core-integration-testing/core-integration-testing-plugins/maven-it-plugin-generate-properties/src/main/java/org/apache/maven/plugin/coreit/InterpolatedPomConfigurationMojo.java

package org.apache.maven.plugin.coreit;

import org.apache.maven.plugin.AbstractMojo;
import org.apache.maven.plugin.MojoExecutionException;

import java.util.Properties;
import java.io.FileOutputStream;
import java.io.File;

/**
 * Take some configuration values that use interpolated POM values and write them to a properties file
 * to make sure they are passing through the system properly. We are using this mojo in it0088, and the
 * configuration looks like the following:
 * 
 * <plugin>
 *   <groupId>org.apache.maven.its.plugins</groupId>
 *   <artifactId>maven-it-plugin-generate-properties</artifactId>
 *   <version>1.0-SNAPSHOT</version>
 *   <executions>
 *     <execution>
 *       <phase>process-resources</phase>
 *       <configuration>
 *         <projectBuildDirectory>${project.build.directory}</projectBuildDirectory>
 *         <targetDirectoryString>target</targetDirectoryString>
 *         <targetDirectoryFile>target</targetDirectoryFile>
 *       </configuration>
 *       <goals>
 *         <goal>generate-properties</goal>
 *       </goals>
 *     </execution>
 *   </executions>
 * </plugin>
 * 
 * @goal generate-properties
 *
 */
public class InterpolatedPomConfigurationMojo
    extends AbstractMojo
{
    /**
     * @parameter expression="${basedir}"
     */
    private String basedir;

    /**
     * This is using the plugin configuration above and so ${project.build.directory} is the value
     * of the expression ${projectBuildDirectory} and should be the full path to the scratch directory
     * which often looks something like /path/to/project/target. For the 2.0.x family this always results
     * in a full path, and bugs have resulted when it resolves to something that is not a full path like "target".
     *
     * @parameter expression="${projectBuildDirectory}"
     */
    private String projectBuildDirectory;

    /**
     * @parameter expression="${targetDirectoryString}"
     */
    private String targetDirectoryString;

    /**
     * @parameter expression="${targetDirectoryFile}"
     */
    private File targetDirectoryFile;

    public void execute()
        throws MojoExecutionException
    {
        try
        {
            Properties mojoGeneratedPropeties = new Properties();

            mojoGeneratedPropeties.put( "project.build.directory", projectBuildDirectory );
            
            if ( targetDirectoryString != null )
            {
                mojoGeneratedPropeties.put( "targetDirectoryString", targetDirectoryString );
            }    
            if ( targetDirectoryFile != null )
            {
                mojoGeneratedPropeties.put( "targetDirectoryFile", targetDirectoryFile.getAbsolutePath() );
            }    

            FileOutputStream fos = new FileOutputStream( new File( basedir, "target/mojo-generated.properties" ) );

            mojoGeneratedPropeties.store( fos, "# Properties generated by the execution of a mojo that uses interpolated POM values for configuration." );
        }
        catch( Exception e )
        {
            getLog().error( "Error creating mojo generated properties.", e );
        }
    }
}