VersionUtils.java

package org.peerbox.utils;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

import net.tomp2p.p2p.Peer;

import org.hive2hive.core.api.H2HNode;
import org.peerbox.App;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * VersionUtils allows extracting version information of some important dependencies.
 * It reads the pom.properties file generated by maven in the jar package.
 * A consequence of this is that it only works if jar packages are executed
 * (e.g. it does not work in eclipse projects when a regular run configuration is run).
 *
 * @author albrecht
 *
 */
public class VersionUtils {

	private static final Logger logger = LoggerFactory.getLogger(VersionUtils.class);

	private VersionUtils() {
		// prevent instances
	}

	/**
	 * reads the version property from the property file.
	 *
	 * @param clazz a class in the package (note: must be part of the artifact).
	 * @param pomProperties resource path to the pom.properties file inside the jar.
	 * @return the version string or null if it was not possible to read.
	 */
	private static synchronized String readVersionFromPom(Class<?> clazz, String pomProperties) {
		String version = null;

		// try reading the pom.properties file from the jar
		try {
			Properties p = new Properties();
			try (InputStream is = clazz.getResourceAsStream(pomProperties)) {
				if (is != null) {
					p.load(is);
					version = p.getProperty("version", null);
				}
			}
		} catch (IOException e) {
			version = null;
			logger.warn("Could not read version for '{}' from file '{}'",
					clazz.getName(), pomProperties);
		}

		// using Java API
		if (version == null) {
			Package p = clazz.getPackage();
			if (p != null) {
				version = p.getImplementationVersion();
				if (version == null) {
					version = p.getSpecificationVersion();
				}
			}
		}

		return version;
	}

	/**
	 * Get version of PeerWasp.
	 *
	 * @return peerwasp version string or null.
	 */
	public static String getPeerWaspVersion() {
		String pomProperties = "/META-INF/maven/com.peerwasp/peerwasp/pom.properties";
		Class<App> clazz = App.class;
		String version = readVersionFromPom(clazz, pomProperties);
		return version;
	}

	/**
	 * Get version of Hive2Hive.
	 *
	 * @return h2h version string (core) or null.
	 */
	public static String getH2HVersion() {
		String pomProperties = "/META-INF/maven/org.hive2hive/org.hive2hive.core/pom.properties";
		Class<H2HNode> clazz = H2HNode.class;
		String version = readVersionFromPom(clazz, pomProperties);
		return version;
	}

	/**
	 * Get version of TomP2P.
	 *
	 * @return tomp2p version string (core) or null.
	 */
	public static String getTomP2PVersion() {
		String pomProperties = "/META-INF/maven/net.tomp2p/tomp2p-core/pom.properties";
		Class<Peer> clazz = Peer.class;
		String version = readVersionFromPom(clazz, pomProperties);
		return version;
	}

}