io.joshworks.snappy.maven.tools.JvmUtils Maven / Gradle / Ivy

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/*
 * Copyright 2012-2014 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
 *
 *      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 io.joshworks.snappy.maven.tools;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;

/**
 * Java Virtual Machine Utils.
 *
 * @author Phillip Webb
 */
abstract class JvmUtils {

    /**
     * Various search locations for tools, including the odd Java 6 OSX jar.
     */
    private static final String[] TOOLS_LOCATIONS = {"lib/tools.jar", "../lib/tools.jar",
            "../Classes/classes.jar"};

    public static ClassLoader getToolsClassLoader() {
        ClassLoader systemClassLoader = ClassLoader.getSystemClassLoader();
        return new URLClassLoader(new URL[]{getToolsJarUrl()}, systemClassLoader);
    }

    public static URL getToolsJarUrl() {
        String javaHome = getJavaHome();
        for (String location : TOOLS_LOCATIONS) {
            try {
                URL url = new URL(javaHome + "/" + location);
                if (new File(url.toURI()).exists()) {
                    return url;
                }
            } catch (Exception ex) {
                // Ignore and try the next location
            }
        }
        throw new IllegalStateException("Unable to locate tools.jar");
    }

    private static String getJavaHome() {
        try {
            return new File(System.getProperty("java.home")).toURI().toURL()
                    .toExternalForm();
        } catch (MalformedURLException e) {
            throw new IllegalStateException("Cannot locate java.home", e);
        }
    }

}