savant.util.Version.java Source code

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Here is the source code for savant.util.Version.java

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/**
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.
 *
 * This 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 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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 along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package savant.util;

import java.io.IOException;
import java.net.URL;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 *
 * @author mfiume, tarkvara
 */
public class Version implements Comparable {
    private static final Log LOG = LogFactory.getLog(Version.class);

    int major;
    int minor;
    int revision;

    /**
     * Construct a version directly from a string of the form <i>major</i>.<i>minor</i>.<i>revision</i>.
     * @param versionString
     */
    public Version(String versionString) {
        String[] pieces = versionString.split("\\.");
        if (pieces.length != 3) {
            throw new IllegalArgumentException(String.format("{0} is not a valid version number.", versionString));
        }
        major = Integer.parseInt(pieces[0]);
        minor = Integer.parseInt(pieces[1]);
        revision = Integer.parseInt(pieces[2]);
    }

    /**
     * Factory method which construct a Version object from a URL pointing to an XML file.
     * @param url URL of our version.xml file
     * @return the version number read from the file
     */
    public static Version fromURL(URL url) throws IOException {
        try {
            XMLStreamReader reader = XMLInputFactory.newInstance()
                    .createXMLStreamReader(NetworkUtils.openStream(url));
            boolean done = false;
            boolean foundCurrentVersion = false;
            do {
                switch (reader.next()) {
                case XMLStreamConstants.START_ELEMENT:
                    String elemName = reader.getLocalName();
                    if (elemName.equals("version")
                            && "current_release".equals(reader.getAttributeValue(null, "status"))) {
                        foundCurrentVersion = true;
                    } else if (foundCurrentVersion && elemName.equals("name")) {
                        return new Version(reader.getElementText());
                    } else {
                        foundCurrentVersion = false;
                    }
                    break;
                case XMLStreamConstants.END_DOCUMENT:
                    reader.close();
                    done = true;
                    break;
                }
            } while (!done);
        } catch (XMLStreamException x) {
            throw new IOException("Unable to get version number from web-site.", x);
        }
        return null;
    }

    @Override
    public int compareTo(Object o) {
        if (o instanceof Version) {
            Version v1 = this;
            Version v2 = (Version) o;

            if (v1.major > v2.major) {
                return 1;
            } else if (v1.major < v2.major) {
                return -1;
            }

            if (v1.minor > v2.minor) {
                return 1;
            } else if (v1.minor < v2.minor) {
                return -1;
            }

            if (v1.revision > v2.revision) {
                return 1;
            } else if (v1.revision < v2.revision) {
                return -1;
            }

            return 0;
        }

        return 1;
    }

    @Override
    public String toString() {
        return major + "." + minor + "." + revision;
    }
}