DoctypeUtils.java

package org.jboss.windup.util.xml;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.lang3.StringUtils;

/**
 * Util methods to work with XML DOCTYPE's.
 */
public class DoctypeUtils
{

	public static String extractVersion(String publicId, String systemId) {
		Pattern pattern = Pattern.compile("[0-9][0-9a-zA-Z.-]+");

		if(StringUtils.isNotBlank(publicId)) {
			Matcher matcher = pattern.matcher(publicId);
			if(matcher.find()) {
				return matcher.group();
			}
		}

		if(StringUtils.isNotBlank(systemId)) {
			Matcher matcher = pattern.matcher(systemId);
			if(matcher.find()) {
				String match = matcher.group();

				//for system ID, make sure to remove the ".dtd" that could come in.
				return StringUtils.removeEnd(match, ".dtd");
			}
		}

		return null;
	}
}