org.jboss.jdocbook.xslt.resolve.VersionResolver Maven / Gradle / Ivy

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/*
 * jDocBook, processing of DocBook sources as a Maven plugin
 *
 * Copyright (c) 2009, Red Hat Middleware LLC or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Middleware LLC.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.jboss.jdocbook.xslt.resolve;

import java.io.IOException;
import java.net.URL;
import javax.xml.transform.Source;
import javax.xml.transform.TransformerException;
import javax.xml.transform.URIResolver;
import javax.xml.transform.stream.StreamSource;

import org.jboss.jdocbook.Environment;

/**
 * Maps docbook-version based URIs to local classpath lookups.  These URIs are in the form
 * 'http://docbook.sourceforge.net/release/xsl/{version}'
 *
 * @author Steve Ebersole
 */
public class VersionResolver implements URIResolver {
	public static final String BASE_HREF = "http://docbook.sourceforge.net/release/xsl/";

	private Environment environment;
	private final String version;
	private final String versionHref;

	/**
	 * Constructs a VersionResolver instance using the given version.
	 *
	 * @param environment The execution environment
	 * @param version The version.
	 */
	public VersionResolver(Environment environment, String version) {
		this.environment = environment;
		this.version = version;
		this.versionHref = BASE_HREF + version;
	}

	/**
	 * {@inheritDoc}
	 */
	public Source resolve(String href, String base) throws TransformerException {
		if ( href.startsWith( versionHref ) ) {
			return resolve( href );
		}
		else if ( base.startsWith( versionHref ) ) {
			return resolve( base + "/" + href );
		}
		return null;
	}

	private Source resolve(String href) {
		String resource = href.substring( versionHref.length() );
		try {
			URL resourceURL = environment.getResourceHelper().requireResource( resource );
			return new StreamSource( resourceURL.openStream(), resourceURL.toExternalForm() );
		}
		catch ( IllegalArgumentException e ) {
			return null;
		}
		catch ( IOException e ) {
			return null;
		}
	}

	/**
	 * {@inheritDoc}
	 */
	public String toString() {
		return super.toString() + " [version=" + version + "]";
	}
}