java/org/apache/juli/logging/LogFactory.java - tomcat80 - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License.  You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 package org.apache.juli.logging;

 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.util.ServiceLoader;
 import java.util.logging.LogManager;

 /**
  * This is a modified LogFactory that uses a simple {@link ServiceLoader} based
  * discovery mechanism with a default of using JDK based logging. An
  * implementation that uses the full Commons Logging discovery mechanism is
  * available as part of the Tomcat extras download.
  *
  * Why? It is an attempt to strike a balance between simpler code (no discovery)
  * and providing flexibility - particularly for those projects that embed Tomcat
  * or some of Tomcat's components - is an alternative logging
  * implementation is desired.
  *
  * Note that this implementation is not just a wrapper around JDK logging (like
  * the original commons-logging impl). It adds 2 features - a simpler
  * configuration  (which is in fact a subset of log4j.properties) and a
  * formatter that is less ugly.
  *
  * The removal of 'abstract' preserves binary backward compatibility. It is
  * possible to preserve the abstract - and introduce another (hardcoded) factory
  * - but I see no benefit.
  *
  * Since this class is not intended to be extended - all protected methods are
  * removed. This can be changed - but again, there is little value in keeping
  * dead code. Just take a quick look at the removed code ( and it's complexity).
  *
  * --------------
  *
  * Original comment:
  * <p>Factory for creating {@link Log} instances, with discovery and
  * configuration features similar to that employed by standard Java APIs
  * such as JAXP.</p>
  *
  * <p><strong>IMPLEMENTATION NOTE</strong> - This implementation is heavily
  * based on the SAXParserFactory and DocumentBuilderFactory implementations
  * (corresponding to the JAXP pluggability APIs) found in Apache Xerces.</p>
  *
  *
  * @author Craig R. McClanahan
  * @author Costin Manolache
  * @author Richard A. Sitze
  */
 public class LogFactory {

     private static final LogFactory singleton = new LogFactory();

     private final Constructor<? extends Log> discoveredLogConstructor;

     /**
      * Private constructor that is not available for public use.
      */
     private LogFactory() {
         // Look via a ServiceLoader for a Log implementation that has a
         // constructor taking the String name.
         ServiceLoader<Log> logLoader = ServiceLoader.load(Log.class);
         Constructor<? extends Log> m=null;
         for (Log log: logLoader) {
             Class<? extends Log> c=log.getClass();
             try {
                 m=c.getConstructor(String.class);
                 break;
             }
             catch (NoSuchMethodException | SecurityException e) {
                 throw new Error(e);
             }
         }
         discoveredLogConstructor=m;
     }


     // --------------------------------------------------------- Public Methods

     // only those 2 methods need to change to use a different direct logger.

     /**
      * <p>Construct (if necessary) and return a <code>Log</code> instance,
      * using the factory's current set of configuration attributes.</p>
      *
      * <p><strong>NOTE</strong> - Depending upon the implementation of
      * the <code>LogFactory</code> you are using, the <code>Log</code>
      * 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.</p>
      *
      * @param name Logical name of the <code>Log</code> instance to be
      *  returned (the meaning of this name is only known to the underlying
      *  logging implementation that is being wrapped)
      *
      * @exception LogConfigurationException if a suitable <code>Log</code>
      *  instance cannot be returned
      */
     public Log getInstance(String name) throws LogConfigurationException {
         if (discoveredLogConstructor == null) {
             return DirectJDKLog.getInstance(name);
         }

         try {
             return discoveredLogConstructor.newInstance(name);
         } catch (InstantiationException | IllegalAccessException | IllegalArgumentException |
                 InvocationTargetException e) {
             throw new LogConfigurationException(e);
         }
     }


     /**
      * Convenience method to derive a name from the specified class and
      * call <code>getInstance(String)</code> with it.
      *
      * @param clazz Class for which a suitable Log name will be derived
      *
      * @exception LogConfigurationException if a suitable <code>Log</code>
      *  instance cannot be returned
      */
     public Log getInstance(Class<?> clazz) throws LogConfigurationException {
         return getInstance( clazz.getName());
     }


