edu.internet2.middleware.grouperClientExt.org.apache.commons.logging.impl

Class LogFactoryImpl

java.lang.Object

edu.internet2.middleware.grouperClientExt.org.apache.commons.logging.LogFactory

edu.internet2.middleware.grouperClientExt.org.apache.commons.logging.impl.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.

Version:

$Revision: 1.1 $ $Date: 2008-11-30 10:57:27 $

Field Summary

Fields

Modifier and Type	Field and Description
static 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 behaviour when a bad context-classloader is encountered.
static 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 behaviour when a bad logging adapter class is encountered during logging discovery.
static 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 behaviour when a logging adapter class is encountered which has bound to the wrong Log class implementation.
protected Hashtable	attributes Configuration attributes.
protected Hashtable	instances The Log instances that have already been created, keyed by logger name.
static String	LOG_PROPERTY The name (org.apache.commons.logging.Log) of the system property identifying our Log implementation class.
protected static String	LOG_PROPERTY_OLD The deprecated system property used for backwards compatibility with old versions of JCL.
protected Constructor	logConstructor The one-argument constructor of the Log implementation class that will be used to create new instances.
protected Class[]	logConstructorSignature The signature of the Constructor to be used.
protected Method	logMethod The one-argument setLogFactory method of the selected Log method, if it exists.
protected Class[]	logMethodSignature The signature of the setLogFactory method to be used.

Fields inherited from class edu.internet2.middleware.grouperClientExt.org.apache.commons.logging.LogFactory

DIAGNOSTICS_DEST_PROPERTY, factories, FACTORY_DEFAULT, FACTORY_PROPERTIES, FACTORY_PROPERTY, HASHTABLE_IMPLEMENTATION_PROPERTY, nullClassLoaderFactory, PRIORITY_KEY, SERVICE_ID, TCCL_KEY

Constructor Summary

Constructors

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

Method Summary

Methods

Modifier and Type	Method and Description
Object	getAttribute(String name) Return the configuration attribute with the specified name (if any), or null if there is no such attribute.
String[]	getAttributeNames() Return an array containing the names of all currently defined configuration attributes.
protected static ClassLoader	getClassLoader(Class clazz) Workaround for bug in Java1.2; in theory this method is not needed.
protected static ClassLoader	getContextClassLoader() Gets the context classloader.
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.
protected String	getLogClassName() Deprecated. Never invoked by this class; subclasses should not assume it will be.
protected 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(String msg) Output a diagnostic message to a user-specified destination (if the user has enabled diagnostic logging).
protected Log	newInstance(String name) Create and return a new Log instance for the specified name.
void	release() Release any internal references to previously created Log instances returned by this factory.
void	removeAttribute(String name) Remove any configuration attribute associated with the specified name.
void	setAttribute(String name, Object value) Set the configuration attribute with the specified name.

Methods inherited from class edu.internet2.middleware.grouperClientExt.org.apache.commons.logging.LogFactory

createFactory, directGetContextClassLoader, getFactory, getLog, getLog, logRawDiagnostic, newFactory, newFactory, objectId, release, releaseAll

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 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 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 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 behaviour when a bad context-classloader is encountered. When set to false, a LogConfigurationException is thrown if LogFactoryImpl is loaded via a child classloader of the TCCL (this should never happen in sane systems). Default behaviour: true (tolerates bad context classloaders) See also method setAttribute.

See Also:

Constant Field Values

ALLOW_FLAWED_DISCOVERY_PROPERTY

public static final 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 behaviour 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 behaviour: true (tolerates bad logging adapters) See also method setAttribute.

See Also:

Constant Field Values

ALLOW_FLAWED_HIERARCHY_PROPERTY

public static final 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 behaviour 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 behaviour: true (tolerates bad Log class hierarchy) See also method setAttribute.

See Also:

Constant Field Values

attributes

protected Hashtable attributes

Configuration attributes.

instances

protected Hashtable instances

The Log instances that have already been created, keyed by logger name.

logConstructor

protected 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 Class[] logConstructorSignature

The signature of the Constructor to be used.

logMethod

protected Method logMethod

The one-argument setLogFactory method of the selected Log method, if it exists.

logMethodSignature

protected 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 Object getAttribute(String name)

Return 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

getAttributeNames

public 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.

Specified by:

getAttributeNames in class LogFactory

getInstance

public Log getInstance(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

Throws:

LogConfigurationException - if a suitable Log instance cannot be returned

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.

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)

Throws:

LogConfigurationException - if a suitable Log instance cannot be returned

release

public void release()

Release 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(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(String name,
                Object value)

Set 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 behaviour 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

getContextClassLoader

protected static ClassLoader getContextClassLoader()
                                            throws LogConfigurationException

Gets the context classloader. This method is a workaround for a java 1.2 compiler bug.

Throws:

LogConfigurationException

Since:

1.1

isDiagnosticsEnabled

protected static boolean isDiagnosticsEnabled()

Workaround for bug in Java1.2; in theory this method is not needed. See LogFactory.isDiagnosticsEnabled.

getClassLoader

protected static ClassLoader getClassLoader(Class clazz)

Workaround for bug in Java1.2; in theory this method is not needed. See LogFactory.getClassLoader.

Since:

1.1

logDiagnostic

protected void logDiagnostic(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

getLogClassName

protected String getLogClassName()

Deprecated. Never invoked by this class; subclasses should not assume it will be.

Return the fully qualified Java classname of the Log implementation we will be using.

getLogConstructor

protected Constructor getLogConstructor()
                                 throws LogConfigurationException

Deprecated. Never invoked by this class; subclasses should not assume it will be.

Return 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.

Throws:

LogConfigurationException - if a suitable constructor cannot be returned

isJdk13LumberjackAvailable

protected boolean isJdk13LumberjackAvailable()

Deprecated. Never invoked by this class; subclasses should not assume it will be.

Is JDK 1.3 with Lumberjack logging available?

isJdk14Available

protected boolean isJdk14Available()

Deprecated. Never invoked by this class; subclasses should not assume it will be.

Return true if JDK 1.4 or later logging is available. Also checks that the Throwable class supports getStackTrace(), which is required by Jdk14Logger.

isLog4JAvailable

protected boolean isLog4JAvailable()

Deprecated. Never invoked by this class; subclasses should not assume it will be.

Is a Log4J implementation available?

newInstance

protected Log newInstance(String name)
                   throws LogConfigurationException

Create and return a new Log instance for the specified name.

Parameters:

name - Name of the new logger

Throws:

LogConfigurationException - if a new instance cannot be created