VersionMain.java

/*
 * Copyright 2011 ZerothAngel <zerothangel@tyrannyofheaven.org>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * 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 org.tyrannyofheaven.bukkit.util;

import java.io.IOException;
import java.net.URL;
import java.security.CodeSource;
import java.util.jar.JarInputStream;

/**
 * Locates our JAR file and outputs a few fields from its manifest.
 * 
 * @author zerothangel
 */
public class VersionMain {

    public static void main(String[] args) throws IOException {
        VersionInfo versionInfo = getVersion(VersionMain.class);
        if (versionInfo != null) {
            System.out.println(versionInfo.getFullVersion());
        }
        else {
            System.err.println("Unable to find my jar file!");
            System.exit(1);
        }
    }

    // Retrieve artifactId, version, build from manifest
    static VersionInfo getVersion(Class<?> clazz) throws IOException {
        CodeSource codeSource = clazz.getProtectionDomain().getCodeSource();
        URL url = codeSource.getLocation();
        if (url.toExternalForm().toLowerCase().endsWith(".jar")) { // Hmmm
            JarInputStream jis = new JarInputStream(url.openStream());
            try {
                String artifactId = jis.getManifest().getMainAttributes().getValue("Implementation-Title");
                String version = jis.getManifest().getMainAttributes().getValue("Implementation-Version");
                String build = jis.getManifest().getMainAttributes().getValue("Implementation-Build");
                return new VersionInfo(artifactId, version, build);
            }
            finally {
                jis.close();
            }
        }
        else {
            return null;
        }
    }

}