在 Java 程序中从 Maven 存储库下载工件

Question

我需要编写从给定 Maven 存储库下载给定工件 (GAV) 的 Java 代码。过去我使用了 Nexus 2 的 REST 接口（这很容易），但我想要一些独立于所使用的存储库（Nexus 2、Nexus 3、Artifactory）的东西。

在Fetching Maven artifacts programmatically 中提出了类似的问题，但主要答案来自 2014 年，并建议自 2014 年以来未更新的库。

Answer 1

可以使用 Aether（版本 1.1.0）做以下事情：

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import org.apache.maven.repository.internal.MavenRepositorySystemUtils;
import org.eclipse.aether.DefaultRepositorySystemSession;
import org.eclipse.aether.RepositorySystem;
import org.eclipse.aether.RepositorySystemSession;
import org.eclipse.aether.artifact.Artifact;
import org.eclipse.aether.artifact.DefaultArtifact;
import org.eclipse.aether.connector.basic.BasicRepositoryConnectorFactory;
import org.eclipse.aether.impl.DefaultServiceLocator;
import org.eclipse.aether.repository.LocalRepository;
import org.eclipse.aether.repository.RemoteRepository;
import org.eclipse.aether.resolution.ArtifactRequest;
import org.eclipse.aether.resolution.ArtifactResolutionException;
import org.eclipse.aether.resolution.ArtifactResult;
import org.eclipse.aether.spi.connector.RepositoryConnectorFactory;
import org.eclipse.aether.spi.connector.transport.TransporterFactory;
import org.eclipse.aether.transport.file.FileTransporterFactory;
import org.eclipse.aether.transport.http.HttpTransporterFactory;


public class ArtifactDownload
{

  private static RepositorySystem newRepositorySystem()
  {
    DefaultServiceLocator locator = MavenRepositorySystemUtils
        .newServiceLocator();
    locator.addService(RepositoryConnectorFactory.class,
        BasicRepositoryConnectorFactory.class);
    locator.addService(TransporterFactory.class, FileTransporterFactory.class);
    locator.addService(TransporterFactory.class, HttpTransporterFactory.class);
    return locator.getService(RepositorySystem.class);

  }

  private static RepositorySystemSession newSession(RepositorySystem system,
      File localRepository)
  {
    DefaultRepositorySystemSession session = MavenRepositorySystemUtils
        .newSession();
    LocalRepository localRepo = new LocalRepository(localRepository.toString());
    session.setLocalRepositoryManager(system.newLocalRepositoryManager(session,
        localRepo));
    return session;
  }


  public static File getArtifactByAether(String groupId, String artifactId,
      String version, String classifier, String packaging, File localRepository)
      throws IOException
  {
    RepositorySystem repositorySystem = newRepositorySystem();
    RepositorySystemSession session = newSession(repositorySystem,
        localRepository);

    Artifact artifact = new DefaultArtifact(groupId, artifactId, classifier,
        packaging, version);
    ArtifactRequest artifactRequest = new ArtifactRequest();
    artifactRequest.setArtifact(artifact);

    List<RemoteRepository> repositories = new ArrayList<>();

    RemoteRepository remoteRepository = new RemoteRepository.Builder("public",
        "default", "http://somerepo").build();

    repositories.add(remoteRepository);

    artifactRequest.setRepositories(repositories);
    File result;

    try
    {
      ArtifactResult artifactResult = repositorySystem.resolveArtifact(session,
          artifactRequest);
      artifact = artifactResult.getArtifact();
      if (artifact != null)
      {
        result = artifact.getFile();
      }
      else
      {
        result = null;
      }
    }
    catch (ArtifactResolutionException e)
    {
      throw new IOException("Artefakt " + groupId + ":" + artifactId + ":"
          + version + " konnte nicht heruntergeladen werden.");
    }

    return result;

  }
}

使用以下工件

    <dependency>
      <groupId>org.eclipse.aether</groupId>
      <artifactId>aether-api</artifactId>
      <version>${aetherVersion}</version>
    </dependency>
    <dependency>
      <groupId>org.eclipse.aether</groupId>
      <artifactId>aether-spi</artifactId>
      <version>${aetherVersion}</version>
    </dependency>
    <dependency>
      <groupId>org.eclipse.aether</groupId>
      <artifactId>aether-impl</artifactId>
      <version>${aetherVersion}</version>
    </dependency>
    <dependency>
      <groupId>org.eclipse.aether</groupId>
      <artifactId>aether-connector-basic</artifactId>
      <version>${aetherVersion}</version>
    </dependency>
    <dependency>
      <groupId>org.eclipse.aether</groupId>
      <artifactId>aether-transport-file</artifactId>
      <version>${aetherVersion}</version>
    </dependency>
    <dependency>
      <groupId>org.eclipse.aether</groupId>
      <artifactId>aether-transport-http</artifactId>
      <version>${aetherVersion}</version>
    </dependency>
    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-aether-provider</artifactId>
      <version>${mavenVersion}</version>
    </dependency>

和

<aetherVersion>1.1.0</aetherVersion>
<mavenVersion>3.3.3</mavenVersion>