org.springframework.boot.gradle.util.VersionExtractor Maven / Gradle / Ivy
/*
* Copyright 2012-2020 the original author or authors.
*
* 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
*
* https://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.springframework.boot.gradle.util;
import java.io.File;
import java.io.IOException;
import java.net.JarURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.jar.Attributes;
import java.util.jar.JarFile;
/**
* Extracts version information for a Class.
*
* @author Andy Wilkinson
* @author Scott Frederick
* @since 2.3.0
*/
public final class VersionExtractor {
private VersionExtractor() {
}
/**
* Return the version information for the provided {@link Class}.
* @param cls the Class to retrieve the version for
* @return the version, or {@code null} if a version can not be extracted
*/
public static String forClass(Class cls) {
String implementationVersion = cls.getPackage().getImplementationVersion();
if (implementationVersion != null) {
return implementationVersion;
}
URL codeSourceLocation = cls.getProtectionDomain().getCodeSource().getLocation();
try {
URLConnection connection = codeSourceLocation.openConnection();
if (connection instanceof JarURLConnection) {
return getImplementationVersion(((JarURLConnection) connection).getJarFile());
}
try (JarFile jarFile = new JarFile(new File(codeSourceLocation.toURI()))) {
return getImplementationVersion(jarFile);
}
}
catch (Exception ex) {
return null;
}
}
private static String getImplementationVersion(JarFile jarFile) throws IOException {
return jarFile.getManifest().getMainAttributes().getValue(Attributes.Name.IMPLEMENTATION_VERSION);
}
}