org.apache.maven.wrapper.BootstrapMainStarter Maven / Gradle / Ivy

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Maven Wrapper Jar download, installs and launches installed target Maven distribution as part of Maven Wrapper scripts run.

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.maven.wrapper;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import java.nio.file.DirectoryStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Iterator;
import java.util.Locale;

/**
 * Maven starter, from a provided Maven home directory.
 *
 * @author Hans Dockter
 */
public class BootstrapMainStarter {
    public void start(String[] args, Path mavenHome) throws Exception {
        final Path mavenJar = findLauncherJar(mavenHome);
        URLClassLoader contextClassLoader = new URLClassLoader(
                new URL[] {mavenJar.toUri().toURL()},
                ClassLoader.getSystemClassLoader().getParent());
        Thread.currentThread().setContextClassLoader(contextClassLoader);
        Class mainClass = contextClassLoader.loadClass("org.codehaus.plexus.classworlds.launcher.Launcher");

        System.setProperty("maven.home", mavenHome.toAbsolutePath().toString());
        System.setProperty(
                "classworlds.conf",
                mavenHome.resolve("bin/m2.conf").toAbsolutePath().toString());

        Method mainMethod = mainClass.getMethod("main", String[].class);
        mainMethod.invoke(null, new Object[] {args});
    }

    private Path findLauncherJar(Path mavenHome) throws IOException {
        final Path mavenBoot = mavenHome.resolve("boot");
        if (Files.isDirectory(mavenBoot)) {
            try (DirectoryStream ds = Files.newDirectoryStream(mavenBoot, "plexus-classworlds-*.jar")) {
                Iterator iterator = ds.iterator();
                if (iterator.hasNext()) {
                    return iterator.next();
                }
            }
        }
        throw new FileNotFoundException(String.format(
                Locale.ROOT, "Could not locate the Maven launcher JAR" + " in Maven distribution '%s'.", mavenHome));
    }
}