Spring Framework example source code file (BeansDtdResolver.java)

This example Spring Framework source code file (BeansDtdResolver.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

classpathresource, dtd, dtd_names, entityresolver, found, id, id, inputsource, inputsource, io, ioexception, ioexception, sax, string, string, trying

The Spring Framework BeansDtdResolver.java source code

/*
 * Copyright 2002-2007 the original author or authors.
 *
 * Licensed 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.
 */

package org.springframework.beans.factory.xml;

import java.io.IOException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;

import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;

/**
 * EntityResolver implementation for the Spring beans DTD,
 * to load the DTD from the Spring class path (or JAR file).
 *
 * <p>Fetches "spring-beans-2.0.dtd" from the class path resource
 * "/org/springframework/beans/factory/xml/spring-beans-2.0.dtd",
 * no matter whether specified as some local URL that includes "spring-beans"
 * in the DTD name or as "http://www.springframework.org/dtd/spring-beans-2.0.dtd".
 *
 * @author Juergen Hoeller
 * @author Colin Sampaleanu
 * @since 04.06.2003
 * @see ResourceEntityResolver
 */
public class BeansDtdResolver implements EntityResolver {
	
	private static final String DTD_EXTENSION = ".dtd";

	private static final String[] DTD_NAMES = {"spring-beans-2.0", "spring-beans"};

	private static final Log logger = LogFactory.getLog(BeansDtdResolver.class);


	public InputSource resolveEntity(String publicId, String systemId) throws IOException {
		if (logger.isTraceEnabled()) {
			logger.trace("Trying to resolve XML entity with public ID [" + publicId +
					"] and system ID [" + systemId + "]");
		}
		if (systemId != null && systemId.endsWith(DTD_EXTENSION)) {
			int lastPathSeparator = systemId.lastIndexOf("/");
			for (int i = 0; i < DTD_NAMES.length; ++i) {
				int dtdNameStart = systemId.indexOf(DTD_NAMES[i]);
				if (dtdNameStart > lastPathSeparator) {
					String dtdFile = systemId.substring(dtdNameStart);
					if (logger.isTraceEnabled()) {
						logger.trace("Trying to locate [" + dtdFile + "] in Spring jar");
					}
					try {
						Resource resource = new ClassPathResource(dtdFile, getClass());
						InputSource source = new InputSource(resource.getInputStream());
						source.setPublicId(publicId);
						source.setSystemId(systemId);
						if (logger.isDebugEnabled()) {
							logger.debug("Found beans DTD [" + systemId + "] in classpath: " + dtdFile);
						}
						return source;
					}
					catch (IOException ex) {
						if (logger.isDebugEnabled()) {
							logger.debug("Could not resolve beans DTD [" + systemId + "]: not found in class path", ex);
						}
					}
				
				}
			}
		}

		// Use the default behavior -> download from website or wherever.
		return null;
	}

}