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/*******************************************************************************
* Copyright (c) 2006, 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.help.internal.dynamic;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.FactoryConfigurationError;
import javax.xml.parsers.ParserConfigurationException;
import org.eclipse.help.internal.UAElement;
import org.eclipse.help.internal.UAElementFactory;
import org.eclipse.help.internal.entityresolver.LocalEntityResolver;
import org.w3c.dom.Document;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
/**
* This class manages reuse of DOM parsers. It will keep reusing the same DocumentBuilder unless it is being used
* elsewhere in which case a new one is allocated.
*/
public class DocumentReader {
private class ManagedBuilder {
public DocumentBuilder builder;
public boolean inUse;
}
private ManagedBuilder cachedBuilder;
public UAElement read(InputStream in) throws IOException, SAXException, ParserConfigurationException {
return read(in, null);
}
public UAElement read(InputStream in, String charset) throws IOException, SAXException, ParserConfigurationException {
ManagedBuilder managedBuilder = getManagedBuilder();
InputSource input = null;
if (charset != null) {
input = new InputSource(new InputStreamReader(in, charset));
}
else {
input = new InputSource(in);
}
Document document = managedBuilder.builder.parse(input);
managedBuilder.inUse = false;
prepareDocument(document);
return UAElementFactory.newElement(document.getDocumentElement());
}
/**
* Allows subclasses to process the DOM before creating a UA element
*/
protected void prepareDocument(Document document) {
}
private synchronized ManagedBuilder getManagedBuilder() throws FactoryConfigurationError, ParserConfigurationException {
if (cachedBuilder == null || cachedBuilder.inUse) {
cachedBuilder = createManagedBuilder();
}
cachedBuilder.inUse = true;
return cachedBuilder;
}
private ManagedBuilder createManagedBuilder() throws FactoryConfigurationError, ParserConfigurationException {
ManagedBuilder managedBuilder = new ManagedBuilder();
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setNamespaceAware(false);
managedBuilder.builder= factory.newDocumentBuilder();
managedBuilder.builder.setEntityResolver(new LocalEntityResolver());
return managedBuilder;
}
}
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