AbstractMojo

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package org.apache.maven.plugin;

import java.util.Map;

import org.apache.maven.plugin.logging.Log;
import org.apache.maven.plugin.logging.SystemStreamLog;

/**
 * Abstract class to provide most of the infrastructure required to implement a <code>Mojo</code> except for
 * the execute method.<br>
 * The implementation should have a <code>Mojo</code> annotation with the name of the goal:
 * <pre>
 *   &#64;Mojo( name = "&lt;goal-name&gt;" )
 * </pre>
 * <p>
 * There are also a number of attributes which can be used to control how and when the
 * <code>Mojo</code> is executed:
 * </p>
 * <table border="1">
 *  <caption>mojo annotation attributes</caption>
 *  <tr>
 *      <th>Descriptor Element</th>
 *      <th>Annotation</th>
 *      <th>Required?</th>
 *      <th>Notes</th>
 *  </tr>
 *  <tr>
 *      <td>goal</td>
 *      <td>name = "&lt;goal-name&gt;"</td>
 *      <td>Yes</td>
 *      <td>The name for the Mojo that users will reference from the command line to execute the Mojo directly,
 *      or inside a POM in order to provide Mojo-specific configuration.</td>
 *  </tr>
 *  <tr>
 *      <td>implementation</td>
 *      <td>none (detected)</td>
 *      <td>Yes</td>
 *      <td>The Mojo's fully-qualified class name (or script path in the case of non-Java Mojos).</td>
 *  </tr>
 *  <tr>
 *      <td>language</td>
 *      <td>none (detected)</td>
 *      <td>No. Default: <code>java</code></td>
 *      <td>The implementation language for this Mojo (Java, beanshell, etc.).</td>
 *  </tr>
 *  <tr>
 *      <td>configurator</td>
 *      <td>configurator = "&lt;role-hint&gt;"</td>
 *      <td>No</td>
 *      <td>The configurator type to use when injecting parameter values into this Mojo. The value is normally
 *          deduced from the Mojo's implementation language, but can be specified to allow a custom
 *          ComponentConfigurator implementation to be used.
 *          <br>
 *          <i>NOTE: This will only be used in very special cases, using a highly controlled vocabulary of possible
 *          values. (Elements like this are why it's a good idea to use the descriptor tools.)</i>
 *      </td>
 *   </tr>
 *   <tr>
 *      <td>phase</td>
 *      <td>defaultPhase = LifecyclePhase.&lt;phase&gt;</td>
 *      <td>No</td>
 *      <td>Binds this Mojo to a particular phase of the standard build lifecycle, if specified.
 *          <br>
 *          <i>NOTE: This is only required if this Mojo is to participate in the standard build process.</i>
 *      </td>
 *   </tr>
 *   <tr>
 *      <td>execute</td>
 *      <td>@Execute
 *       ( phase=LifecyclePhase.&lt;phase&gt;, goal= "&lt;goal-name&gt;", lifecycle="&lt;lifecycle-id&gt;" )</td>
 *      <td>No</td>
 *      <td>When this goal is invoked, it will first invoke a parallel lifecycle, ending at the given phase.
 *          If a goal is provided instead of a phase, that goal will be executed in isolation.
 *          The execution of either will not affect the current project, but instead make available the
 *          <code>${executedProject}</code> expression if required. An alternate lifecycle can also be provided:
 *          for more information see the documentation on the
 *          <a href="https://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html"
 *             target="_blank">build lifecycle</a>.
 *      </td>
 *   </tr>
 *   <tr>
 *      <td>requiresDependencyResolution</td>
 *      <td>requiresDependencyResolution = ResolutionScope.&lt;scope&gt;</td>
 *      <td>No</td>
 *      <td>Flags this Mojo as requiring the dependencies in the specified scope (or an implied scope) to be
 *          resolved before it can execute.
 *          <br>
 *          <i>NOTE: Currently supports <b>compile</b>, <b>runtime</b>, and <b>test</b> scopes.</i>
 *      </td>
 *   </tr>
 *   <tr>
 *      <td>description</td>
 *      <td>none (detected)</td>
 *      <td>No</td>
 *      <td>The description of this Mojo's functionality. Using the toolset, this will be the class-level
 *          Javadoc description provided.<br>
 *          <i>NOTE: While this is not a required part of the Mojo specification, it <b>SHOULD</b> be provided to
 *          enable future tool support for browsing, etc. and for clarity.</i>
 *      </td>
 *   </tr>
 *   <tr>
 *      <td>parameters</td>
 *      <td>N/A</td>
 *      <td>No</td>
 *      <td>Specifications for the parameters which this Mojo uses will be provided in <b>parameter</b> sub-elements
 *          in this section.
 *          <br>
 *          <i>NOTE: Parameters are discussed in more detail below.</i>
 *      </td>
 *   </tr>
 * </table>
 * <p>This is only a small set of all the options. A complete list can be found at
 * <a href="https://maven.apache.org/components/plugin-tools/maven-plugin-tools-annotations/index.html" target="_blank">
 * Maven Plugin Tool for Annotations</a>.
 *
 * @see <a href="https://maven.apache.org/guides/plugin/guide-java-plugin-development.html" target="_blank">Guide to Developing Java Plugins</a>
 * @see <a href="https://maven.apache.org/guides/mini/guide-configuring-plugins.html" target="_blank">Guide to Configuring Plug-ins</a>
 * @see <a href="https://maven.apache.org/developers/mojo-api-specification.html" target="_blank">Mojo API Specification</a>
 *
 * @author <a href="mailto:brett@apache.org">Brett Porter</a>
 * @author jdcasey
 * @author <a href="mailto:vincent.siveton@gmail.com">Vincent Siveton</a>
 */
public abstract class AbstractMojo implements Mojo, ContextEnabled {
    /** Instance logger */
    private Log log;

    /** Plugin container context */
    private Map pluginContext;

    @Override
    public void setLog(Log log) {
        this.log = log;
    }

    /**
     * <p>
     * Returns the logger that has been injected into this mojo. If no logger has been setup yet, a
     * <code>SystemStreamLog</code> logger will be created and returned.
     * </p>
     * <strong>Note:</strong>
     * The logger returned by this method must not be cached in an instance field during the construction of the mojo.
     * This would cause the mojo to use a wrongly configured default logger when being run by Maven. The proper logger
     * gets injected by the Plexus container <em>after</em> the mojo has been constructed. Therefore, simply call this
     * method directly whenever you need the logger, it is fast enough and needs no caching.
     *
     * @see org.apache.maven.plugin.Mojo#getLog()
     */
    @Override
    public Log getLog() {
        if (log == null) {
            log = new SystemStreamLog();
        }

        return log;
    }

    @Override
    public Map getPluginContext() {
        return pluginContext;
    }

    @Override
    public void setPluginContext(Map pluginContext) {
        this.pluginContext = pluginContext;
    }
}