WagonExcluder.java

package org.apache.maven.plugin.internal;

/*
 * 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 org.sonatype.aether.artifact.Artifact;
import org.sonatype.aether.collection.DependencyCollectionContext;
import org.sonatype.aether.collection.DependencySelector;
import org.sonatype.aether.graph.Dependency;

/**
 * Assists in detecting wagon providers brought into the plugin class path via legacy Maven core artifacts (e.g.
 * maven-core:2.0.6) and excluding them. A plugin should be able to explicitly declare dependencies on specific wagons
 * for its use. However, the (old) wagons pulled in transitively via legacy Maven core artifacts are usually not
 * intended as dependencies and more importantly screw up artifact resolution because they would get preferred over the
 * core wagon versions. This is a hack to provide backward-compat with Maven 2 (MNG-4528, MNG-4561).
 * 
 * @author Benjamin Bentmann
 */
class WagonExcluder
    implements DependencySelector
{

    private final boolean coreArtifact;

    public WagonExcluder()
    {
        this( false );
    }

    private WagonExcluder( boolean coreArtifact )
    {
        this.coreArtifact = coreArtifact;
    }

    public boolean selectDependency( Dependency dependency )
    {
        return !coreArtifact || !isWagonProvider( dependency.getArtifact() );
    }

    public DependencySelector deriveChildSelector( DependencyCollectionContext context )
    {
        if ( coreArtifact || !isLegacyCoreArtifact( context.getDependency().getArtifact() ) )
        {
            return this;
        }
        else
        {
            return new WagonExcluder( true );
        }
    }

    private boolean isLegacyCoreArtifact( Artifact artifact )
    {
        String version = artifact.getVersion();
        return version != null && version.startsWith( "2." ) && artifact.getArtifactId().startsWith( "maven-" )
            && artifact.getGroupId().equals( "org.apache.maven" );
    }

    private boolean isWagonProvider( Artifact artifact )
    {
        if ( "org.apache.maven.wagon".equals( artifact.getGroupId() ) )
        {
            return artifact.getArtifactId().startsWith( "wagon-" );
        }
        return false;
    }

    @Override
    public boolean equals( Object obj )
    {
        if ( obj == this )
        {
            return true;
        }
        else if ( obj == null || !getClass().equals( obj.getClass() ) )
        {
            return false;
        }

        WagonExcluder that = (WagonExcluder) obj;
        return coreArtifact == that.coreArtifact;
    }

    @Override
    public int hashCode()
    {
        int hash = getClass().hashCode();
        hash = hash * 31 + ( coreArtifact ? 1 : 0 );
        return hash;
    }

}