org.apache.xmlbeans.impl.common.XBLogFactory Maven / Gradle / Ivy
/* Copyright 2017, 2018 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.xmlbeans.impl.common;
import java.util.HashMap;
import java.util.Map;
/**
* Provides logging without clients having to mess with
* configuration/initialization.
*
* @author Andrew C. Oliver (acoliver at apache dot org)
* @author Marc Johnson (mjohnson at apache dot org)
* @author Nicola Ken Barozzi (nicolaken at apache.org)
*/
public final class XBLogFactory {
/**
* Map of XBLogger instances, with classes as keys
*/
private static final Map _loggers = new HashMap();
/**
* A common instance of NullLogger, as it does nothing
* we only need the one
*/
private static final XBLogger _nullLogger = new NullLogger();
/**
* The name of the class to use. Initialised the
* first time we need it
*/
static String _loggerClassName = null;
/**
* Construct a XBLogFactory.
*/
private XBLogFactory() {}
/**
* Get a logger, based on a class name
*
* @param theclass the class whose name defines the log
*
* @return a XBLogger for the specified class
*/
public static XBLogger getLogger(final Class> theclass) {
return getLogger(theclass.getName());
}
/**
* Get a logger, based on a String
*
* @param cat the String that defines the log
*
* @return a XBLogger for the specified class
*/
public static XBLogger getLogger(final String cat) {
// If we haven't found out what logger to use yet,
// then do so now
// Don't look it up until we're first asked, so
// that our users can set the system property
// between class loading and first use
if(_loggerClassName == null) {
try {
_loggerClassName = System.getProperty("org.apache.xmlbeans.impl.store.XBLogger");
} catch(Exception e) {
// ignore any exception here
}
// Use the default logger if none specified,
// or none could be fetched
if(_loggerClassName == null) {
_loggerClassName = _nullLogger.getClass().getName();
}
}
// Short circuit for the null logger, which
// ignores all categories
if(_loggerClassName.equals(_nullLogger.getClass().getName())) {
return _nullLogger;
}
// Fetch the right logger for them, creating
// it if that's required
XBLogger logger = _loggers.get(cat);
if (logger == null) {
try {
@SuppressWarnings("unchecked")
Class extends XBLogger> loggerClass =
(Class extends XBLogger>) Class.forName(_loggerClassName);
logger = loggerClass.newInstance();
logger.initialize(cat);
} catch(Exception e) {
// Give up and use the null logger
logger = _nullLogger;
_loggerClassName = _nullLogger.getClass().getName();
}
// Save for next time
_loggers.put(cat, logger);
}
return logger;
}
}
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