Java tutorial
/* * 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.commons.io; import java.io.File; /** * Keeps track of files awaiting deletion, and deletes them when an associated * marker object is reclaimed by the garbage collector. * <p> * This utility creates a background thread to handle file deletion. * Each file to be deleted is registered with a handler object. * When the handler object is garbage collected, the file is deleted. * <p> * In an environment with multiple class loaders (a servlet container, for * example), you should consider stopping the background thread if it is no * longer needed. This is done by invoking the method * {@link #exitWhenFinished}, typically in * {@link javax.servlet.ServletContextListener#contextDestroyed} or similar. * * @author Noel Bergman * @author Martin Cooper * @version $Id: FileCleaner.java 553012 2007-07-03 23:01:07Z ggregory $ * @deprecated Use {@link FileCleaningTracker} */ public class FileCleaner { /** * The instance to use for the deprecated, static methods. */ static final FileCleaningTracker theInstance = new FileCleaningTracker(); //----------------------------------------------------------------------- /** * Track the specified file, using the provided marker, deleting the file * when the marker instance is garbage collected. * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used. * * @param file the file to be tracked, not null * @param marker the marker object used to track the file, not null * @throws NullPointerException if the file is null * @deprecated Use {@link FileCleaningTracker#track(File, Object)}. */ public static void track(File file, Object marker) { theInstance.track(file, marker); } /** * Track the specified file, using the provided marker, deleting the file * when the marker instance is garbage collected. * The speified deletion strategy is used. * * @param file the file to be tracked, not null * @param marker the marker object used to track the file, not null * @param deleteStrategy the strategy to delete the file, null means normal * @throws NullPointerException if the file is null * @deprecated Use {@link FileCleaningTracker#track(File, Object, FileDeleteStrategy)}. */ public static void track(File file, Object marker, FileDeleteStrategy deleteStrategy) { theInstance.track(file, marker, deleteStrategy); } /** * Track the specified file, using the provided marker, deleting the file * when the marker instance is garbage collected. * The {@link FileDeleteStrategy#NORMAL normal} deletion strategy will be used. * * @param path the full path to the file to be tracked, not null * @param marker the marker object used to track the file, not null * @throws NullPointerException if the path is null * @deprecated Use {@link FileCleaningTracker#track(String, Object)}. */ public static void track(String path, Object marker) { theInstance.track(path, marker); } /** * Track the specified file, using the provided marker, deleting the file * when the marker instance is garbage collected. * The speified deletion strategy is used. * * @param path the full path to the file to be tracked, not null * @param marker the marker object used to track the file, not null * @param deleteStrategy the strategy to delete the file, null means normal * @throws NullPointerException if the path is null * @deprecated Use {@link FileCleaningTracker#track(String, Object, FileDeleteStrategy)}. */ public static void track(String path, Object marker, FileDeleteStrategy deleteStrategy) { theInstance.track(path, marker, deleteStrategy); } //----------------------------------------------------------------------- /** * Retrieve the number of files currently being tracked, and therefore * awaiting deletion. * * @return the number of files being tracked * @deprecated Use {@link FileCleaningTracker#getTrackCount()}. */ public static int getTrackCount() { return theInstance.getTrackCount(); } /** * Call this method to cause the file cleaner thread to terminate when * there are no more objects being tracked for deletion. * <p> * In a simple environment, you don't need this method as the file cleaner * thread will simply exit when the JVM exits. In a more complex environment, * with multiple class loaders (such as an application server), you should be * aware that the file cleaner thread will continue running even if the class * loader it was started from terminates. This can consitute a memory leak. * <p> * For example, suppose that you have developed a web application, which * contains the commons-io jar file in your WEB-INF/lib directory. In other * words, the FileCleaner class is loaded through the class loader of your * web application. If the web application is terminated, but the servlet * container is still running, then the file cleaner thread will still exist, * posing a memory leak. * <p> * This method allows the thread to be terminated. Simply call this method * in the resource cleanup code, such as {@link javax.servlet.ServletContextListener#contextDestroyed}. * One called, no new objects can be tracked by the file cleaner. * @deprecated Use {@link FileCleaningTracker#exitWhenFinished()}. */ public static synchronized void exitWhenFinished() { theInstance.exitWhenFinished(); } /** * Returns the singleton instance, which is used by the deprecated, static methods. * This is mainly useful for code, which wants to support the new * {@link FileCleaningTracker} class while maintain compatibility with the * deprecated {@link FileCleaner}. * * @return the singleton instance */ public static FileCleaningTracker getInstance() { return theInstance; } }