Эфир, чтобы получить артефакт из хранилища во время выполнения

Question

Это пример кода, который я взял из примеров кодов эфира, чтобы получить артефакт.

public class Main2 {
    public static void main(String[] args) throws Exception {
        DefaultServiceLocator locator = new DefaultServiceLocator();
        locator.addService(RepositoryConnectorFactory.class, FileRepositoryConnectorFactory.class);
        locator.addService(RepositoryConnectorFactory.class, WagonRepositoryConnectorFactory.class);
        locator.addService(VersionResolver.class, DefaultVersionResolver.class);
        locator.addService(VersionRangeResolver.class, DefaultVersionRangeResolver.class);
        locator.addService(ArtifactDescriptorReader.class, DefaultArtifactDescriptorReader.class);
        locator.setServices(WagonProvider.class, new WagonProvider() {
            public Wagon lookup(String roleHint) throws Exception {
                if ("http".equals(roleHint)) {
                    return new LightweightHttpWagon();
                }
                return null;
            }

            public void release(Wagon wagon) {
            }
        });

        RepositorySystem system = locator.getService(RepositorySystem.class);

        MavenRepositorySystemSession session = new MavenRepositorySystemSession();

        LocalRepository localRepo = new LocalRepository("target/local-repo");
        session.setLocalRepositoryManager(system.newLocalRepositoryManager(localRepo));

        Artifact artifact = new DefaultArtifact("com.hazelcast:hazelcast:LATEST");

        RemoteRepository repo = new RemoteRepository("central", "default", "http://repo1.maven.org/maven2/");

        ArtifactRequest artifactRequest = new ArtifactRequest();
        artifactRequest.setArtifact(artifact);
        artifactRequest.addRepository(repo);

        ArtifactResult artifactResult = system.resolveArtifact(session, artifactRequest);

        artifact = artifactResult.getArtifact();

        System.out.println(artifact + " resolved to  " + artifact.getFile());
    }
}

Этот код предназначен для извлечения артефакта из maven central, но он выдает эту ошибку:

Exception in thread "main" org.sonatype.aether.resolution.ArtifactResolutionException: Could not transfer artifact com.hazelcast:hazelcast:jar:3.4.1 from/to central (http://repo1.maven.org/maven2/): NullPointerException
    at org.sonatype.aether.impl.internal.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:541)
    at org.sonatype.aether.impl.internal.DefaultArtifactResolver.resolveArtifacts(DefaultArtifactResolver.java:220)
    at org.sonatype.aether.impl.internal.DefaultArtifactResolver.resolveArtifact(DefaultArtifactResolver.java:197)
    at org.sonatype.aether.impl.internal.DefaultRepositorySystem.resolveArtifact(DefaultRepositorySystem.java:323)
    at maven.test.poc1.Main2.main(Main2.java:69)
Caused by: org.sonatype.aether.transfer.ArtifactTransferException: Could not transfer artifact com.hazelcast:hazelcast:jar:3.4.1 from/to central (http://repo1.maven.org/maven2/): NullPointerException
    at org.sonatype.aether.connector.wagon.WagonRepositoryConnector$4.wrap(WagonRepositoryConnector.java:951)
    at org.sonatype.aether.connector.wagon.WagonRepositoryConnector$4.wrap(WagonRepositoryConnector.java:941)
    at org.sonatype.aether.connector.wagon.WagonRepositoryConnector$GetTask.run(WagonRepositoryConnector.java:669)
    at org.sonatype.aether.util.concurrency.RunnableErrorForwarder$1.run(RunnableErrorForwarder.java:60)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
    at org.apache.maven.wagon.providers.http.LightweightHttpWagon.openConnectionInternal(LightweightHttpWagon.java:266)
    at org.apache.maven.wagon.AbstractWagon.openConnection(AbstractWagon.java:105)
    at org.apache.maven.wagon.AbstractWagon.connect(AbstractWagon.java:207)
    at org.sonatype.aether.connector.wagon.WagonRepositoryConnector.connectWagon(WagonRepositoryConnector.java:345)
    at org.sonatype.aether.connector.wagon.WagonRepositoryConnector.pollWagon(WagonRepositoryConnector.java:385)
    at org.sonatype.aether.connector.wagon.WagonRepositoryConnector$GetTask.run(WagonRepositoryConnector.java:571)
    ... 4 more

Пожалуйста, кто-нибудь подскажет, какие изменения должны быть там. Это пример кода, который я взял из примера кода эфира.

Answer 1

Это общая проблема с последней версией (1.13.1) org.apache.maven.wagon:wagon-http-lightweight. При использовании с последней версией других зависимостей эфира и maven выдает ошибку.

Так что не используйте последнюю версию, используйте старую версию. Это те зависимости, которые я использовал, которые работали для меня вместе с кодом, упомянутым в моем вопросе.

    <dependency>
        <groupId>org.sonatype.aether</groupId>
        <artifactId>aether-util</artifactId>
        <version>1.13.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-aether-provider</artifactId>
        <version>3.0.3</version>
    </dependency>
    <dependency>
        <groupId>org.sonatype.aether</groupId>
        <artifactId>aether-connector-file</artifactId>
        <version>1.13.1</version>
    </dependency>
    <dependency>
        <groupId>org.sonatype.aether</groupId>
        <artifactId>aether-connector-wagon</artifactId>
        <version>1.13.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven.wagon</groupId>
        <artifactId>wagon-http-lightweight</artifactId>
        <version>1.0</version>
    </dependency>

и код для загрузки артефакта из хранилища, как указано ниже

public class Main2 {
    public static void main(String[] args) throws Exception {
        DefaultServiceLocator locator = new DefaultServiceLocator();
        locator.addService(RepositoryConnectorFactory.class, FileRepositoryConnectorFactory.class);
        locator.addService(RepositoryConnectorFactory.class, WagonRepositoryConnectorFactory.class);
        locator.addService(VersionResolver.class, DefaultVersionResolver.class);
        locator.addService(VersionRangeResolver.class, DefaultVersionRangeResolver.class);
        locator.addService(ArtifactDescriptorReader.class, DefaultArtifactDescriptorReader.class);
        locator.setServices(WagonProvider.class, new WagonProvider() {
            public Wagon lookup(String roleHint) throws Exception {
                if ("http".equals(roleHint)) {
                    return new LightweightHttpWagon();
                }
                return null;
            }

            public void release(Wagon wagon) {
            }
        });

        RepositorySystem system = locator.getService(RepositorySystem.class);

        MavenRepositorySystemSession session = new MavenRepositorySystemSession();

        LocalRepository localRepo = new LocalRepository("target/local-repo");
        session.setLocalRepositoryManager(system.newLocalRepositoryManager(localRepo));

        Artifact artifact = new DefaultArtifact("com.hazelcast:hazelcast:LATEST");

        RemoteRepository repo = new RemoteRepository("central", "default", "http://repo1.maven.org/maven2/");

        ArtifactRequest artifactRequest = new ArtifactRequest();
        artifactRequest.setArtifact(artifact);
        artifactRequest.addRepository(repo);

        ArtifactResult artifactResult = system.resolveArtifact(session, artifactRequest);

        artifact = artifactResult.getArtifact();

        System.out.println(artifact + " resolved to  " + artifact.getFile());
    }
}