core-it-support/core-it-plugins/maven-it-plugin-uses-wagon/src/main/java/org/apache/maven/plugin/coreit/LoadResourceMojo.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 org.apache.maven.plugin.coreit;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URL;
import java.util.Collections;
import java.util.List;
import java.util.Properties;

import org.apache.maven.artifact.manager.WagonManager;
import org.apache.maven.plugin.AbstractMojo;
import org.apache.maven.plugin.MojoExecutionException;
import org.apache.maven.plugin.MojoFailureException;
import org.apache.maven.plugins.annotations.Component;
import org.apache.maven.plugins.annotations.LifecyclePhase;
import org.apache.maven.plugins.annotations.Mojo;
import org.apache.maven.plugins.annotations.Parameter;
import org.apache.maven.wagon.repository.Repository;

/**
 * Loads resources from a class loader used to load a wagon provider. The wagon is merely used to access the extension
 * class loader it came from which is otherwise not accessible to a plugin.
 *
 * @author Benjamin Bentmann
 */
@Mojo(name = "load-resource", defaultPhase = LifecyclePhase.VALIDATE)
public class LoadResourceMojo extends AbstractMojo {

    /**
     * The Wagon manager used to retrieve wagon providers.
     */
    @Component
    private WagonManager wagonManager;

    /**
     * The path to the properties file used to track the results of the resource loading via the wagon's class loader.
     */
    @Parameter(property = "wagon.wagonClassLoaderOutput")
    private File wagonClassLoaderOutput;

    /**
     * The role hint for the wagon provider to load. The class loader of this provider will be used to load the
     * resources.
     */
    @Parameter(property = "wagon.wagonProtocol")
    private String wagonProtocol;

    /**
     * The repository to load the wagon for, if applicable.
     */
    @Parameter(property = "wagon.repositoryId")
    private String repositoryId;

    /**
     * The set of resources to load. For each specified absolute resource path <code>ARP</code> that was successfully
     * loaded, the generated properties files will contain a key named <code>ARP</code> whose value gives the URL to the
     * resource. In addition, the keys <code>ARP.count</code>, <code>ARP.0</code>, <code>ARP.1</code> etc. will
     * enumerate all URLs matching the resource name.
     */
    @Parameter
    private String[] resourcePaths;

    /**
     * Runs this mojo.
     *
     * @throws MojoFailureException If the attached file has not been set.
     */
    public void execute() throws MojoExecutionException, MojoFailureException {
        getLog().info("[MAVEN-CORE-IT-LOG] Looking up wagon for protocol " + wagonProtocol);

        Object wagon;
        try {
            if (repositoryId != null) {
                wagon = wagonManager.getWagon(new Repository(repositoryId, wagonProtocol + "://host/path"));
            } else {
                wagon = wagonManager.getWagon(wagonProtocol);
            }
        } catch (Exception e) {
            throw new MojoExecutionException("Failed to load wagon for protocol " + wagonProtocol, e);
        }

        ClassLoader classLoader = wagon.getClass().getClassLoader();

        getLog().info("[MAVEN-CORE-IT-LOG] Using class loader " + classLoader);

        Properties loaderProperties = new Properties();
        loaderProperties.setProperty("wagon.class", wagon.getClass().getName());

        if (resourcePaths != null) {
            for (String path : resourcePaths) {
                getLog().info("[MAVEN-CORE-IT-LOG] Loading resource " + path);

                URL url = classLoader.getResource(path);
                getLog().info("[MAVEN-CORE-IT-LOG]   Loaded resource from " + url);
                if (url != null) {
                    loaderProperties.setProperty(path, url.toString());
                }

                try {
                    List urls = Collections.list(classLoader.getResources(path));
                    loaderProperties.setProperty(path + ".count", "" + urls.size());
                    for (int j = 0; j < urls.size(); j++) {
                        loaderProperties.setProperty(path + "." + j, urls.get(j).toString());
                    }
                } catch (IOException e) {
                    throw new MojoExecutionException("Resources could not be enumerated: " + path, e);
                }
            }
        }

        getLog().info("[MAVEN-CORE-IT-LOG] Creating output file " + wagonClassLoaderOutput);

        OutputStream out = null;
        try {
            wagonClassLoaderOutput.getParentFile().mkdirs();
            out = new FileOutputStream(wagonClassLoaderOutput);
            loaderProperties.store(out, "MAVEN-CORE-IT-LOG");
        } catch (IOException e) {
            throw new MojoExecutionException("Output file could not be created: " + wagonClassLoaderOutput, e);
        } finally {
            if (out != null) {
                try {
                    out.close();
                } catch (IOException e) {
                    // just ignore
                }
            }
        }

        getLog().info("[MAVEN-CORE-IT-LOG] Created output file " + wagonClassLoaderOutput);
    }
}