| /* $Id: LogUtils.java,v 1.8 2004/05/10 06:44:13 skitching Exp $ |
| * |
| * Copyright 2003-2004 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.digester.plugins; |
| |
| import org.apache.commons.digester.Digester; |
| import org.apache.commons.logging.Log; |
| |
| /** |
| * Simple utility class to assist in logging. |
| * <p> |
| * This class is intended only for the use of the code in the |
| * plugins packages. No "user" code should use this package. |
| * <p> |
| * The Digester module has an interesting approach to logging: |
| * all logging should be done via the Log object stored on the |
| * digester instance that the object *doing* the logging is associated |
| * with. |
| * <p> |
| * This is done because apparently some "container"-type applications |
| * such as Avalon and Tomcat need to be able to configure different logging |
| * for different <i>instances</i> of the Digester class which have been |
| * loaded from the same ClassLoader [info from Craig McClanahan]. |
| * Not only the logging of the Digester instance should be affected; all |
| * objects associated with that Digester instance should obey the |
| * reconfiguration of their owning Digester instance's logging. The current |
| * solution is to force all objects to output logging info via a single |
| * Log object stored on the Digester instance they are associated with. |
| * <p> |
| * Of course this causes problems if logging is attempted before an |
| * object <i>has</i> a valid reference to its owning Digester. The |
| * getLogging method provided here resolves this issue by returning a |
| * Log object which silently discards all logging output in this |
| * situation. |
| * <p> |
| * And it also implies that logging filtering can no longer be applied |
| * to subcomponents of the Digester, because all logging is done via |
| * a single Log object (a single Category). C'est la vie... |
| * |
| * @since 1.6 |
| */ |
| |
| class LogUtils { |
| |
| /** |
| * Get the Log object associated with the specified Digester instance, |
| * or a "no-op" logging object if the digester reference is null. |
| * <p> |
| * You should use this method instead of digester.getLogger() in |
| * any situation where the digester might be null. |
| */ |
| static Log getLogger(Digester digester) { |
| if (digester == null) { |
| return new org.apache.commons.logging.impl.NoOpLog(); |
| } |
| |
| return digester.getLogger(); |
| } |
| } |