/*
* Copyright 2001-2004 The Apache Software Foundation.
*
* Licensed 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.commons.logging.impl;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.List;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogConfigurationException;
import org.apache.commons.logging.LogFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.spi.LocationAwareLogger;
/**
* <p>
* Concrete subclass of {@link LogFactory} which always delegates to the
* {@link LoggerFactory org.slf4j.LoggerFactory} class.
*
* <p>
* This factory generates instances of {@link SLF4JLog}. It will remember
* previously created instances for the same name, and will return them on
* repeated requests to the <code>getInstance()</code> method.
*
* <p>
* This implementation ignores any configured attributes.
* </p>
*
* @author Rod Waldhoff
* @author Craig R. McClanahan
* @author Richard A. Sitze
* @author Ceki Gülcü
*/
public class SLF4JLogFactory extends LogFactory {
// ----------------------------------------------------------- Constructors
/**
* The {@link org.apache.commons.logging.Log}instances that have already been
* created, keyed by logger name.
*/
Map loggerMap;
/**
* Public no-arguments constructor required by the lookup mechanism.
*/
public SLF4JLogFactory() {
loggerMap = new HashMap();
}
// ----------------------------------------------------- Manifest Constants
/**
* The name of the system property identifying our {@link Log}implementation
* class.
*/
public static final String LOG_PROPERTY = "org.apache.commons.logging.Log";
// ----------------------------------------------------- Instance Variables
/**
* Configuration attributes.
*/
protected Hashtable attributes = new Hashtable();
// --------------------------------------------------------- Public Methods
/**
* Return the configuration attribute with the specified name (if any), or
* <code>null</code> if there is no such attribute.
*
* @param name
* Name of the attribute to return
*/
public Object getAttribute(String name) {
return (attributes.get(name));
}
/**
* Return an array containing the names of all currently defined configuration
* attributes. If there are no such attributes, a zero length array is
* returned.
*/
public String[] getAttributeNames() {
List names = new ArrayList();
Enumeration keys = attributes.keys();
while (keys.hasMoreElements()) {
names.add((String) keys.nextElement());
}
String results[] = new String[names.size()];
for (int i = 0; i < results.length; i++) {
results[i] = (String) names.get(i);
}
return (results);
}
/**
* 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()));
}
/**
* <p>
* Construct (if necessary) and return a <code>Log</code> instance, using
* the factory's current set of configuration attributes.
* </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 {
Log instance = null;
// protect against concurrent access of loggerMap
synchronized (loggerMap) {
instance = (Log) loggerMap.get(name);
if (instance == null) {
Logger logger = LoggerFactory.getLogger(name);
if(logger instanceof LocationAwareLogger) {
instance = new SLF4JLocationAwareLog((LocationAwareLogger) logger);
} else {
instance = new SLF4JLog(logger);
}
loggerMap.put(name, instance);
}
}
return (instance);
}
/**
* Release any internal references to previously created
* {@link org.apache.commons.logging.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 void release() {
// This method is never called by jcl-over-slf4j classes. However,
// in certain deployment scenarios, in particular if jcl-over-slf4j.jar
// is
// in the the web-app class loader and the official commons-logging.jar is
// deployed in some parent class loader (e.g. commons/lib), then it is
// possible
// for the parent class loader to mask the classes shipping in
// jcl-over-slf4j.jar.
System.out.println("WARN: The method " + SLF4JLogFactory.class
+ "#release() was invoked.");
System.out
.println("WARN: Please see http://www.slf4j.org/codes.html#release for an explanation.");
System.out.flush();
}
/**
* Remove any configuration attribute associated with the specified name. If
* there is no such attribute, no action is taken.
*
* @param name
* Name of the attribute to remove
*/
public void removeAttribute(String name) {
attributes.remove(name);
}
/**
* Set the configuration attribute with the specified name. Calling this with
* a <code>null</code> value is equivalent to calling
* <code>removeAttribute(name)</code>.
*
* @param name
* Name of the attribute to set
* @param value
* Value of the attribute to set, or <code>null</code> to remove
* any setting for this attribute
*/
public void setAttribute(String name, Object value) {
if (value == null) {
attributes.remove(name);
} else {
attributes.put(name, value);
}
}
}