org.spout.api.util.config.migration.ConfigurationMigrator.java Source code

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Here is the source code for org.spout.api.util.config.migration.ConfigurationMigrator.java

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/*
 * This file is part of SpoutAPI.
 *
 * Copyright (c) 2011-2012, SpoutDev <http://www.spout.org/>
 * SpoutAPI is licensed under the SpoutDev License Version 1.
 *
 * SpoutAPI is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * In addition, 180 days after any changes are published, you can use the
 * software, incorporating those changes, under the terms of the MIT license,
 * as described in the SpoutDev License Version 1.
 *
 * SpoutAPI 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License,
 * the MIT license and the SpoutDev License Version 1 along with this program.
 * If not, see <http://www.gnu.org/licenses/> for the GNU Lesser General Public
 * License and see <http://www.spout.org/SpoutDevLicenseV1.txt> for the full license,
 * including the MIT license.
 */
package org.spout.api.util.config.migration;

import java.io.File;
import java.io.IOException;
import java.util.Map;

import org.apache.commons.io.FileUtils;
import org.apache.commons.lang3.Validate;
import org.spout.api.exception.ConfigurationException;
import org.spout.api.util.config.Configuration;
import org.spout.api.util.config.ConfigurationNode;
import org.spout.api.util.config.FileConfiguration;

/**
 * A simple migrator for configurations that moves values from one key to another.
 * It can also convert values
 */
public abstract class ConfigurationMigrator {
    private final Configuration configuration;

    protected ConfigurationMigrator(Configuration configuration) {
        Validate.notNull(configuration);
        this.configuration = configuration;
    }

    /**
     * Put together a collection of all keys to be migrated and their associated actions.
     * This can be put in a static HashMap, or generated on each invocation
     *
     * @return The map of configuration keys to their associated actions
     */
    protected abstract Map<String[], MigrationAction> getMigrationActions();

    public Configuration getConfiguration() {
        return configuration;
    }

    /**
     * This method checks whether migration is needed on the {@link Configuration} this instance is constructed with
     *
     * @return Whether migration is needed
     */
    protected abstract boolean shouldMigrate();

    /**
     * Perform migration of the configuration this object was constructed with
     * If migration was not necessary ({@link #shouldMigrate()} returned false), the method invocation will be considered successful.
     * If {@link #configuration} is a {@link org.spout.api.util.config.FileConfiguration}, the file the configuration vas previously stored in will be
     * moved to (file name).old as a backup of the data before migration
     *
     * @throws MigrationException if the configuration could not be successfully migrated
     */
    public void migrate() throws MigrationException {
        if (!shouldMigrate()) {
            return;
        }

        if (configuration instanceof FileConfiguration) {

            File oldFile = ((FileConfiguration) configuration).getFile();
            try {
                FileUtils.moveFile(oldFile, new File(oldFile.getAbsolutePath() + ".old"));
            } catch (IOException e) {
                throw new MigrationException(e);
            }
        }

        for (Map.Entry<String[], MigrationAction> entry : getMigrationActions().entrySet()) {
            final ConfigurationNode existingNode = configuration.getNode(entry.getKey());
            final Object existing = existingNode.getValue();
            existingNode.remove();
            if (existing == null || entry.getValue() == null) {
                continue;
            }
            final String[] newKey = entry.getValue().convertKey(entry.getKey());
            final Object newValue = entry.getValue().convertValue(existing);
            configuration.getNode(newKey).setValue(newValue);
        }
        try {
            configuration.save();
        } catch (ConfigurationException e) {
            throw new MigrationException(e);
        }
    }

}