at.co.malli.relpm.data.SettingsProvider.java Source code

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Here is the source code for at.co.malli.relpm.data.SettingsProvider.java

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/*
 * Created: 2014-11-23
 * 
 * ====================================================================
 *    The author of this file licenses it to you under the Apache
 *    License, Version 2.0. 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 at.co.malli.relpm.data;

import at.co.malli.lib.gui.ExceptionDisplayer;
import java.net.URL;
import java.util.Iterator;
import org.apache.commons.configuration.CompositeConfiguration;
import org.apache.commons.configuration.ConfigurationException;
import org.apache.commons.configuration.XMLConfiguration;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

/**
 * A small class implementing the singleton design pattern providing a unified interface to the applications settings.
 * @author Dietmar Malli
 */
public class SettingsProvider {
    private static final Logger logger = LogManager.getLogger(SettingsProvider.class.getName());

    //Volatile to prevent VM from optimizing the Double-Checking of theInstance
    private static volatile SettingsProvider theInstance = null;

    /**
     * @return The only existing instance of this class.
     */
    public static SettingsProvider getInstance() {
        if (theInstance == null) {
            //If two threads would try to create a new instance...
            synchronized (SettingsProvider.class) {
                if (theInstance == null)
                    theInstance = new SettingsProvider();
            }
        }

        return theInstance;
    }

    public static final URL defaultsFilename = SettingsProvider.class
            .getResource("/at/co/malli/relpm/RelPM-defaults.xml");
    public static final String userconfigFilename = System.getProperty("user.home")
            + "/.RelPM/RelPM-userconfig.xml";

    private CompositeConfiguration config = new CompositeConfiguration();
    private XMLConfiguration defaults;
    private XMLConfiguration user;

    /**
     * Sets up the object. This is only called one time when getInstance() is called the first time.
     */
    public SettingsProvider() {
        try {
            defaults = new XMLConfiguration(defaultsFilename);
            user = new XMLConfiguration(userconfigFilename);
        } catch (ConfigurationException ex) {
            if (ex.getMessage().equals("Cannot locate configuration source " + userconfigFilename)) {
                logger.trace(userconfigFilename + " not found... Creating default...");
                createDefaultConfig();
            } else {
                logger.error(ex.getMessage());
                ExceptionDisplayer.showErrorMessage(ex);
            }
        }
        config.addConfiguration(user, true);
        config.addConfiguration(defaults, false);
    }

    /**
     * Set up the default configuration in memory.
     */
    private void createDefaultConfig() {
        user = new XMLConfiguration();

        Iterator<String> i = defaults.getKeys();
        while (i.hasNext()) {
            String key = i.next();
            Object value = defaults.getProperty(key);
            user.setProperty(key, value);
        }
        try {
            user.save(userconfigFilename);
        } catch (ConfigurationException ex) {
            logger.error(ex.getMessage());
            ExceptionDisplayer.showErrorMessage(ex);
        }
    }

    /**
     * Writes the usermodified configuration into the user's homedirectory.
     * @throws ConfigurationException 
     */
    public void writeUserconfig() throws ConfigurationException {
        user.save(userconfigFilename);
    }

    /**
     * @param key String representing the name of the wanted setting from the xml structure. (For example "gui.lastfile")
     * @return The wanted value as an integer.
     */
    public int getInt(String key) {
        return config.getInt(key);
    }

    /**
     * @param key String representing the name of the wanted setting from the xml structure. (For example "gui.lastfile")
     * @return The wanted value as a long.
     */
    public long getLong(String key) {
        return config.getLong(key);
    }

    /**
     * @param key String representing the name of the wanted setting from the xml structure. (For example "gui.lastfile")
     * @return The wanted value as a String.
     */
    public String getString(String key) {
        return config.getString(key);
    }

    /**
     * @param key String representing the name of the wanted setting from the xml structure. (For example "gui.lastfile")
     * @return The wanted value as a boolean.
     */
    public boolean getBoolean(String key) {
        return config.getBoolean(key);
    }

    /**
     * Writes a new value into the usermodified configuration in memory.
     * @param key String representing the name of the wanted setting from the xml structure. (For example "gui.lastfile")
     * @param value The value to set. (Will usually be saved as Sring on the persistent storage.)
     */
    public void set(String key, Object value) {
        config.setProperty(key, value);
    }
}