.reflect.Constructor<?> getLogConstructor()
      Deprecated.
      Never invoked by this class; subclasses should not assume it will be.
      protected static boolean isDiagnosticsEnabled()
      Workaround for bug in Java1.2; in theory this method is not needed.
      protected boolean isJdk13LumberjackAvailable()
      Deprecated.
      Never invoked by this class; subclasses should not assume it will be.
      protected boolean isJdk14Available()
      Deprecated.
      Never invoked by this class; subclasses should not assume it will be.
      protected boolean isLog4JAvailable()
      Deprecated.
      Never invoked by this class; subclasses should not assume it will be.
      protected void logDiagnostic​(java.lang.String msg)
      Output a diagnostic message to a user-specified destination (if the user has enabled diagnostic logging).
      protected Log newInstance​(java.lang.String name)
      Create and return a new Log instance for the specified name.
      void release()
      Releases any internal references to previously created Log instances returned by this factory.
      void removeAttribute​(java.lang.String name)
      Remove any configuration attribute associated with the specified name.
      void setAttribute​(java.lang.String name, java.lang.Object value)
      Sets 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 Detail

      • LOG_PROPERTY

        public static final java.lang.String LOG_PROPERTY
        The name (org.apache.commons.logging.Log) of the system property identifying our Log implementation class.
        See Also:
        Constant Field Values

      • LOG_PROPERTY_OLD

        protected static final java.lang.String LOG_PROPERTY_OLD
        The deprecated system property used for backwards compatibility with old versions of JCL.
        See Also:
        Constant Field Values

      • ALLOW_FLAWED_CONTEXT_PROPERTY

        public static final java.lang.String ALLOW_FLAWED_CONTEXT_PROPERTY
        The name (org.apache.commons.logging.Log.allowFlawedContext) of the system property which can be set true/false to determine system behavior when a bad context class loader is encountered. When set to false, a LogConfigurationException is thrown if LogFactoryImpl is loaded via a child class loader of the TCCL (this should never happen in sane systems).

        Default behavior: true (tolerates bad context class loaders)

        See also method setAttribute.

        See Also:
        Constant Field Values

      • ALLOW_FLAWED_DISCOVERY_PROPERTY

        public static final java.lang.String ALLOW_FLAWED_DISCOVERY_PROPERTY
        The name (org.apache.commons.logging.Log.allowFlawedDiscovery) of the system property which can be set true/false to determine system behavior when a bad logging adapter class is encountered during logging discovery. When set to false, an exception will be thrown and the app will fail to start. When set to true, discovery will continue (though the user might end up with a different logging implementation than they expected).

        Default behavior: true (tolerates bad logging adapters)

        See also method setAttribute.

        See Also:
        Constant Field Values

      • ALLOW_FLAWED_HIERARCHY_PROPERTY

        public static final java.lang.String ALLOW_FLAWED_HIERARCHY_PROPERTY
        The name (org.apache.commons.logging.Log.allowFlawedHierarchy) of the system property which can be set true/false to determine system behavior when a logging adapter class is encountered which has bound to the wrong Log class implementation. When set to false, an exception will be thrown and the app will fail to start. When set to true, discovery will continue (though the user might end up with a different logging implementation than they expected).

        Default behavior: true (tolerates bad Log class hierarchy)

        See also method setAttribute.

        See Also:
        Constant Field Values

      • attributes

        protected java.util.Hashtable<java.lang.String,​java.lang.Object> attributes
        Configuration attributes.

      • instances

        protected java.util.Hashtable<java.lang.String,​Log> instances
        The Log instances that have already been created, keyed by logger name.

      • logConstructor

        protected java.lang.reflect.Constructor<?> logConstructor
        The one-argument constructor of the Log implementation class that will be used to create new instances. This value is initialized by getLogConstructor(), and then returned repeatedly.

      • logConstructorSignature

        protected java.lang.Class<?>[] logConstructorSignature
        The signature of the Constructor to be used.

      • logMethod

        protected java.lang.reflect.Method logMethod
        The one-argument setLogFactory method of the selected Log method, if it exists.

      • logMethodSignature

        protected java.lang.Class<?>[] logMethodSignature
        The signature of the setLogFactory method to be used.

    • Constructor Detail

      • LogFactoryImpl

        public LogFactoryImpl()
        Public no-arguments constructor required by the lookup mechanism.

