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.fuin.vfs2.filter; import java.io.Serializable; import org.apache.commons.vfs2.FileContent; import org.apache.commons.vfs2.FileFilter; import org.apache.commons.vfs2.FileObject; import org.apache.commons.vfs2.FileSelectInfo; import org.apache.commons.vfs2.FileSystemException; import org.apache.commons.vfs2.FileType; /** * This filter accepts files or directories that are empty. * <p> * If the <code>File</code> is a directory it checks that it contains no files. * <p> * Example, showing how to print out a list of the current directory's empty * files/directories: * * <pre> * FileSystemManager fsManager = VFS.getManager(); * FileObject dir = fsManager.toFileObject(new File(".")); * FileObject[] files = dir.findFiles(new FileFilterSelector(EmptyFileFilter.EMPTY)); * for (int i = 0; i < files.length; i++) { * System.out.println(files[i]); * } * </pre> * * <p> * Example, showing how to print out a list of the current directory's non-empty * files/directories: * * <pre> * FileSystemManager fsManager = VFS.getManager(); * FileObject dir = fsManager.toFileObject(new File(".")); * FileObject[] files = dir.findFiles(new FileFilterSelector(EmptyFileFilter.NOT_EMPTY)); * for (int i = 0; i < files.length; i++) { * System.out.println(files[i]); * } * </pre> * * @author This code was originally ported from Apache Commons IO File Filter * @see "http://commons.apache.org/proper/commons-io/" */ public class EmptyFileFilter implements FileFilter, Serializable { private static final long serialVersionUID = 1L; /** Singleton instance of <i>empty</i> filter. */ public static final FileFilter EMPTY = new EmptyFileFilter(); /** Singleton instance of <i>not-empty</i> filter. */ public static final FileFilter NOT_EMPTY = new NotFileFilter(EMPTY); /** * Restrictive constructor. */ protected EmptyFileFilter() { } /** * Checks to see if the file is empty. A non-existing file is also * considered empty. * * @param fileInfo * the file or directory to check * * @return {@code true} if the file or directory is <i>empty</i>, otherwise * {@code false}. */ @Override public boolean accept(final FileSelectInfo fileInfo) { final FileObject file = fileInfo.getFile(); try { if (!file.exists()) { return true; } if (file.getType() == FileType.FOLDER) { final FileObject[] files = file.getChildren(); return files == null || files.length == 0; } final FileContent content = file.getContent(); try { return content.getSize() == 0; } finally { content.close(); } } catch (final FileSystemException ex) { throw new RuntimeException(ex); } } }