org.apache.commons.logging.impl.SLF4JLogFactory Maven / Gradle / Ivy
/*
* 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 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;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
/**
*
* Concrete subclass of {@link LogFactory} which always delegates to the
* {@link LoggerFactory org.slf4j.LoggerFactory} class.
*
*
* 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 getInstance() method.
*
*
* This implementation ignores any configured attributes.
*
*
* @author Rod Waldhoff
* @author Craig R. McClanahan
* @author Richard A. Sitze
* @author Ceki Gülcü
*/
@SuppressWarnings("rawtypes")
public class SLF4JLogFactory extends LogFactory {
// ----------------------------------------------------------- Constructors
/**
* The {@link org.apache.commons.logging.Log}instances that have already been
* created, keyed by logger name.
*/
ConcurrentMap loggerMap;
/**
* Public no-arguments constructor required by the lookup mechanism.
*/
public SLF4JLogFactory() {
loggerMap = new ConcurrentHashMap<>();
}
// ----------------------------------------------------- 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
* null 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.
*/
@SuppressWarnings("unchecked")
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
* getInstance(String) with it.
*
* @param clazz
* Class for which a suitable Log name will be derived
*
* @exception LogConfigurationException
* if a suitable Log instance cannot be returned
*/
public Log getInstance(Class clazz) throws LogConfigurationException {
return (getInstance(clazz.getName()));
}
/**
*
* Construct (if necessary) and return a Log instance, using
* the factory's current set of configuration attributes.
*
*
* @param 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)
*
* @exception LogConfigurationException
* if a suitable Log instance cannot be returned
*/
public Log getInstance(String name) throws LogConfigurationException {
Log instance = loggerMap.get(name);
if (instance != null) {
return instance;
} else {
Log newInstance;
Logger slf4jLogger = LoggerFactory.getLogger(name);
if (slf4jLogger instanceof LocationAwareLogger) {
newInstance = new SLF4JLocationAwareLog((LocationAwareLogger) slf4jLogger);
} else {
newInstance = new SLF4JLog(slf4jLogger);
}
Log oldInstance = loggerMap.putIfAbsent(name, newInstance);
return oldInstance == null ? newInstance : oldInstance;
}
}
/**
* 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 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 null value is equivalent to calling
* removeAttribute(name).
*
* @param name
* Name of the attribute to set
* @param value
* Value of the attribute to set, or null to remove
* any setting for this attribute
*/
@SuppressWarnings("unchecked")
public void setAttribute(String name, Object value) {
if (value == null) {
attributes.remove(name);
} else {
attributes.put(name, value);
}
}
}