eu.over9000.skadi.io.PersistenceHandler.java Source code

Introduction

Here is the source code for eu.over9000.skadi.io.PersistenceHandler.java

Source

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2014-2015 s1mpl3x <jan[at]over9000.eu>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package eu.over9000.skadi.io;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;

import org.apache.commons.lang3.SystemUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import eu.over9000.skadi.model.StateContainer;

public final class PersistenceHandler {

    private static final Logger LOGGER = LoggerFactory.getLogger(PersistenceHandler.class);

    private static final String PERSISTENCE_DIRECTORY = SystemUtils.USER_HOME + File.separator + ".skadi"
            + File.separator;
    private static final String PERSISTENCE_FILE = "skadi_state.xml";
    private final Object fileLock = new Object();
    private Marshaller marshaller;
    private Unmarshaller unmarshaller;

    public PersistenceHandler() {
        try {
            final JAXBContext context = JAXBContext.newInstance(StateContainer.class);
            this.marshaller = context.createMarshaller();
            this.unmarshaller = context.createUnmarshaller();
            this.marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);

        } catch (final JAXBException e) {
            LOGGER.error("exception construction persistence handler", e);
        }
    }

    public StateContainer loadState() {
        StateContainer result = null;

        try {
            if (Files.exists(this.getStateFilePath())) {
                result = this.readFromFile();
            } else {
                this.checkDir();
                result = new StateContainer();
                this.writeToFile(result);
            }
        } catch (IOException | JAXBException e) {
            LOGGER.error("exception loading state", e);
        }
        return result;
    }

    public void saveState(final StateContainer state) {
        try {
            this.checkDir();
            this.writeToFile(state);
        } catch (IOException | JAXBException e) {
            LOGGER.error("exception saving state", e);
        }
    }

    private Path getStateFilePath() {
        return Paths.get(PERSISTENCE_DIRECTORY, PERSISTENCE_FILE);
    }

    private void writeToFile(final StateContainer state) throws IOException, JAXBException {
        final Path stateFile = this.getStateFilePath();
        synchronized (this.fileLock) {
            this.marshaller.marshal(state, stateFile.toFile());
        }
        LOGGER.debug("wrote state to file");
    }

    private StateContainer readFromFile() throws IOException, JAXBException {
        final Path stateFile = this.getStateFilePath();
        StateContainer state;
        synchronized (this.fileLock) {
            state = (StateContainer) this.unmarshaller.unmarshal(stateFile.toFile());
        }
        LOGGER.debug("load state from file");
        return state;
    }

    private void checkDir() throws IOException {
        Files.createDirectories(Paths.get(PERSISTENCE_DIRECTORY));
    }
}