path: root/sca-java-1.x/tags/kernel/2.0-alpha-incubating/core/src/main/java/org/apache/tuscany/core/util/FileHelper.java

/*
 * 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.tuscany.core.util;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URL;

public class FileHelper {
    /**
     * The extension separator character.
     */
    private static final char EXTENSION_SEPARATOR = '.';

    /**
     * The Unix separator character.
     */
    private static final char UNIX_SEPARATOR = '/';

    /**
     * The Windows separator character.
     */
    private static final char WINDOWS_SEPARATOR = '\\';
    
    protected FileHelper() {
        
    }
    /**
     * Returns the index of the last directory separator character.
     * <p>
     * This method will handle a file in either Unix or Windows format.
     * The position of the last forward or backslash is returned.
     * <p>
     * The output will be the same irrespective of the machine that the code is running on.
     *
     * @param filename  the filename to find the last path separator in, null returns -1
     * @return the index of the last separator character, or -1 if there
     * is no such character
     */
    public static int indexOfLastSeparator(String filename) {
        if (filename == null) {
            return -1;
        }
        int lastUnixPos = filename.lastIndexOf(UNIX_SEPARATOR);
        int lastWindowsPos = filename.lastIndexOf(WINDOWS_SEPARATOR);
        return Math.max(lastUnixPos, lastWindowsPos);
    }
    
    /**
     * Returns the index of the last extension separator character, which is a dot.
     * <p>
     * This method also checks that there is no directory separator after the last dot.
     * To do this it uses {@link #indexOfLastSeparator(String)} which will
     * handle a file in either Unix or Windows format.
     * <p>
     * The output will be the same irrespective of the machine that the code is running on.
     *
     * @param filename  the filename to find the last path separator in, null returns -1
     * @return the index of the last separator character, or -1 if there
     * is no such character
     */
    public static int indexOfExtension(String filename) {
        if (filename == null) {
            return -1;
        }
        int extensionPos = filename.lastIndexOf(EXTENSION_SEPARATOR);
        int lastSeparator = indexOfLastSeparator(filename);
        return lastSeparator > extensionPos ? -1 : extensionPos;
    }
    
    /**
     * Gets the name minus the path from a full filename.
     * <p>
     * This method will handle a file in either Unix or Windows format.
     * The text after the last forward or backslash is returned.
     * <pre>
     * a/b/c.txt --> c.txt
     * a.txt     --> a.txt
     * a/b/c     --> c
     * a/b/c/    --> ""
     * </pre>
     * <p>
     * The output will be the same irrespective of the machine that the code is running on.
     *
     * @param fileName  the filename to query, null returns null
     * @return the name of the file without the path, or an empty string if none exists
     */
    public static String getName(String fileName) {
        if (fileName == null) {
            return null;
        }
        int index = indexOfLastSeparator(fileName);
        return fileName.substring(index + 1);
    }
    
    /**
     * Gets the extension of a filename.
     * <p>
     * This method returns the textual part of the filename after the last dot.
     * There must be no directory separator after the dot.
     * <pre>
     * foo.txt      --> "txt"
     * a/b/c.jpg    --> "jpg"
     * a/b.txt/c    --> ""
     * a/b/c        --> ""
     * </pre>
     * <p>
     * The output will be the same irrespective of the machine that the code is running on.
     *
     * @param filename the filename to retrieve the extension of.
     * @return the extension of the file or an empty string if none exists.
     */
    public static String getExtension(String filename) {
        if (filename == null) {
            return null;
        }
        int index = indexOfExtension(filename);
        if (index == -1) {
            return "";
        } else {
            return filename.substring(index + 1);
        }
    }
    
    /**
     * Make a directory, including any necessary but nonexistent parent
     * directories. If there already exists a file with specified name or
     * the directory cannot be created then an exception is thrown.
     *
     * @param directory  directory to create, not null
     * @throws NullPointerException if the directory is null
     * @throws IOException if the directory cannot be created
     */
    public static void forceMkdir(File directory) throws IOException {
        if (directory.exists()) {
            if (directory.isFile()) {
                String message =
                    "File "
                        + directory
                        + " exists and is "
                        + "not a directory. Unable to create directory.";
                throw new IOException(message);
            }
        } else {
            if (!directory.mkdirs()) {
                String message =
                    "Unable to create directory " + directory;
                throw new IOException(message);
            }
        }
    }
    
    /**
     * Delete a file. If file is a directory, delete it and all sub-directories.
     * <p>
     * The difference between File.delete() and this method are:
     * <ul>
     * <li>A directory to be deleted does not have to be empty.</li>
     * <li>You get exceptions when a file or directory cannot be deleted.
     *      (java.io.File methods returns a boolean)</li>
     * </ul>
     *
     * @param file  file or directory to delete, not null
     * @throws NullPointerException if the directory is null
     * @throws IOException in case deletion is unsuccessful
     */
    public static void forceDelete(File file) throws IOException {
        if (file.isDirectory()) {
            deleteDirectory(file);
        } else {
            if (!file.exists()) {
                throw new FileNotFoundException("File does not exist: " + file);
            }
            if (!file.delete()) {
                String message =
                    "Unable to delete file: " + file;
                throw new IOException(message);
            }
        }
    }
    
    /**
     * Recursively delete a directory.
     *
     * @param directory  directory to delete
     * @throws IOException in case deletion is unsuccessful
     */
    public static void deleteDirectory(File directory)
        throws IOException {
        if (!directory.exists()) {
            return;
        }

        cleanDirectory(directory);
        if (!directory.delete()) {
            String message =
                "Unable to delete directory " + directory + ".";
            throw new IOException(message);
        }
    }

    /**
     * Clean a directory without deleting it.
     *
     * @param directory directory to clean
     * @throws IOException in case cleaning is unsuccessful
     */
    public static void cleanDirectory(File directory) throws IOException {
        if (!directory.exists()) {
            String message = directory + " does not exist";
            throw new IllegalArgumentException(message);
        }

        if (!directory.isDirectory()) {
            String message = directory + " is not a directory";
            throw new IllegalArgumentException(message);
        }

        File[] files = directory.listFiles();
        if (files == null) {  // null if security restricted
            throw new IOException("Failed to list contents of " + directory);
        }

        IOException exception = null;
        for (int i = 0; i < files.length; i++) {
            File file = files[i];
            try {
                forceDelete(file);
            } catch (IOException ioe) {
                exception = ioe;
            }
        }

        if (null != exception) {
            throw exception;
        }
    }
    
    /**
     * Convert from a <code>URL</code> to a <code>File</code>.
     * <p>
     * From version 1.1 this method will decode the URL.
     * Syntax such as <code>file:///my%20docs/file.txt</code> will be
     * correctly decoded to <code>/my docs/file.txt</code>.
     *
     * @param url  the file URL to convert, null returns null
     * @return the equivalent <code>File</code> object, or <code>null</code>
     *  if the URL's protocol is not <code>file</code>
     * @throws IllegalArgumentException if the file is incorrectly encoded
     */
    public static File toFile(URL url) {
        if (url == null || !url.getProtocol().equals("file")) {
            return null;
        } else {
            String filename = url.getFile().replace('/', File.separatorChar);
            int pos = 0;
            while ((pos = filename.indexOf('%', pos)) >= 0) {  // NOPMD
                if (pos + 2 < filename.length()) {
                    String hexStr = filename.substring(pos + 1, pos + 3);
                    char ch = (char) Integer.parseInt(hexStr, 16);
                    filename = filename.substring(0, pos) + ch + filename.substring(pos + 3);
                }
            }
            return new File(filename);
        }
    }
}