fileutils.java

JAVA 文章管理系统源码

/*
 * Copyright 2001-2004 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.io;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.FileFilter;
import java.io.OutputStream;
import java.net.URL;
import java.util.Collection;
import java.util.Date;

import org.apache.commons.io.filefilter.DirectoryFileFilter;
import org.apache.commons.io.filefilter.FalseFileFilter;
import org.apache.commons.io.filefilter.FileFilterUtils;
import org.apache.commons.io.filefilter.IOFileFilter;
import org.apache.commons.io.filefilter.SuffixFileFilter;
import org.apache.commons.io.filefilter.TrueFileFilter;

/**
 * This class provides basic facilities for manipulating files and file paths.
 *
 * <h3>Path-related methods</h3>
 *
 * <p>Methods exist to retrieve the components of a typical file path. For example
 * <code>/www/hosted/mysite/index.html</code>, can be broken into:
 * <ul>
 *   <li><code>/www/hosted/mysite/</code> -- retrievable through {@link #getPath}</li>
 *   <li><code>index.html</code> -- retrievable through {@link #removePath}</li>
 *   <li><code>/www/hosted/mysite/index</code> -- retrievable through {@link #removeExtension}</li>
 *   <li><code>html</code> -- retrievable through {@link #getExtension}</li>
 * </ul>
 * There are also methods to {@link #catPath concatenate two paths}, {@link #resolveFile resolve a
 * path relative to a File} and {@link #normalize} a path.
 * </p>
 *
 * <h3>File-related methods</h3>
 * <p>
 * There are methods to  create a {@link #toFile File from a URL}, copy a
 * {@link #copyFileToDirectory File to a directory},
 * copy a {@link #copyFile File to another File},
 * copy a {@link #copyURLToFile URL's contents to a File},
 * as well as methods to {@link #deleteDirectory(File) delete} and {@link #cleanDirectory(File)
 * clean} a directory.
 * </p>
 *
 * Common {@link java.io.File} manipulation routines.
 *
 * <h3>Origin of code</h3>
 * <ul>
 *   <li>commons-utils repo</li>
 *   <li>Alexandria's FileUtils.</li>
 *   <li>Avalon Excalibur's IO.</li>
 * </ul>
 *
 * @author <a href="mailto:[e-mail]">Kevin A. Burton</A>
 * @author <a href="mailto:[e-mail]">Scott Sanders</a>
 * @author <a href="mailto:[e-mail]">Daniel Rall</a>
 * @author <a href="mailto:[e-mail]">Christoph.Reck</a>
 * @author <a href="mailto:[e-mail]">Peter Donald</a>
 * @author <a href="mailto:[e-mail]">Jeff Turner</a>
 * @author Matthew Hawthorne
 * @author <a href="mailto:[e-mail]">Jeremias Maerki</a>
 * @version $Id: FileUtils.java,v 1.31 2004/04/24 19:46:16 jeremias Exp $
 */
public class FileUtils {

    /**
     * Instances should NOT be constructed in standard programming.
     */
    public FileUtils() { }

    /**
     * The number of bytes in a kilobyte.
     */
    public static final long ONE_KB = 1024;

    /**
     * The number of bytes in a megabyte.
     */
    public static final long ONE_MB = ONE_KB * ONE_KB;

    /**
     * The number of bytes in a gigabyte.
     */
    public static final long ONE_GB = ONE_KB * ONE_MB;

    /**
     * Returns a human-readable version of the file size (original is in
     * bytes).
     *
     * @param size The number of bytes.
     * @return     A human-readable display value (includes units).
     * @todo need for I18N?
     */
    public static String byteCountToDisplaySize(long size) {
        String displaySize;

        if (size / ONE_GB > 0) {
            displaySize = String.valueOf(size / ONE_GB) + " GB";
        } else if (size / ONE_MB > 0) {
            displaySize = String.valueOf(size / ONE_MB) + " MB";
        } else if (size / ONE_KB > 0) {
            displaySize = String.valueOf(size / ONE_KB) + " KB";
        } else {
            displaySize = String.valueOf(size) + " bytes";
        }

        return displaySize;
    }


    /**
     * Implements the same behaviour as the "touch" utility on Unix. It creates
     * a new file with size 0 or, if the file exists already, it is opened and
     * closed without modifying it, but updating the file date and time.
     * @param file the File to touch
     * @throws IOException If an I/O problem occurs
     */
    public static void touch(File file) throws IOException {
        OutputStream out = new java.io.FileOutputStream(file);
        IOUtils.closeQuietly(out);
    }


    private static void innerListFiles(Collection files, File directory, IOFileFilter filter) {
        File[] found = directory.listFiles((FileFilter)filter);
        for (int i = 0; i < found.length; i++) {
            if (found[i].isDirectory()) {
                innerListFiles(files, found[i], filter);
            } else {
                files.add(found[i]);
            }
        }
    }


