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/*******************************************************************************
* Copyright (c) 2004, 2008 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.core.internal.content;
import java.io.IOException;
import java.io.StringReader;
import javax.xml.parsers.*;
import org.xml.sax.*;
import org.xml.sax.ext.LexicalHandler;
import org.xml.sax.helpers.DefaultHandler;
/**
* A content describer for detecting the name of the top-level element of the
* DTD system identifier in an XML file. This supports two parameters:
* <code>DTD_TO_FIND</code> and <code>ELEMENT_TO_FIND</code>. This is done
* using the <code>IExecutableExtension</code> mechanism. If the
* <code>":-"</code> method is used, then the value is treated as the
* <code>ELEMENT_TO_FIND</code>.
*
* @since 3.0
*/
public final class XMLRootHandler extends DefaultHandler implements LexicalHandler {
/**
* An exception indicating that the parsing should stop. This is usually
* triggered when the top-level element has been found.
*
* @since 3.0
*/
private class StopParsingException extends SAXException {
/**
* All serializable objects should have a stable serialVersionUID
*/
private static final long serialVersionUID = 1L;
/**
* Constructs an instance of <code>StopParsingException</code> with a
* <code>null</code> detail message.
*/
public StopParsingException() {
super((String) null);
}
}
/**
* Should we check the root element?
*/
private boolean checkRoot;
/**
* The system identifier for the DTD that was found while parsing the XML.
* This member variable is <code>null</code> unless the file has been
* parsed successful to the point of finding the DTD's system identifier.
*/
private String dtdFound = null;
/**
* This is the name of the top-level element found in the XML file. This
* member variable is <code>null</code> unless the file has been parsed
* successful to the point of finding the top-level element.
*/
private String elementFound = null;
/**
* This is the namespace of the top-level element found in the XML file. This
* member variable is <code>null</code> unless the file has been parsed
* successful to the point of finding the top-level element.
*/
private String namespaceFound = null;
public XMLRootHandler(boolean checkRoot) {
this.checkRoot = checkRoot;
}
@Override
public final void comment(final char[] ch, final int start, final int length) {
// Not interested.
}
/**
* Creates a new SAX parser for use within this instance.
*
* @return The newly created parser.
*
* @throws ParserConfigurationException
* If a parser of the given configuration cannot be created.
* @throws SAXException
* If something in general goes wrong when creating the parser.
* @throws SAXNotRecognizedException
* If the <code>XMLReader</code> does not recognize the
* lexical handler configuration option.
* @throws SAXNotSupportedException
* If the <code>XMLReader</code> does not support the lexical
* handler configuration option.
*/
private final SAXParser createParser(SAXParserFactory parserFactory) throws ParserConfigurationException, SAXException, SAXNotRecognizedException, SAXNotSupportedException {
// Initialize the parser.
final SAXParser parser = parserFactory.newSAXParser();
final XMLReader reader = parser.getXMLReader();
reader.setProperty("http://xml.org/sax/properties/lexical-handler", this); //$NON-NLS-1$
// disable DTD validation (bug 63625)
try {
// be sure validation is "off" or the feature to ignore DTD's will not apply
reader.setFeature("http://xml.org/sax/features/validation", false); //$NON-NLS-1$
reader.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false); //$NON-NLS-1$
} catch (SAXNotRecognizedException e) {
// not a big deal if the parser does not recognize the features
} catch (SAXNotSupportedException e) {
// not a big deal if the parser does not support the features
}
return parser;
}
@Override
public final void endCDATA() {
// Not interested.
}
@Override
public final void endDTD() {
// Not interested.
}
@Override
public final void endEntity(final String name) {
// Not interested.
}
public String getDTD() {
return dtdFound;
}
public String getRootName() {
return elementFound;
}
/**
* @since org.eclipse.core.contenttype 3.3
*/
public String getRootNamespace() {
return namespaceFound;
}
public boolean parseContents(InputSource contents) throws IOException, ParserConfigurationException, SAXException {
// Parse the file into we have what we need (or an error occurs).
try {
SAXParserFactory factory = Activator.getDefault().getFactory();
if (factory == null)
return false;
final SAXParser parser = createParser(factory);
// to support external entities specified as relative URIs (see bug 63298)
contents.setSystemId("/"); //$NON-NLS-1$
parser.parse(contents, this);
} catch (StopParsingException e) {
// Abort the parsing normally. Fall through...
}
return true;
}
/*
* Resolve external entity definitions to an empty string. This is to speed
* up processing of files with external DTDs. Not resolving the contents
* of the DTD is ok, as only the System ID of the DTD declaration is used.
* @see org.xml.sax.helpers.DefaultHandler#resolveEntity(java.lang.String, java.lang.String)
*/
@Override
public InputSource resolveEntity(String publicId, String systemId) throws SAXException {
return new InputSource(new StringReader("")); //$NON-NLS-1$
}
@Override
public final void startCDATA() {
// Not interested.
}
@Override
public final void startDTD(final String name, final String publicId, final String systemId) throws SAXException {
dtdFound = systemId;
// If we don't care about the top-level element, we can stop here.
if (!checkRoot)
throw new StopParsingException();
}
@Override
public final void startElement(final String uri, final String elementName, final String qualifiedName, final Attributes attributes) throws SAXException {
elementFound = elementName;
namespaceFound = uri;
throw new StopParsingException();
}
@Override
public final void startEntity(final String name) {
// Not interested.
}
}
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