    • Method Detail

      • getAttribute

        public java.lang.Object getAttribute​(java.lang.String name)
        Gets the configuration attribute with the specified name (if any), or null if there is no such attribute.
        Specified by:
        getAttribute in class LogFactory
        Parameters:
        name - Name of the attribute to return
        Returns:
        the configuration attribute with the specified name.

      • getAttributeNames

        public java.lang.String[] getAttributeNames()
        Gets an array containing the names of all currently defined configuration attributes. If there are no such attributes, a zero length array is returned.
        Specified by:
        getAttributeNames in class LogFactory
        Returns:
        an array containing the names of all currently defined configuration attributes

      • getInstance

        public Log getInstance​(java.lang.Class<?> clazz)
                throws LogConfigurationException
        Convenience method to derive a name from the specified class and call getInstance(String) with it.
        Specified by:
        getInstance in class LogFactory
        Parameters:
        clazz - Class for which a suitable Log name will be derived
        Returns:
        a name from the specified class.
        Throws:
        LogConfigurationException - if a suitable Log instance cannot be returned

      • getInstance

        public Log getInstance​(java.lang.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.

        Specified by:
        getInstance in class LogFactory
        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.
        Throws:
        LogConfigurationException - if a suitable Log instance cannot be returned

      • getLogClassName

        @Deprecated
protected java.lang.String getLogClassName()
        Deprecated.
        Never invoked by this class; subclasses should not assume it will be.
        Gets the fully qualified Java class name of the Log implementation we will be using.
        Returns:
        the fully qualified Java class name of the Log implementation we will be using.

      • getLogConstructor

        @Deprecated
protected java.lang.reflect.Constructor<?> getLogConstructor()
                                                      throws LogConfigurationException
        Deprecated.
        Never invoked by this class; subclasses should not assume it will be.
        Gets the Constructor that can be called to instantiate new Log instances.

        IMPLEMENTATION NOTE - Race conditions caused by calling this method from more than one thread are ignored, because the same Constructor instance will ultimately be derived in all circumstances.

        Returns:
        the Constructor that can be called to instantiate new Log instances.
        Throws:
        LogConfigurationException - if a suitable constructor cannot be returned

      • isJdk13LumberjackAvailable

        @Deprecated
protected boolean isJdk13LumberjackAvailable()
        Deprecated.
        Never invoked by this class; subclasses should not assume it will be.
        Tests whether JDK 1.3 with Lumberjack logging available.
        Returns:
        whether JDK 1.3 with Lumberjack logging available.

      • isJdk14Available

        @Deprecated
protected boolean isJdk14Available()
        Deprecated.
        Never invoked by this class; subclasses should not assume it will be.
        Tests true whether JDK 1.4 or later logging is available. Also checks that the Throwable class supports getStackTrace(), which is required by Jdk14Logger.
        Returns:
        Whether JDK 1.4 or later logging is available.

      • isLog4JAvailable

        @Deprecated
protected boolean isLog4JAvailable()
        Deprecated.
        Never invoked by this class; subclasses should not assume it will be.
        Tests whether a Log4J implementation available.
        Returns:
        whether a Log4J implementation available.

      • logDiagnostic

        protected void logDiagnostic​(java.lang.String msg)
        Output a diagnostic message to a user-specified destination (if the user has enabled diagnostic logging).
        Parameters:
        msg - diagnostic message
        Since:
        1.1

      • release

        public void release()
        Releases any internal references to previously created Log instances 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.
        Specified by:
        release in class LogFactory

      • removeAttribute

        public void removeAttribute​(java.lang.String name)
        Remove any configuration attribute associated with the specified name. If there is no such attribute, no action is taken.
        Specified by:
        removeAttribute in class LogFactory
        Parameters:
        name - Name of the attribute to remove

      • setAttribute

        public void setAttribute​(java.lang.String name,
                         java.lang.Object value)
        Sets the configuration attribute with the specified name. Calling this with a null value is equivalent to calling removeAttribute(name).

        This method can be used to set logging configuration programmatically rather than via system properties. It can also be used in code running within a container (such as a webapp) to configure behavior on a per-component level instead of globally as system properties would do. To use this method instead of a system property, call 

         LogFactory.getFactory().setAttribute(...)

        This must be done before the first Log object is created; configuration changes after that point will be ignored.

        This method is also called automatically if LogFactory detects a commons-logging.properties file; every entry in that file is set automatically as an attribute here.

        Specified by:
        setAttribute in class LogFactory
        Parameters:
        name - Name of the attribute to set
        value - Value of the attribute to set, or null to remove any setting for this attribute