org.springframework.webflow.engine.builder.xml.DefaultDocumentLoader Maven / Gradle / Ivy
/*
* Copyright 2002-2006 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.webflow.engine.builder.xml;
import java.io.IOException;
import java.io.InputStream;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.core.io.Resource;
import org.springframework.util.xml.SimpleSaxErrorHandler;
import org.w3c.dom.Document;
import org.xml.sax.EntityResolver;
import org.xml.sax.SAXException;
/**
* The default document loader strategy for XSD-based XML documents with
* validation enabled by default.
*
* Note: full XSD support requires JDK 5.0 or a capable parser such as Xerces
* 2.0. JDK 1.4 or < do not fully support XSD out of the box. To use this
* implementation on JDK 1.4 make sure Xerces is available in your classpath or
* disable XSD validation by
* {@link #setValidating(boolean) setting the validating property to false}.
*
* @author Keith Donald
*/
public class DefaultDocumentLoader implements DocumentLoader {
private static final Log logger = LogFactory.getLog(DefaultDocumentLoader.class);
/**
* JAXP attribute used to configure the schema language for validation.
*/
private static final String SCHEMA_LANGUAGE_ATTRIBUTE = "http://java.sun.com/xml/jaxp/properties/schemaLanguage";
/**
* JAXP attribute value indicating the XSD schema language.
*/
private static final String XSD_SCHEMA_LANGUAGE = "http://www.w3.org/2001/XMLSchema";
/**
* Flag indicating if the XML document parser will perform schema
* validation.
*/
private boolean validating = true;
/**
* The spring-webflow schema resolution strategy.
*/
private EntityResolver entityResolver = new WebFlowEntityResolver();
/**
* Returns whether or not the XML parser will validate the document.
*/
public boolean isValidating() {
return validating;
}
/**
* Set if the XML parser should validate the document and thus enforce a
* schema. Defaults to true.
*/
public void setValidating(boolean validating) {
this.validating = validating;
}
/**
* Returns the SAX entity resolver used by the XML parser.
*/
public EntityResolver getEntityResolver() {
return entityResolver;
}
/**
* Set a SAX entity resolver to be used for parsing. Can be overridden for
* custom entity resolution, for example relative to some specific base
* path.
* @see org.springframework.webflow.engine.builder.xml.WebFlowEntityResolver
*/
public void setEntityResolver(EntityResolver entityResolver) {
this.entityResolver = entityResolver;
}
public Document loadDocument(Resource resource) throws IOException, ParserConfigurationException, SAXException {
InputStream is = null;
try {
is = resource.getInputStream();
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setValidating(isValidating());
factory.setNamespaceAware(true);
try {
factory.setAttribute(SCHEMA_LANGUAGE_ATTRIBUTE, XSD_SCHEMA_LANGUAGE);
}
catch (IllegalArgumentException ex) {
throw new IllegalStateException("Unable to validate using XSD: Your JAXP provider [" + factory
+ "] does not support XML Schema. "
+ "Are you running on Java 1.4 or below with Apache Crimson? "
+ "If so you must upgrade to Apache Xerces (or Java 5 or >) for full XSD support.");
}
DocumentBuilder docBuilder = factory.newDocumentBuilder();
docBuilder.setErrorHandler(new SimpleSaxErrorHandler(logger));
docBuilder.setEntityResolver(getEntityResolver());
return docBuilder.parse(is);
}
finally {
if (is != null) {
is.close();
}
}
}
}