public class LogFactory extends Object
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.
| Modifier and Type | Field and Description | 
|---|---|
| static String | FACTORY_DEFAULTThe fully qualified class name of the fallback  LogFactoryimplementation class to use, if no other can be found. | 
| static String | FACTORY_PROPERTIESThe name of the properties file to search for. | 
| static String | FACTORY_PROPERTYThe name of the property used to identify the LogFactory implementation
 class name. | 
| static String | HASHTABLE_IMPLEMENTATION_PROPERTYSetting this system property value allows the  Hashtableused to store
 classloaders to be substituted by an alternative implementation. | 
| Modifier and Type | Method and Description | 
|---|---|
| Object | getAttribute(String name)Return the configuration attribute with the specified name (if any),
 or  nullif there is no such attribute. | 
| String[] | getAttributeNames()Return an array containing the names of all currently defined
 configuration attributes. | 
| static LogFactory | getFactory()Construct (if necessary) and return a  LogFactoryinstance, 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  Loginstance,
 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 String | objectId(Object o)Returns a string that uniquely identifies the specified object, including
 its class. | 
| 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  LogFactoryinstances that have been associated with the specified class loader
 (if any), after calling the instance methodrelease()on
 each of them. | 
| static void | releaseAll()Release any internal references to previously created  LogFactoryinstances, after calling the instance methodrelease()on
 each of them. | 
| 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. | 
public static final String FACTORY_PROPERTY
public static final String FACTORY_DEFAULT
LogFactory
 implementation class to use, if no other can be found.public static final String FACTORY_PROPERTIES
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.
 
 Note: LogFactory will print:
 
[ERROR] LogFactory: Load of custom hashtable failedto system error and then continue using a standard Hashtable.
 Usage: Set this property when Java is invoked
 and LogFactory will attempt to load a new instance
 of the given implementation class.
 For example, running the following ant scriptlet:
 
  <java classname="${test.runner}" fork="yes" failonerror="${test.failonerror}">
     ...
     <sysproperty
        key="org.apache.commons.logging.LogFactory.HashtableImpl"
        value="org.apache.commons.logging.AltHashtable"/>
  </java>
 
 will mean that LogFactory will load an instance of
 org.apache.commons.logging.AltHashtable.
 A typical use case is to allow a custom Hashtable implementation using weak references to be substituted. This will allow classloaders to be garbage collected without the need to release them (on 1.3+ JVMs only, of course ;)
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.
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)LogConfigurationException - if a suitable Log
  instance cannot be returnedpublic void release()
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.public Object getAttribute(String name)
null if there is no such attribute.name - Name of the attribute to returnpublic String[] getAttributeNames()
public void removeAttribute(String name)
name - Name of the attribute to removepublic void setAttribute(String name, Object value)
null value is equivalent to calling
 removeAttribute(name).name - Name of the attribute to setvalue - Value of the attribute to set, or null
  to remove any setting for this attributepublic Log getInstance(Class<?> clazz) throws LogConfigurationException
getInstance(String) with it.clazz - Class for which a suitable Log name will be derivedLogConfigurationException - if a suitable Log
  instance cannot be returnedpublic 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.
org.apache.commons.logging.LogFactory system
     property.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.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.
LogConfigurationException - if the implementation class is not
  available or cannot be instantiated.public static Log getLog(Class<?> clazz) throws LogConfigurationException
clazz - Class from which a log name will be derivedLogConfigurationException - if a suitable Log
  instance cannot be returnedpublic static Log getLog(String name) throws LogConfigurationException
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)LogConfigurationException - if a suitable Log
  instance cannot be returnedpublic static void release(ClassLoader classLoader)
LogFactory
 instances that have been associated with the specified class loader
 (if any), after calling the instance method release() on
 each of them.classLoader - ClassLoader for which to release the LogFactorypublic static void releaseAll()
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.public static String objectId(Object o)
The returned string is of form "classname@hashcode", ie 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.
o - may be null.Copyright © 2000-2020 Apache Software Foundation. All Rights Reserved.