.mvn/wrapper/MavenWrapperDownloader.java

/*
 * 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.
 */

import java.io.IOException;
import java.io.InputStream;
import java.net.Authenticator;
import java.net.PasswordAuthentication;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.LinkOption;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.nio.file.StandardOpenOption;
import java.util.Properties;

public final class MavenWrapperDownloader {
    private static final String WRAPPER_VERSION = "3.1.1";

    private static final boolean VERBOSE = Boolean.parseBoolean(System.getenv("MVNW_VERBOSE"));

    /**
     * Default URL to download the maven-wrapper.jar from, if no 'downloadUrl' is provided.
     */
    private static final String DEFAULT_DOWNLOAD_URL =
            "https://repo.maven.apache.org/maven2/org/apache/maven/wrapper/maven-wrapper/" + WRAPPER_VERSION
                    + "/maven-wrapper-" + WRAPPER_VERSION + ".jar";

    /**
     * Path to the maven-wrapper.properties file, which might contain a downloadUrl property to use instead of the
     * default one.
     */
    private static final String MAVEN_WRAPPER_PROPERTIES_PATH = ".mvn/wrapper/maven-wrapper.properties";

    /**
     * Path where the maven-wrapper.jar will be saved to.
     */
    private static final String MAVEN_WRAPPER_JAR_PATH = ".mvn/wrapper/maven-wrapper.jar";

    /**
     * Name of the property which should be used to override the default download url for the wrapper.
     */
    private static final String PROPERTY_NAME_WRAPPER_URL = "wrapperUrl";

    public static void main(String[] args) {
        if (args.length == 0) {
            System.err.println(" - ERROR projectBasedir parameter missing");
            System.exit(1);
        }

        log(" - Downloader started");
        final String dir = args[0].replace("..", ""); // Sanitize path
        final Path projectBasedir = Paths.get(dir).toAbsolutePath().normalize();
        if (!Files.isDirectory(projectBasedir, LinkOption.NOFOLLOW_LINKS)) {
            System.err.println(" - ERROR projectBasedir not exists: " + projectBasedir);
            System.exit(1);
        }

        log(" - Using base directory: " + projectBasedir);

        // If the maven-wrapper.properties exists, read it and check if it contains a custom
        // wrapperUrl parameter.
        Path mavenWrapperPropertyFile = projectBasedir.resolve(MAVEN_WRAPPER_PROPERTIES_PATH);
        String url = readWrapperUrl(mavenWrapperPropertyFile);

        try {
            Path outputFile = projectBasedir.resolve(MAVEN_WRAPPER_JAR_PATH);
            createDirectories(outputFile.getParent());
            downloadFileFromURL(url, outputFile);
            log("Done");
            System.exit(0);
        } catch (IOException e) {
            System.err.println("- Error downloading");
            e.printStackTrace();
            System.exit(1);
        }
    }

    private static void downloadFileFromURL(String urlString, Path destination) throws IOException {
        log(" - Downloading to: " + destination);
        if (System.getenv("MVNW_USERNAME") != null && System.getenv("MVNW_PASSWORD") != null) {
            final String username = System.getenv("MVNW_USERNAME");
            final char[] password = System.getenv("MVNW_PASSWORD").toCharArray();
            Authenticator.setDefault(new Authenticator() {
                @Override
                protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication(username, password);
                }
            });
        }
        URL website = new URL(urlString);
        try (InputStream inStream = website.openStream()) {
            Files.copy(inStream, destination, StandardCopyOption.REPLACE_EXISTING);
        }
        log(" - Downloader complete");
    }

    private static void createDirectories(Path outputPath) throws IOException {
        if (!Files.isDirectory(outputPath, LinkOption.NOFOLLOW_LINKS)) {
            Path createDirectories = Files.createDirectories(outputPath);
            log(" - Directories created: " + createDirectories);
        }
    }

    private static String readWrapperUrl(Path mavenWrapperPropertyFile) {
        String url = DEFAULT_DOWNLOAD_URL;
        if (Files.exists(mavenWrapperPropertyFile, LinkOption.NOFOLLOW_LINKS)) {
            log(" - Reading property file: " + mavenWrapperPropertyFile);
            try (InputStream in = Files.newInputStream(mavenWrapperPropertyFile, StandardOpenOption.READ)) {
                Properties mavenWrapperProperties = new Properties();
                mavenWrapperProperties.load(in);
                url = mavenWrapperProperties.getProperty(PROPERTY_NAME_WRAPPER_URL, DEFAULT_DOWNLOAD_URL);
            } catch (IOException e) {
                System.err.println(" - ERROR loading '" + MAVEN_WRAPPER_PROPERTIES_PATH + "'");
            }
        }
        log(" - Downloading from: " + url);
        return url;
    }

    private static void log(String msg) {
        if (VERBOSE) {
            System.out.println(msg);
        }
    }

}