com.xemantic.tadedon.guava.jar.Manifests.java Source code

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Here is the source code for com.xemantic.tadedon.guava.jar.Manifests.java

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/*
 * Copyright 2010 Xemantic
 *
 * 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 com.xemantic.tadedon.guava.jar;

import static com.google.common.base.Preconditions.checkArgument;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Enumeration;
import java.util.jar.Manifest;

import com.google.common.io.Closeables;

/**
 * Utilities for {@link Manifest} files.
 * <p>
 * Created on Aug 20, 2010
 *
 * @author hshsce
 */
public class Manifests {

    public static final String MANIFEST_RESOURCE = "META-INF/MANIFEST.MF";

    public static final String IMPLEMENTATION_VERSION_PROPERTY = "Implementation-Version";

    public static final String BUILD_NUMBER_PROPERTY = "Build-Number";

    /**
     * @param stringClass
     * @return
     */
    public static Manifest getManifest(Class<?> classFromJarWithManifest) {
        checkArgument(classFromJarWithManifest != null, "classFromJarWithManifest cannot be null");
        ClassLoader classLoader = classFromJarWithManifest.getClassLoader();
        checkArgument(classLoader != null, "classFromJarWithManifest seems to be loaded by bootstrap classloader: "
                + classFromJarWithManifest.getName());
        String classResource = classFromJarWithManifest.getName().replace(".", "/") + ".class";
        URL classUrl = classLoader.getResource(classResource);
        if (classUrl == null) {
            throw new AssertionError("null resource for given class");
        }
        String path = classUrl.getPath();
        int classResourceIndex = path.indexOf(classResource);
        String basePath = path.substring(0, classResourceIndex);
        Manifest manifest = null;
        Enumeration<URL> manifestUrls = getManifestResources(classLoader);
        while (manifestUrls.hasMoreElements()) {
            URL manifestUrl = (URL) manifestUrls.nextElement();
            if (manifestUrl.getPath().startsWith(basePath)) {
                manifest = getManifest(manifestUrl);
                break;

            }
        }
        return manifest;
    }

    public static Enumeration<URL> getManifestResources(ClassLoader classLoader) {
        try {
            return classLoader.getResources(MANIFEST_RESOURCE);
        } catch (IOException e) {
            throw new RuntimeException("Cannot retrieve resources: " + MANIFEST_RESOURCE, e);
        }
    }

    public static Manifest getManifest(URL url) {
        try {
            Manifest manifest = new Manifest();
            boolean threw = true;
            InputStream in = url.openStream();
            try {
                manifest.read(in);
                threw = false;
            } finally {
                Closeables.close(in, threw);
            }
            return manifest;
        } catch (IOException e) {
            throw new RuntimeException("Cannot read manifest file from given URL", e);
        }
    }

    public static String getVersion(Class<?> classFromJarWithManifest) {
        checkArgument(classFromJarWithManifest != null, "manifest cannot be null");
        return getVersion(classFromJarWithManifest);
    }

    public static String getVersion(Manifest manifest) {
        checkArgument(manifest != null, "manifest cannot be null");
        return manifest.getMainAttributes().getValue(IMPLEMENTATION_VERSION_PROPERTY);
    }

    public static String getBuildNumber(Class<?> classFromJarWithManifest) {
        checkArgument(classFromJarWithManifest != null, "classFromJarWithManifest cannot be null");
        return getBuildNumber(getManifest(classFromJarWithManifest));
    }

    public static String getBuildNumber(Manifest manifest) {
        checkArgument(manifest != null, "manifest cannot be null");
        return manifest.getMainAttributes().getValue(BUILD_NUMBER_PROPERTY);
    }

    public static String getFullVersion(Class<?> classFromJarWithManifest) {
        checkArgument(classFromJarWithManifest != null, "classFromJarWithManifest cannot be null");
        Manifest manifest = getManifest(classFromJarWithManifest);
        if (manifest == null) {
            return null;
        }
        return getFullVersion(manifest);
    }

    public static String getFullVersion(Manifest manifest) {
        String version = getVersion(manifest);
        if (version == null) {
            return null;
        }
        String buildNumber = getBuildNumber(manifest);
        if (buildNumber != null) {
            version += "-";
            version += buildNumber;
        }
        return version;
    }

}