tools/hivemall-docs/src/main/java/hivemall/docs/IncludeProjectDependenciesComponentConfigurator.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.
 */
package hivemall.docs;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import javax.annotation.Nonnull;

import org.codehaus.classworlds.ClassRealm;
import org.codehaus.plexus.component.annotations.Component;
import org.codehaus.plexus.component.configurator.AbstractComponentConfigurator;
import org.codehaus.plexus.component.configurator.ComponentConfigurationException;
import org.codehaus.plexus.component.configurator.ConfigurationListener;
import org.codehaus.plexus.component.configurator.converters.composite.ObjectWithFieldsConverter;
import org.codehaus.plexus.component.configurator.converters.special.ClassRealmConverter;
import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluationException;
import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluator;
import org.codehaus.plexus.configuration.PlexusConfiguration;

/**
 * A custom ComponentConfigurator which adds the project's runtime classpath elements to the MOJO
 * classloader.
 */
@SuppressWarnings("deprecation")
@Component(role = org.codehaus.plexus.component.configurator.ComponentConfigurator.class,
        hint = "include-project-dependencies")
public class IncludeProjectDependenciesComponentConfigurator extends AbstractComponentConfigurator {

    public void configureComponent(final Object component, final PlexusConfiguration configuration,
            final ExpressionEvaluator expressionEvaluator, final ClassRealm containerRealm,
            final ConfigurationListener listener) throws ComponentConfigurationException {
        addProjectDependenciesToClassRealm(expressionEvaluator, containerRealm);

        converterLookup.registerConverter(new ClassRealmConverter(containerRealm));

        ObjectWithFieldsConverter converter = new ObjectWithFieldsConverter();

        converter.processConfiguration(converterLookup, component, containerRealm.getClassLoader(),
            configuration, expressionEvaluator, listener);
    }

    @SuppressWarnings("unchecked")
    private static void addProjectDependenciesToClassRealm(
            final ExpressionEvaluator expressionEvaluator, final ClassRealm containerRealm)
            throws ComponentConfigurationException {
        final List<String> runtimeClasspathElements;
        try {
            // noinspection unchecked
            runtimeClasspathElements = (List<String>) expressionEvaluator.evaluate(
                "${project.runtimeClasspathElements}");
        } catch (ExpressionEvaluationException e) {
            throw new ComponentConfigurationException(
                "There was a problem evaluating: ${project.runtimeClasspathElements}", e);
        }

        // Add the project dependencies to the ClassRealm
        final URL[] urls = buildURLs(runtimeClasspathElements);
        for (URL url : urls) {
            containerRealm.addConstituent(url);
        }
    }

    @Nonnull
    private static URL[] buildURLs(@Nonnull final List<String> runtimeClasspathElements)
            throws ComponentConfigurationException {
        // Add the projects classes and dependencies
        final List<URL> urls = new ArrayList<>(runtimeClasspathElements.size());
        for (String element : runtimeClasspathElements) {
            try {
                URL url = new File(element).toURI().toURL();
                urls.add(url);
            } catch (MalformedURLException e) {
                throw new ComponentConfigurationException(
                    "Unable to access project dependency: " + element, e);
            }
        }
        return urls.toArray(new URL[urls.size()]);
    }

}