     // ------------------------------------------------------- Static Variables


     // --------------------------------------------------------- Static Methods


     /**
      * <p>Construct (if necessary) and return a <code>LogFactory</code>
      * instance, using the following ordered lookup procedure to determine
      * the name of the implementation class to be loaded.</p>
      * <ul>
      * <li>The <code>org.apache.commons.logging.LogFactory</code> system
      *     property.</li>
      * <li>The JDK 1.3 Service Discovery mechanism</li>
      * <li>Use the properties file <code>commons-logging.properties</code>
      *     file, if found in the class path of this class.  The configuration
      *     file is in standard <code>java.util.Properties</code> format and
      *     contains the fully qualified name of the implementation class
      *     with the key being the system property defined above.</li>
      * <li>Fall back to a default implementation class
      *     (<code>org.apache.commons.logging.impl.LogFactoryImpl</code>).</li>
      * </ul>
      *
      * <p><em>NOTE</em> - If the properties file method of identifying the
      * <code>LogFactory</code> implementation class is utilized, all of the
      * properties defined in this file will be set as configuration attributes
      * on the corresponding <code>LogFactory</code> instance.</p>
      *
      * @exception LogConfigurationException if the implementation class is not
      *  available or cannot be instantiated.
      */
     public static LogFactory getFactory() throws LogConfigurationException {
         return singleton;
     }


     /**
      * Convenience method to return a named logger, without the application
      * having to care about factories.
      *
      * @param clazz Class from which a log name will be derived
      *
      * @exception LogConfigurationException if a suitable <code>Log</code>
      *  instance cannot be returned
      */
     public static Log getLog(Class<?> clazz)
         throws LogConfigurationException {
         return (getFactory().getInstance(clazz));

     }


     /**
      * Convenience method to return a named logger, without the application
      * having to care about factories.
      *
      * @param name Logical name of the <code>Log</code> instance to be
      *  returned (the meaning of this name is only known to the underlying
      *  logging implementation that is being wrapped)
      *
      * @exception LogConfigurationException if a suitable <code>Log</code>
      *  instance cannot be returned
      */
     public static Log getLog(String name)
         throws LogConfigurationException {
         return (getFactory().getInstance(name));

     }


     /**
      * Release any internal references to previously created {@link LogFactory}
      * instances that have been associated with the specified class loader
      * (if any), after calling the instance method <code>release()</code> on
      * each of them.
      *
      * @param classLoader ClassLoader for which to release the LogFactory
      */
     public static void release(ClassLoader classLoader) {
         // JULI's log manager looks at the current classLoader so there is no
         // need to use the passed in classLoader, the default implementation
         // does not so calling reset in that case will break things
         if (!LogManager.getLogManager().getClass().getName().equals(
                 "java.util.logging.LogManager")) {
             LogManager.getLogManager().reset();
         }
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	package org.apache.juli.logging;

	import java.lang.reflect.Constructor;
	import java.lang.reflect.InvocationTargetException;
	import java.util.ServiceLoader;
	import java.util.logging.LogManager;

	/**
	* This is a modified LogFactory that uses a simple {@link ServiceLoader} based
	* discovery mechanism with a default of using JDK based logging. An
	* implementation that uses the full Commons Logging discovery mechanism is
	* available as part of the Tomcat extras download.
	*
	* Why? It is an attempt to strike a balance between simpler code (no discovery)
	* and providing flexibility - particularly for those projects that embed Tomcat
	* or some of Tomcat's components - is an alternative logging
	* implementation is desired.
	*
	* Note that this implementation is not just a wrapper around JDK logging (like
	* the original commons-logging impl). It adds 2 features - a simpler
	* configuration (which is in fact a subset of log4j.properties) and a
	* formatter that is less ugly.
	*
	* The removal of 'abstract' preserves binary backward compatibility. It is
	* possible to preserve the abstract - and introduce another (hardcoded) factory
	* - but I see no benefit.
	*
	* Since this class is not intended to be extended - all protected methods are
	* removed. This can be changed - but again, there is little value in keeping
	* dead code. Just take a quick look at the removed code ( and it's complexity).
	*
	* --------------
	*
	* Original comment:
	* <p>Factory for creating {@link Log} instances, with discovery and
	* configuration features similar to that employed by standard Java APIs
	* such as JAXP.</p>
	*
	* <p><strong>IMPLEMENTATION NOTE</strong> - This implementation is heavily
	* based on the SAXParserFactory and DocumentBuilderFactory implementations
	* (corresponding to the JAXP pluggability APIs) found in Apache Xerces.</p>
	*
	*
	* @author Craig R. McClanahan
	* @author Costin Manolache
	* @author Richard A. Sitze
	*/
	public class LogFactory {

	private static final LogFactory singleton = new LogFactory();

	private final Constructor<? extends Log> discoveredLogConstructor;

	/**
	* Private constructor that is not available for public use.
	*/
	private LogFactory() {
	// Look via a ServiceLoader for a Log implementation that has a
	// constructor taking the String name.
	ServiceLoader<Log> logLoader = ServiceLoader.load(Log.class);
	Constructor<? extends Log> m=null;
	for (Log log: logLoader) {
	Class<? extends Log> c=log.getClass();
	try {
	m=c.getConstructor(String.class);
	break;
	}
	catch (NoSuchMethodException \| SecurityException e) {
	throw new Error(e);
	}
	}
	discoveredLogConstructor=m;
	}


	// --------------------------------------------------------- Public Methods

	// only those 2 methods need to change to use a different direct logger.

