maven-plugin-api/src/main/java/org/apache/maven/plugin/Mojo.java

package org.apache.maven.plugin;

/*
 * 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.apache.maven.plugin.logging.Log;

/**
 * This interface forms the contract required for <code>Mojos</code> to interact with the <code>Maven</code>
 * infrastructure.
 * <br/>
 * It features an <code>execute()</code> method, which triggers the Mojo's build-process behavior, and can throw
 * a MojoExecutionException or MojoFailureException if error conditions occur.
 * <br/>
 * Also included is the <code>setLog(...)</code> method, which simply allows Maven to inject a logging mechanism which will
 * allow the Mojo to communicate to the outside world through standard Maven channels.
 *
 * @author <a href="mailto:jason@maven.org">Jason van Zyl</a>
 * @version $Id$
 */
public interface Mojo
{
    /** The component <code>role</code> hint for Plexus container */
    String ROLE = Mojo.class.getName();

    /**
     * Perform whatever build-process behavior this <code>Mojo</code> implements.
     * <br/>
     * This is the main trigger for the <code>Mojo</code> inside the <code>Maven</code> system, and allows
     * the <code>Mojo</code> to communicate errors.
     *
     * @throws MojoExecutionException if an unexpected problem occurs.
     * Throwing this exception causes a "BUILD ERROR" message to be displayed.
     * @throws MojoFailureException if an expected problem (such as a compilation failure) occurs.
     * Throwing this exception causes a "BUILD FAILURE" message to be displayed.
     */
    void execute()
        throws MojoExecutionException, MojoFailureException;

    /**
     * Inject a standard <code>Maven</code> logging mechanism to allow this <code>Mojo</code> to communicate events
     * and feedback to the user.
     *
     * @param log a new logger
     */
    // TODO: not sure about this here, and may want a getLog on here as well/instead
    void setLog( Log log );

    /**
     * Furnish access to the standard Maven logging mechanism which is managed in this base class.
     *
     * @return a log4j-like logger object which allows plugins to create messages at levels of <code>"debug"</code>,
     * <code>"info"</code>, <code>"warn"</code>, and <code>"error"</code>. This logger is the accepted means to display
     * information to the user.
     */
    Log getLog();
}