fileutils.java

JMule是一个基于Java开发

/*
 * 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;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
import java.util.zip.CRC32;
import java.util.zip.CheckedInputStream;
import java.util.zip.Checksum;

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;
import org.apache.commons.io.output.NullOutputStream;

/**
 * General file manipulation utilities.
 * <p>
 * Facilities are provided in the following areas:
 * <ul>
 * <li>writing to a file
 * <li>reading from a file
 * <li>make a directory including parent directories
 * <li>copying files and directories
 * <li>deleting files and directories
 * <li>converting to and from a URL
 * <li>listing files and directories by filter and extension
 * <li>comparing file content
 * <li>file last changed date
 * <li>calculating a checksum
 * </ul>
 * <p>
 * Origin of code: Excalibur, Alexandria, Commons-Utils
 *
 * @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>
 * @author Stephen Colebourne
 * @author Ian Springer
 * @author Chris Eldredge
 * @author Jim Harrington
 * @author Niall Pemberton
 * @author Sandy McArthur
 * @version $Id: FileUtils.java,v 1.1 2008/07/31 16:43:18 javajox Exp $
 */
public class FileUtils {

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

    /**
     * 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;

    /**
     * An empty array of type <code>File</code>.
     */
    public static final File[] EMPTY_FILE_ARRAY = new File[0];

    //-----------------------------------------------------------------------
    /**
     * Opens a {@link FileInputStream} for the specified file, providing better
     * error messages than simply calling <code>new FileInputStream(file)</code>.
     * <p>
     * At the end of the method either the stream will be successfully opened,
     * or an exception will have been thrown.
     * <p>
     * An exception is thrown if the file does not exist.
     * An exception is thrown if the file object exists but is a directory.
     * An exception is thrown if the file exists but cannot be read.
     * 
     * @param file  the file to open for input, must not be <code>null</code>
     * @return a new {@link FileInputStream} for the specified file
     * @throws FileNotFoundException if the file does not exist
     * @throws IOException if the file object is a directory
     * @throws IOException if the file cannot be read
     * @since Commons IO 1.3
     */
    public static FileInputStream openInputStream(File file) throws IOException {
        if (file.exists()) {
            if (file.isDirectory()) {
                throw new IOException("File '" + file + "' exists but is a directory");
            }
            if (file.canRead() == false) {
                throw new IOException("File '" + file + "' cannot be read");
            }
        } else {
            throw new FileNotFoundException("File '" + file + "' does not exist");
        }
        return new FileInputStream(file);
    }

    //-----------------------------------------------------------------------
    /**
     * Opens a {@link FileOutputStream} for the specified file, checking and
     * creating the parent directory if it does not exist.
     * <p>
     * At the end of the method either the stream will be successfully opened,
     * or an exception will have been thrown.
     * <p>
     * The parent directory will be created if it does not exist.
     * The file will be created if it does not exist.
     * An exception is thrown if the file object exists but is a directory.
     * An exception is thrown if the file exists but cannot be written to.
     * An exception is thrown if the parent directory cannot be created.
     * 
     * @param file  the file to open for output, must not be <code>null</code>
     * @return a new {@link FileOutputStream} for the specified file
     * @throws IOException if the file object is a directory
     * @throws IOException if the file cannot be written to
     * @throws IOException if a parent directory needs creating but that fails
     * @since Commons IO 1.3
     */
    public static FileOutputStream openOutputStream(File file) throws IOException {
        if (file.exists()) {
            if (file.isDirectory()) {
                throw new IOException("File '" + file + "' exists but is a directory");
            }
            if (file.canWrite() == false) {
                throw new IOException("File '" + file + "' cannot be written to");
            }
        } else {
            File parent = file.getParentFile();
            if (parent != null && parent.exists() == false) {
                if (parent.mkdirs() == false) {
                    throw new IOException("File '" + file + "' could not be created");
                }
            }
        }
        return new FileOutputStream(file);
    }

    //-----------------------------------------------------------------------
    /**
     * Returns a human-readable version of the file size, where the input
     * represents a specific number of bytes.
     *
     * @param size  the number of bytes
     * @return a human-readable display value (includes units)
     */
    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.
     * <p>
     * NOTE: As from v1.3, this method throws an IOException if the last
     * modified date of the file cannot be set. Also, as from v1.3 this method
     * creates parent directories if they do not exist.
     *
     * @param file  the File to touch
     * @throws IOException If an I/O problem occurs
     */
    public static void touch(File file) throws IOException {
        if (!file.exists()) {
            OutputStream out = openOutputStream(file);
            IOUtils.closeQuietly(out);
        }
        boolean success = file.setLastModified(System.currentTimeMillis());
        if (!success) {
            throw new IOException("Unable to set the last modification time for " + file);
        }
    }

    //-----------------------------------------------------------------------
    /**
     * 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()]);
    }

    //-----------------------------------------------------------------------
    /**
     * Finds files within a given directory (and optionally its
     * subdirectories). All files found are filtered by an IOFileFilter.
     *
     * @param files the collection of files found.
     * @param directory the directory to search in.
     * @param filter the filter to apply to files and directories.
     */
    private static void innerListFiles(Collection files, File directory,
            IOFileFilter filter) {
        File[] found = directory.listFiles((FileFilter) filter);
        if (found != null) {
            for (int i = 0; i < found.length; i++) {
                if (found[i].isDirectory()) {
                    innerListFiles(files, found[i], filter);
                } else {
                    files.add(found[i]);
                }
            }
        }
    }

    /**
     * Finds files within a given directory (and optionally its
     * subdirectories). All files found are filtered by an IOFileFilter.
     * <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>
     * An example: If you want to search through all directories called
     * "temp" you pass in <code>FileFilterUtils.NameFileFilter("temp")</code>
     * <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>.
     *
     * @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 <code>null</code>, 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));