	/**
	* <p>Construct (if necessary) and return a <code>Log</code> instance,
	* using the factory's current set of configuration attributes.</p>
	*
	* <p><strong>NOTE</strong> - Depending upon the implementation of
	* the <code>LogFactory</code> you are using, the <code>Log</code>
	* 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.</p>
	*
	* @param name Logical name of the <code>Log</code> instance to be
	* returned (the meaning of this name is only known to the underlying
	* logging implementation that is being wrapped)
	*
	* @exception LogConfigurationException if a suitable <code>Log</code>
	* instance cannot be returned
	*/
	public Log getInstance(String name) throws LogConfigurationException {
	if (discoveredLogConstructor == null) {
	return DirectJDKLog.getInstance(name);
	}

	try {
	return discoveredLogConstructor.newInstance(name);
	} catch (InstantiationException \| IllegalAccessException \| IllegalArgumentException \|
	InvocationTargetException e) {
	throw new LogConfigurationException(e);
	}
	}


	/**
	* Convenience method to derive a name from the specified class and
	* call <code>getInstance(String)</code> with it.
	*
	* @param clazz Class for which a suitable Log name will be derived
	*
	* @exception LogConfigurationException if a suitable <code>Log</code>
	* instance cannot be returned
	*/
	public Log getInstance(Class<?> clazz) throws LogConfigurationException {
	return getInstance( clazz.getName());
	}


	// ------------------------------------------------------- Static Variables


	// --------------------------------------------------------- Static Methods


	/**
	* <p>Construct (if necessary) and return a <code>LogFactory</code>
	* instance, using the following ordered lookup procedure to determine
	* the name of the implementation class to be loaded.</p>
	* <ul>
	* <li>The <code>org.apache.commons.logging.LogFactory</code> system
	* property.</li>
	* <li>The JDK 1.3 Service Discovery mechanism</li>
	* <li>Use the properties file <code>commons-logging.properties</code>
	* file, if found in the class path of this class. The configuration
	* file is in standard <code>java.util.Properties</code> format and
	* contains the fully qualified name of the implementation class
	* with the key being the system property defined above.</li>
	* <li>Fall back to a default implementation class
	* (<code>org.apache.commons.logging.impl.LogFactoryImpl</code>).</li>
	* </ul>
	*
	* <p><em>NOTE</em> - If the properties file method of identifying the
	* <code>LogFactory</code> implementation class is utilized, all of the
	* properties defined in this file will be set as configuration attributes
	* on the corresponding <code>LogFactory</code> instance.</p>
	*
	* @exception LogConfigurationException if the implementation class is not
	* available or cannot be instantiated.
	*/
	public static LogFactory getFactory() throws LogConfigurationException {
	return singleton;
	}


	/**
	* Convenience method to return a named logger, without the application
	* having to care about factories.
	*
	* @param clazz Class from which a log name will be derived
	*
	* @exception LogConfigurationException if a suitable <code>Log</code>
	* instance cannot be returned
	*/
	public static Log getLog(Class<?> clazz)
	throws LogConfigurationException {
	return (getFactory().getInstance(clazz));

	}


	/**
	* Convenience method to return a named logger, without the application
	* having to care about factories.
	*
	* @param name Logical name of the <code>Log</code> instance to be
	* returned (the meaning of this name is only known to the underlying
	* logging implementation that is being wrapped)
	*
	* @exception LogConfigurationException if a suitable <code>Log</code>
	* instance cannot be returned
	*/
	public static Log getLog(String name)
	throws LogConfigurationException {
	return (getFactory().getInstance(name));

	}


	/**
	* Release any internal references to previously created {@link LogFactory}
	* instances that have been associated with the specified class loader
	* (if any), after calling the instance method <code>release()</code> on
	* each of them.
	*
	* @param classLoader ClassLoader for which to release the LogFactory
	*/
	public static void release(ClassLoader classLoader) {
	// JULI's log manager looks at the current classLoader so there is no
	// need to use the passed in classLoader, the default implementation
	// does not so calling reset in that case will break things
	if (!LogManager.getLogManager().getClass().getName().equals(
	"java.util.logging.LogManager")) {
	LogManager.getLogManager().reset();
	}
	}
	}