/*
* 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.
*/
package org.apache.commons.jxpath.xml;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.HashMap;
import org.apache.commons.jxpath.Container;
import org.apache.commons.jxpath.JXPathException;
/**
* An XML document container reads and parses XML only when it is
* accessed. JXPath traverses Containers transparently -
* you use the same paths to access objects in containers as you
* do to access those objects directly. You can create
* XMLDocumentContainers for various XML documents that may or
* may not be accessed by XPaths. If they are, they will be automatically
* read, parsed and traversed. If they are not - they won't be
* read at all.
*
* @author Dmitri Plotnikov
* @version $Revision: 668329 $ $Date: 2008-06-16 16:59:48 -0500 (Mon, 16 Jun 2008) $
*/
public class DocumentContainer extends XMLParser2 implements Container {
/** DOM constant */
public static final String MODEL_DOM = "DOM";
/** JDOM constant */
public static final String MODEL_JDOM = "JDOM";
private static final long serialVersionUID = -8713290334113427066L;
private static HashMap parserClasses = new HashMap();
static {
parserClasses.put(MODEL_DOM,
"org.apache.commons.jxpath.xml.DOMParser");
parserClasses.put(MODEL_JDOM,
"org.apache.commons.jxpath.xml.JDOMParser");
}
private static HashMap parsers = new HashMap();
private Object document;
private URL xmlURL;
private String model;
/**
* Add an XML parser. Parsers for the models "DOM" and "JDOM" are
* pre-registered.
* @param model model name
* @param parser parser
*/
public static void registerXMLParser(String model, XMLParser parser) {
parsers.put(model, parser);
}
/**
* Add a class of a custom XML parser.
* Parsers for the models "DOM" and "JDOM" are pre-registered.
* @param model model name
* @param parserClassName parser classname
*/
public static void registerXMLParser(String model, String parserClassName) {
parserClasses.put(model, parserClassName);
}
/**
* Use this constructor if the desired model is DOM.
*
* @param xmlURL is a URL for an XML file.
* Use getClass().getResource(resourceName) to load XML from a
* resource file.
*/
public DocumentContainer(URL xmlURL) {
this(xmlURL, MODEL_DOM);
}
/**
* Construct a new DocumentContainer.
* @param xmlURL is a URL for an XML file. Use getClass().getResource
* (resourceName) to load XML from a resource file.
*
* @param model is one of the MODEL_* constants defined in this class. It
* determines which parser should be used to load the XML.
*/
public DocumentContainer(URL xmlURL, String model) {
this.xmlURL = xmlURL;
if (xmlURL == null) {
throw new JXPathException("XML URL is null");
}
this.model = model;
}
/**
* Reads XML, caches it internally and returns the Document.
* @return Object
*/
public Object getValue() {
if (document == null) {
try {
InputStream stream = null;
try {
if (xmlURL != null) {
stream = xmlURL.openStream();
}
document = parseXML(stream);
}
finally {
if (stream != null) {
stream.close();
}
}
}
catch (IOException ex) {
throw new JXPathException(
"Cannot read XML from: " + xmlURL.toString(),
ex);
}
}
return document;
}
/**
* Parses XML using the parser for the specified model.
* @param stream InputStream
* @return Object
*/
public Object parseXML(InputStream stream) {
XMLParser parser = getParser(model);
if (parser instanceof XMLParser2) {
XMLParser2 parser2 = (XMLParser2) parser;
parser2.setValidating(isValidating());
parser2.setNamespaceAware(isNamespaceAware());
parser2.setIgnoringElementContentWhitespace(
isIgnoringElementContentWhitespace());
parser2.setExpandEntityReferences(isExpandEntityReferences());
parser2.setIgnoringComments(isIgnoringComments());
parser2.setCoalescing(isCoalescing());
}
return parser.parseXML(stream);
}
/**
* Throws an UnsupportedOperationException.
* @param value value (not) to set
*/
public void setValue(Object value) {
throw new UnsupportedOperationException();
}
/**
* Maps a model type to a parser.
* @param model input model type
* @return XMLParser
*/
private static XMLParser getParser(String model) {
XMLParser parser = (XMLParser) parsers.get(model);
if (parser == null) {
String className = (String) parserClasses.get(model);
if (className == null) {
throw new JXPathException("Unsupported XML model: " + model);
}
try {
Class clazz = Class.forName(className);
parser = (XMLParser) clazz.newInstance();
}
catch (Exception ex) {
throw new JXPathException(
"Cannot allocate XMLParser: " + className, ex);
}
parsers.put(model, parser);
}
return parser;
}
}