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.vfs.impl; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.commons.vfs.FileObject; import org.apache.commons.vfs.FileSelector; import org.apache.commons.vfs.FileSystemException; import org.apache.commons.vfs.Selectors; import org.apache.commons.vfs.VfsLog; import org.apache.commons.vfs.provider.AbstractVfsComponent; import org.apache.commons.vfs.provider.FileReplicator; import org.apache.commons.vfs.provider.TemporaryFileStore; import org.apache.commons.vfs.provider.UriParser; import org.apache.commons.vfs.util.Messages; import java.io.File; import java.util.ArrayList; import java.util.Random; /** * A simple file replicator and temporary file store. * * @author <a href="mailto:adammurdoch@apache.org">Adam Murdoch</a> * @version $Revision$ $Date$ */ public class DefaultFileReplicator extends AbstractVfsComponent implements FileReplicator, TemporaryFileStore { private final static Log log = LogFactory.getLog(DefaultFileReplicator.class); private final ArrayList copies = new ArrayList(); private File tempDir; private long filecount; private boolean tempDirMessageLogged; private char[] TMP_RESERVED_CHARS = new char[] { '?', '/', '\\', ' ', '&', '"', '\'', '*', '#', ';', ':', '<', '>', '|' }; /** * constructor to set the location of the temporary directory * * @param tempDir */ public DefaultFileReplicator(final File tempDir) { this.tempDir = tempDir; } public DefaultFileReplicator() { } /** * Initialises this component. */ public void init() throws FileSystemException { if (tempDir == null) { String baseTmpDir = System.getProperty("java.io.tmpdir"); tempDir = new File(baseTmpDir, "vfs_cache").getAbsoluteFile(); } filecount = new Random().nextInt() & 0xffff; if (!tempDirMessageLogged) { final String message = Messages.getString("vfs.impl/temp-dir.info", tempDir); VfsLog.info(getLogger(), log, message); tempDirMessageLogged = true; } } /** * Closes the replicator, deleting all temporary files. */ public void close() { // Delete the temporary files synchronized (copies) { while (copies.size() > 0) { final File file = (File) removeFile(); deleteFile(file); } } // Clean up the temp directory, if it is empty if (tempDir != null && tempDir.exists() && tempDir.list().length == 0) { tempDir.delete(); tempDir = null; } } /** * physically deletes the file from the filesystem */ protected void deleteFile(File file) { try { final FileObject fileObject = getContext().toFileObject(file); fileObject.delete(Selectors.SELECT_ALL); } catch (final FileSystemException e) { final String message = Messages.getString("vfs.impl/delete-temp.warn", file.getName()); VfsLog.warn(getLogger(), log, message, e); } } /** * removes a file from the copies list. Will be used for cleanup. <br/> * Notice: The system awaits that the returning object can be cast to a java.io.File */ protected Object removeFile() { synchronized (copies) { return copies.remove(0); } } /** * removes a instance from the list of copies */ protected void removeFile(Object file) { synchronized (copies) { copies.remove(file); } } /** * Allocates a new temporary file. */ public File allocateFile(final String baseName) throws FileSystemException { // Create a unique-ish file name final String basename = createFilename(baseName); synchronized (this) { filecount++; } final File file = createAndAddFile(tempDir, basename); return file; } protected File createAndAddFile(final File parent, final String basename) throws FileSystemException { final File file = createFile(tempDir, basename); // Keep track to delete later addFile(file); return file; } protected void addFile(Object file) { synchronized (copies) { copies.add(file); } } protected long getFilecount() { return filecount; } /** * create the temporary file name */ protected String createFilename(final String baseName) { // BUG29007 // return baseName + "_" + getFilecount() + ".tmp"; // imario@apache.org: BUG34976 get rid of maybe reserved and dangerous characters // e.g. to allow replication of http://hostname.org/fileservlet?file=abc.txt String safeBasename = UriParser.encode(baseName, TMP_RESERVED_CHARS).replace('%', '_'); return "tmp_" + getFilecount() + "_" + safeBasename; } /** * create the temporary file */ protected File createFile(final File parent, final String name) throws FileSystemException { return new File(parent, UriParser.decode(name)); } /** * Creates a local copy of the file, and all its descendents. */ public File replicateFile(final FileObject srcFile, final FileSelector selector) throws FileSystemException { final String basename = srcFile.getName().getBaseName(); final File file = allocateFile(basename); // Copy from the source file final FileObject destFile = getContext().toFileObject(file); destFile.copyFrom(srcFile, selector); return file; } }