    /**
     * Converts a Collection containing java.io.File instanced into array
     * representation. This is to account for the difference between
     * File.listFiles() and FileUtils.listFiles().
     * @param files a Collection containing java.io.File instances
     * @return an array of java.io.File
     */
    public static File[] convertFileCollectionToFileArray(Collection files) {
         return (File[])files.toArray(new File[files.size()]);
    }


    /**
     * <p>Finds files within a given directory (and optionally its 
     * subdirectories). All files found are filtered by an IOFileFilter.
     * </p>
     * <p>If your search should recurse into subdirectories you can pass in 
     * an IOFileFilter for directories. You don't need to bind a 
     * DirectoryFileFilter (via logical AND) to this filter. This method does 
     * that for you.
     * </p>
     * <p>An example: If you want to search through all directories called
     * "temp" you pass in <code>FileFilterUtils.NameFileFilter("temp")</code>
     * </p>
     * <p>Another common usage of this method is find files in a directory
     * tree but ignoring the directories generated CVS. You can simply pass
     * in <code>FileFilterUtils.makeCVSAware(null)</code>.
     * </p>  
     * @param directory the directory to search in
     * @param fileFilter filter to apply when finding files.
     * @param dirFilter optional filter to apply when finding subdirectories. 
     * If this parameter is null, subdirectories will not be included in the
     * search. Use TrueFileFilter.INSTANCE to match all directories.
     * @return an collection of java.io.File with the matching files
     * @see org.apache.commons.io.filefilter.FileFilterUtils
     * @see org.apache.commons.io.filefilter.NameFileFilter
     */
    public static Collection listFiles(File directory, IOFileFilter fileFilter, IOFileFilter dirFilter) {
        if (!directory.isDirectory()) {
            throw new IllegalArgumentException("Parameter 'directory' is not a directory");
        }
        if (fileFilter == null) {
            throw new NullPointerException("Parameter 'fileFilter' is null");
        }
        
        //Setup effective file filter
        IOFileFilter effFileFilter = FileFilterUtils.andFileFilter(fileFilter, 
            FileFilterUtils.notFileFilter(DirectoryFileFilter.INSTANCE));
            
        //Setup effective directory filter
        IOFileFilter effDirFilter;
        if (dirFilter == null) {
            effDirFilter = FalseFileFilter.INSTANCE;
        } else {
            effDirFilter = FileFilterUtils.andFileFilter(dirFilter,
                DirectoryFileFilter.INSTANCE);
        }
        
        //Find files
        Collection files = new java.util.LinkedList();
        innerListFiles(files, directory, 
            FileFilterUtils.orFileFilter(effFileFilter, effDirFilter));
        return files;
    }
    

    /**
     * Converts an array of file extensions to suffixes for use
     * with IOFileFilters.
     * @param extensions an array of extensions. Format: {"java", "xml"}
     * @return an array of suffixes. Format: {".java", ".xml"}
     */
    private static String[] toSuffixes(String[] extensions) {
        String[] suffixes = new String[extensions.length];
        for (int i = 0; i < extensions.length; i++) {
            suffixes[i] = "." + extensions[i];
        }
        return suffixes;
    }


    /**
     * Finds files within a given directory (and optionally its subdirectories)
     * which match an array of extensions. 
     * @param directory the directory to search in
     * @param extensions an array of extensions, ex. {"java","xml"}. If this
     * parameter is null, all files are returned.
     * @param recursive If true all subdirectories are searched, too.
     * @return an collection of java.io.File with the matching files
     */
    public static Collection listFiles(File directory, String[] extensions, boolean recursive) {
        IOFileFilter filter;
        if (extensions == null) {
            filter = TrueFileFilter.INSTANCE;
        } else {
            String[] suffixes = toSuffixes(extensions);
            filter = new SuffixFileFilter(suffixes);
        }
        return listFiles(directory, filter, 
            (recursive ? TrueFileFilter.INSTANCE : FalseFileFilter.INSTANCE));
    }


    /**
     * <p>Compare the contents of two files to determine if they are equal or not.</p>
     * <p>Code origin: Avalon</p>
     *
     * @param file1 the first file
     * @param file2 the second file
     * @return true if the content of the files are equal or they both don't exist, false otherwise
     * @throws IOException in case of an I/O error
     */
    public static boolean contentEquals(File file1, File file2)
            throws IOException {
        boolean file1Exists = file1.exists();
        if (file1Exists != file2.exists()) {
            return false;
        }

        if (!file1Exists) {
            // two not existing files are equal
            return true;
        }

        if (file1.isDirectory() || file2.isDirectory()) {
            // don't want to compare directory contents
            throw new IOException("Can't compare directories, only files");
        }