Locator.java

package org.codehaus.mojo.jalopy;

/*
 * 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;
import org.apache.maven.plugin.logging.SystemStreamLog;
import org.codehaus.plexus.util.FileUtils;
import org.codehaus.plexus.util.StringUtils;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.net.URL;

/**
 * Performs Locator services for the <code>*Location</code> parameters in the
 * Reports.
 * <p>
 * Copied from the maven-checkstyle-plugin.  
 *
 * @author <a href="mailto:joakim@erdfelt.com">Joakim Erdfelt</a>
 */
public class Locator
{
    private Log log;

    private File localDir;

    /**
     * Create a Locator object.
     *
     * @param log       the logger object to log with.
     * @param resolveToDir the directory to resolve resources into.
     */
    public Locator( Log log, File resolveToDir )
    {
        this.log = log;
        this.localDir = resolveToDir;
    }

    /**
     * Obtain a Log object.
     *
     * @return the Log object.
     */
    private Log getLog()
    {
        if ( this.log == null )
        {
            this.log = new SystemStreamLog();
        }
        return this.log;
    }

    /**
     * <p>
     * Attempts to resolve a location parameter into a real file.
     * </p>
     *
     * <p/>
     * Checks a location string to for a resource, URL, or File that matches.
     * If a resource or URL is found, then a local file is created with that
     * locations contents.
     * </p>
     *
     * @param location  the location string to match against.
     * @param localfile the local file to use in case of resource or URL.
     * @return the File of the resolved location.
     * @throws IOException if file is unable to be found or copied into <code>localfile</code> destination.
     */
    public File resolveLocation( String location, String localfile )
        throws IOException
    {
        getLog().debug( "resolveLocation(" + location + ", " + localfile + ")" );
        if ( StringUtils.isEmpty( location ) )
        {
            return null;
        }

        File retFile = new File( localDir, localfile );

        // Attempt a URL
        if ( location.indexOf( "://" ) > 1 )
        {
            // Found a URL
            URL url = new URL( location );
            getLog().debug( "Potential URL: " + url.toExternalForm() );
            FileUtils.copyURLToFile( url, retFile );
        }
        else
        {
            getLog().debug( "Location is not a URL." );
            // Attempt a File.
            File fileLocation = new File( location );
            if ( fileLocation.exists() )
            {
                // Found a File.
                getLog().debug( "Potential File: " + fileLocation.getAbsolutePath() );
                FileUtils.copyFile( fileLocation, retFile );
            }
            else
            {
                getLog().debug( "Location is not a File." );
                // Attempt a Resource.
                URL url = this.getClass().getClassLoader().getResource( location );
                if ( url != null )
                {
                    // Found a Resource.
                    getLog().debug( "Potential Resource: " + url.toExternalForm() );
                    FileUtils.copyURLToFile( url, retFile );
                }
                else
                {
                    getLog().debug( "Location is not a Resource." );
                    throw new IOException( "Unable to find location '" + location
                        + "' as URL, File or Resource. Working dir is " + new File( "" ).getAbsolutePath() );
                }
            }
        }

        if ( !retFile.exists() )
        {
            throw new FileNotFoundException( "Destination file does not exist." );
        }

        if ( retFile.length() <= 0 )
        {
            throw new IOException( "Destination file has no content: " + retFile + ". Is " + location + " empty?" );
        }

        return retFile;
    }
}