| |
| /* ==================================================================== |
| 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.poi.util; |
| |
| 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 class POILogFactory |
| { |
| |
| /** |
| * Map of POILogger instances, with classes as keys |
| */ |
| private static Map<String,POILogger> _loggers = new HashMap<String,POILogger>();; |
| |
| /** |
| * A common instance of NullLogger, as it does nothing |
| * we only need the one |
| */ |
| private static POILogger _nullLogger = new NullLogger(); |
| /** |
| * The name of the class to use. Initialised the |
| * first time we need it |
| */ |
| private static String _loggerClassName = null; |
| |
| /** |
| * Construct a POILogFactory. |
| */ |
| private POILogFactory() |
| { |
| } |
| |
| /** |
| * Get a logger, based on a class name |
| * |
| * @param theclass the class whose name defines the log |
| * |
| * @return a POILogger for the specified class |
| */ |
| |
| public static POILogger 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 POILogger for the specified class |
| */ |
| |
| public static POILogger getLogger(final String cat) |
| { |
| POILogger logger = null; |
| |
| // 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.poi.util.POILogger"); |
| } catch(Exception e) {} |
| |
| // 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 |
| if (_loggers.containsKey(cat)) { |
| logger = _loggers.get(cat); |
| } else { |
| try { |
| @SuppressWarnings("unchecked") |
| Class<? extends POILogger> loggerClass = |
| (Class<? extends POILogger>)Class.forName(_loggerClassName); |
| logger = loggerClass.newInstance(); |
| logger.initialize(cat); |
| } catch(Exception e) { |
| // Give up and use the null logger |
| logger = _nullLogger; |
| } |
| |
| // Save for next time |
| _loggers.put(cat, logger); |
| } |
| return logger; |
| } |
| } // end public class POILogFactory |