PackageComponentMojo.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.camel.maven.packaging;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Collections;
import java.util.Properties;

import org.apache.maven.model.Resource;
import org.apache.maven.plugin.AbstractMojo;
import org.apache.maven.plugin.MojoExecutionException;
import org.apache.maven.plugin.MojoFailureException;
import org.apache.maven.plugin.logging.Log;
import org.apache.maven.project.MavenProject;
import org.apache.maven.project.MavenProjectHelper;
import org.sonatype.plexus.build.incremental.BuildContext;

/**
 * Analyses the Camel plugins in a project and generates extra descriptor information for easier auto-discovery in Camel.
 *
 * @goal generate-components-list
 */
public class PackageComponentMojo extends AbstractMojo {

    /**
     * The maven project.
     *
     * @parameter property="project"
     * @required
     * @readonly
     */
    protected MavenProject project;

    /**
     * The output directory for generated components file
     *
     * @parameter default-value="${project.build.directory}/generated/camel/components"
     */
    protected File componentOutDir;

    /**
     * Maven ProjectHelper.
     *
     * @component
     * @readonly
     */
    private MavenProjectHelper projectHelper;

    /**
     * build context to check changed files and mark them for refresh (used for
     * m2e compatibility)
     * 
     * @component
     * @readonly
     */
    private BuildContext buildContext;

    /**
     * Execute goal.
     *
     * @throws MojoExecutionException execution of the main class or one of the
     *                 threads it generated failed.
     * @throws MojoFailureException something bad happened...
     */
    public void execute() throws MojoExecutionException, MojoFailureException {
        prepareComponent(getLog(), project, projectHelper, componentOutDir, buildContext);
    }

    public static void prepareComponent(Log log, MavenProject project, MavenProjectHelper projectHelper, File componentOutDir, BuildContext buildContext) throws MojoExecutionException {

        File camelMetaDir = new File(componentOutDir, "META-INF/services/org/apache/camel/");

        // first we need to setup the output directory because the next check
        // can stop the build before the end and eclipse always needs to know about that directory 
        if (projectHelper != null) {
            projectHelper.addResource(project, componentOutDir.getPath(), Collections.singletonList("**/component.properties"), Collections.emptyList());
        }

        if (!PackageHelper.haveResourcesChanged(log, project, buildContext, "META-INF/services/org/apache/camel/component")) {
            return;
        }

        StringBuilder buffer = new StringBuilder();
        int count = 0;
        for (Resource r : project.getBuild().getResources()) {
            File f = new File(r.getDirectory());
            if (!f.exists()) {
                f = new File(project.getBasedir(), r.getDirectory());
            }
            f = new File(f, "META-INF/services/org/apache/camel/component");

            if (f.exists() && f.isDirectory()) {
                File[] files = f.listFiles();
                if (files != null) {
                    for (File file : files) {
                        // skip directories as there may be a sub .resolver directory
                        if (file.isDirectory()) {
                            continue;
                        }
                        String name = file.getName();
                        if (name.charAt(0) != '.') {
                            count++;
                            if (buffer.length() > 0) {
                                buffer.append(" ");
                            }
                            buffer.append(name);
                        }
                    }
                }
            }
        }

        if (count > 0) {
            Properties properties = new Properties();
            String names = buffer.toString();
            properties.put("components", names);
            properties.put("groupId", project.getGroupId());
            properties.put("artifactId", project.getArtifactId());
            properties.put("version", project.getVersion());
            properties.put("projectName", project.getName());
            if (project.getDescription() != null) {
                properties.put("projectDescription", project.getDescription());
            }

            camelMetaDir.mkdirs();
            File outFile = new File(camelMetaDir, "component.properties");

            // check if the existing file has the same content, and if so then leave it as is so we do not write any changes
            // which can cause a re-compile of all the source code
            if (outFile.exists()) {
                try {
                    Properties existing = new Properties();

                    InputStream is = new FileInputStream(outFile);
                    existing.load(is);
                    is.close();

                    // are the content the same?
                    if (existing.equals(properties)) {
                        log.debug("No component changes detected");
                        return;
                    }
                } catch (IOException e) {
                    // ignore
                }
            }

            try {
                OutputStream os = buildContext.newFileOutputStream(outFile);
                properties.store(os, "Generated by camel-package-maven-plugin");
                os.close();

                log.info("Generated " + outFile + " containing " + count + " Camel " + (count > 1 ? "components: " : "component: ") + names);

            } catch (IOException e) {
                throw new MojoExecutionException("Failed to write properties to " + outFile + ". Reason: " + e, e);
            }
        } else {
            log.debug("No META-INF/services/org/apache/camel/component directory found. Are you sure you have created a Camel component?");
        }
    }

}