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java.lang.Object org.logicalcobwebs.logging.LogFactory
public abstract class LogFactory
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.
Field Summary | |
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private static java.util.Hashtable |
factories
The previously constructed LogFactory instances, keyed by
the ClassLoader with which it was created. |
static java.lang.String |
FACTORY_DEFAULT
The fully qualified class name of the fallback LogFactory
implementation class to use, if no other can be found. |
static java.lang.String |
FACTORY_PROPERTIES
The name of the properties file to search for. |
static java.lang.String |
FACTORY_PROPERTY
The name of the property used to identify the LogFactory implementation class name. |
protected static java.lang.String |
SERVICE_ID
JDK1.3+ 'Service Provider' specification (http://java.sun.com/j2se/1.3/docs/guide/jar/jar.html) |
Constructor Summary | |
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protected |
LogFactory()
Protected constructor that is not available for public use. |
Method Summary | |
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private static void |
cacheFactory(java.lang.ClassLoader classLoader,
LogFactory factory)
|
abstract java.lang.Object |
getAttribute(java.lang.String name)
Return the configuration attribute with the specified name (if any), or null if there is no such attribute. |
abstract java.lang.String[] |
getAttributeNames()
Return an array containing the names of all currently defined configuration attributes. |
private static LogFactory |
getCachedFactory(java.lang.ClassLoader contextClassLoader)
Check cached factories (keyed by classLoader) |
protected static java.lang.ClassLoader |
getContextClassLoader()
Return the thread context class loader if available. |
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(java.lang.Class clazz)
Convenience method to derive a name from the specified class and call getInstance(String) with it. |
abstract Log |
getInstance(java.lang.String name)
Construct (if necessary) and return a Log instance,
using the factory's current set of configuration attributes. |
static Log |
getLog(java.lang.Class clazz)
Convenience method to return a named logger, without the application having to care about factories. |
static Log |
getLog(java.lang.String name)
Convenience method to return a named logger, without the application having to care about factories. |
protected static LogFactory |
newFactory(java.lang.String factoryClass,
java.lang.ClassLoader classLoader)
Return a new instance of the specified LogFactory
implementation class, loaded by the specified class loader. |
abstract void |
release()
Release any internal references to previously created Log
instances returned by this factory. |
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(java.lang.String name)
Remove any configuration attribute associated with the specified name. |
abstract void |
setAttribute(java.lang.String name,
java.lang.Object value)
Set the configuration attribute with the specified name. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final java.lang.String FACTORY_PROPERTY
public static final java.lang.String FACTORY_DEFAULT
LogFactory
implementation class to use, if no other can be found.
public static final java.lang.String FACTORY_PROPERTIES
protected static final java.lang.String SERVICE_ID
private static java.util.Hashtable factories
LogFactory
instances, keyed by
the ClassLoader
with which it was created.
Constructor Detail |
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protected LogFactory()
Method Detail |
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public abstract java.lang.Object getAttribute(java.lang.String name)
null
if there is no such attribute.
name
- Name of the attribute to returnpublic abstract java.lang.String[] getAttributeNames()
public abstract Log getInstance(java.lang.Class clazz) throws LogConfigurationException
getInstance(String)
with it.
clazz
- Class for which a suitable Log name will be derived
LogConfigurationException
- if a suitable Log
instance cannot be returnedpublic abstract 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.
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 abstract void release()
Log
instances returned by this factory. This is useful 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 abstract void removeAttribute(java.lang.String name)
name
- Name of the attribute to removepublic abstract void setAttribute(java.lang.String name, java.lang.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 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.logicalcobwebs.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.Propertis
format and
contains the fully qualified name of the implementation class
with the key being the system property defined above.org.logicalcobwebs.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(java.lang.Class clazz) throws LogConfigurationException
clazz
- Class for which a log name will be derived
LogConfigurationException
- if a suitable Log
instance cannot be returnedpublic static Log getLog(java.lang.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 releaseAll()
LogFactory
instances, after calling the instance method release()
on
each of them. This is useful 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.
protected static java.lang.ClassLoader getContextClassLoader() throws LogConfigurationException
LogConfigurationException
- if a suitable class loader
cannot be identified.private static LogFactory getCachedFactory(java.lang.ClassLoader contextClassLoader)
private static void cacheFactory(java.lang.ClassLoader classLoader, LogFactory factory)
protected static LogFactory newFactory(java.lang.String factoryClass, java.lang.ClassLoader classLoader) throws LogConfigurationException
LogFactory
implementation class, loaded by the specified class loader.
If that fails, try the class loader used to load this
(abstract) LogFactory.
factoryClass
- Fully qualified name of the LogFactory
implementation classclassLoader
- ClassLoader from which to load this class
LogConfigurationException
- if a suitable instance
cannot be created
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