src/main/java/org/apache/maven/plugins/assembly/filter/SimpleAggregatingDescriptorHandler.java

package org.apache.maven.plugins.assembly.filter;

/*
 * 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.plugins.assembly.utils.AssemblyFileUtils;
import org.codehaus.plexus.archiver.Archiver;
import org.codehaus.plexus.archiver.ArchiverException;
import org.codehaus.plexus.archiver.UnArchiver;
import org.codehaus.plexus.component.annotations.Component;
import org.codehaus.plexus.components.io.fileselectors.FileInfo;
import org.codehaus.plexus.logging.LogEnabled;
import org.codehaus.plexus.logging.Logger;
import org.codehaus.plexus.logging.console.ConsoleLogger;
import org.codehaus.plexus.util.IOUtil;

import javax.annotation.Nonnull;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.StringWriter;
import java.io.Writer;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.List;

/**
 *
 */
@Component( role = ContainerDescriptorHandler.class, hint = "file-aggregator", instantiationStrategy = "per-lookup" )
public class SimpleAggregatingDescriptorHandler
    implements ContainerDescriptorHandler, LogEnabled
{

    // component configuration.

    @SuppressWarnings( "FieldCanBeLocal" )
    private final String commentChars = "#";

    private final StringWriter aggregateWriter = new StringWriter();

    private final List<String> filenames = new ArrayList<>();

    // calculated, temporary values.

    private String filePattern;

    private String outputPath;

    private boolean overrideFilterAction;

    // injected by the container.

    private Logger logger;

    @Override
    public void finalizeArchiveCreation( final Archiver archiver )
    {
        checkConfig();

        if ( outputPath.endsWith( "/" ) )
        {
            throw new ArchiverException( "Cannot write aggregated properties to a directory. "
                                             + "You must specify a file name in the outputPath configuration for this"
                                             + " handler. (handler: " + getClass().getName() );
        }

        if ( outputPath.startsWith( "/" ) )
        {
            outputPath = outputPath.substring( 1 );
        }

        final File temp = writePropertiesFile();

        overrideFilterAction = true;

        archiver.addFile( temp, outputPath );

        overrideFilterAction = false;
    }

    private File writePropertiesFile()
    {
        File f;

        Writer writer = null;
        try
        {
            f = File.createTempFile( "maven-assembly-plugin", "tmp" );
            f.deleteOnExit();

            writer = AssemblyFileUtils.isPropertyFile( f )
                         ? new OutputStreamWriter( new FileOutputStream( f ), StandardCharsets.ISO_8859_1 )
                         : new OutputStreamWriter( new FileOutputStream( f ) ); // Still platform encoding

            writer.write( commentChars + " Aggregated on " + new Date() + " from: " );

            for ( final String filename : filenames )
            {
                writer.write( "\n" + commentChars + " " + filename );
            }

            writer.write( "\n\n" );

            writer.write( aggregateWriter.toString() );

            writer.close();
            writer = null;
        }
        catch ( final IOException e )
        {
            throw new ArchiverException(
                "Error adding aggregated properties to finalize archive creation. Reason: " + e.getMessage(), e );
        }
        finally
        {
            IOUtil.close( writer );
        }

        return f;
    }

    @Override
    public void finalizeArchiveExtraction( final UnArchiver unarchiver )
    {
    }

    @Override
    public List<String> getVirtualFiles()
    {
        checkConfig();

        return Collections.singletonList( outputPath );
    }

    @Override
    public boolean isSelected( @Nonnull final FileInfo fileInfo )
        throws IOException
    {
        checkConfig();

        if ( overrideFilterAction )
        {
            return true;
        }

        String name = AssemblyFileUtils.normalizeFileInfo( fileInfo );

        if ( fileInfo.isFile() && name.matches( filePattern ) )
        {
            readProperties( fileInfo );
            filenames.add( name );

            return false;
        }

        return true;
    }

    private void checkConfig()
    {
        if ( filePattern == null || outputPath == null )
        {
            throw new IllegalStateException(
                "You must configure filePattern and outputPath in your containerDescriptorHandler declaration." );
        }
    }

    private void readProperties( final FileInfo fileInfo )
        throws IOException
    {
        try ( StringWriter writer = new StringWriter();
            Reader reader = AssemblyFileUtils.isPropertyFile( fileInfo.getName() )
                ? new InputStreamReader( fileInfo.getContents(), StandardCharsets.ISO_8859_1 )
                : new InputStreamReader( fileInfo.getContents() ) ) // platform encoding
        {
            IOUtil.copy( reader, writer );
            final String content = writer.toString();
            aggregateWriter.write( "\n" );
            aggregateWriter.write( content );
        }
    }

    protected final Logger getLogger()
    {
        if ( logger == null )
        {
            logger = new ConsoleLogger( Logger.LEVEL_INFO, "" );
        }

        return logger;
    }

    @Override
    public void enableLogging( final Logger logger )
    {
        this.logger = logger;
    }

    @SuppressWarnings( "UnusedDeclaration" )
    public String getFilePattern()
    {
        return filePattern;
    }

    @SuppressWarnings( "UnusedDeclaration" )
    public void setFilePattern( final String filePattern )
    {
        this.filePattern = filePattern;
    }

    @SuppressWarnings( "UnusedDeclaration" )
    public String getOutputPath()
    {
        return outputPath;
    }

    @SuppressWarnings( "UnusedDeclaration" )
    public void setOutputPath( final String outputPath )
    {
        this.outputPath = outputPath;
    }

}