neon.common.files.FileUtils.java Source code

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Here is the source code for neon.common.files.FileUtils.java

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/*
 *   Neon, a roguelike engine.
 *   Copyright (C) 2017 - Maarten Driesen
 * 
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package neon.common.files;

import java.io.File;
import java.io.IOException;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Collections;
import java.util.Set;
import java.util.logging.Logger;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.TreeTraverser;
import com.google.common.io.Files;
import com.google.common.io.MoreFiles;
import com.google.common.io.RecursiveDeleteOption;

/**
 * A collection of utility methods to work with the file system.
 * 
 * @author mdriesen
 *
 */
public final class FileUtils {
    private static final Logger logger = Logger.getGlobal();

    // suppress default constructor for noninstantiability
    private FileUtils() {
        throw new AssertionError();
    }

    /**
     * Copy the contents of a folder to another folder. This method will 
     * overwrite existing items in the destination folder.
     * 
     * @param from
     * @param to
     */
    public static void copyFolder(Path from, Path to) {
        logger.info("copying files from " + from + " to " + to);

        TreeTraverser<File> traverser = Files.fileTreeTraverser();
        for (File file : traverser.preOrderTraversal(from.toFile())) {
            // parent folder should not be copied!
            if (!file.isDirectory()) {
                // construct the destination path from the origin path
                Path origin = Paths.get(file.getPath());
                Path relative = from.relativize(origin);
                Path destination = to.resolve(relative);
                logger.finest("copying file " + relative + " to " + to);

                try {
                    Files.copy(file, destination.toFile());
                } catch (IOException e) {
                    logger.severe("could not write file " + destination);
                }
            } else if (!file.equals(from.toFile())) {
                Path origin = Paths.get(file.getPath());
                Path relative = from.relativize(origin);
                Path destination = to.resolve(relative);

                if (!destination.toFile().exists()) {
                    destination.toFile().mkdirs();
                }
            }
        }
    }

    /**
     * Moves a folder to a new destination. If the destination folder already
     * exists, the contents will be overwritten.
     * 
     * @param from
     * @param to
     * @throws IOException 
     */
    public static void moveFolder(Path from, Path to) {
        logger.info("moving files from " + from + " to " + to);

        TreeTraverser<File> traverser = Files.fileTreeTraverser();

        // first move all the files
        for (File file : traverser.preOrderTraversal(from.toFile())) {
            // parent folder should not be moved!
            if (!file.isDirectory()) {
                // construct the destination path from the origin path
                Path origin = Paths.get(file.getPath());
                Path relative = from.relativize(origin);
                Path destination = to.resolve(relative);

                try {
                    destination.toFile().delete();
                    Files.move(file, destination.toFile());
                } catch (IOException e) {
                    logger.severe("could not write file " + destination);
                }
            } else if (!file.equals(from.toFile())) {
                Path origin = Paths.get(file.getPath());
                Path relative = from.relativize(origin);
                Path destination = to.resolve(relative);

                if (!destination.toFile().exists()) {
                    destination.toFile().mkdirs();
                }
            }
        }

        // then clean up all the leftovers
        clearFolder(from);
    }

    /**
     * Clears all content from the given folder.
     * 
     * @param folder
     */
    public static void clearFolder(Path folder) {
        logger.info("clearing folder " + folder);

        try {
            MoreFiles.deleteDirectoryContents(folder, RecursiveDeleteOption.ALLOW_INSECURE);
        } catch (IOException e) {
            throw new IllegalArgumentException("can't clear folder " + folder, e);
        }
    }

    /**
     * Lists all the files in the given folder. If the given folder does not
     * exist or is not actually a folder, an empty array is returned.
     * 
     * @param path
     * @return   an unmodifiable set
     */
    public static Set<String> listFiles(Path folder) {
        File file = folder.toFile();
        if (file.exists() && file.isDirectory()) {
            return ImmutableSet.copyOf(file.list());
        } else {
            return Collections.emptySet();
        }
    }
}