org.apache.tika.sax.ContentHandlerDecorator Maven / Gradle / Ivy
/*
* 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.tika.sax;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
/**
* Decorator base class for the {@link ContentHandler} interface. This class
* simply delegates all SAX events calls to an underlying decorated handler
* instance. Subclasses can provide extra decoration by overriding one or more
* of the SAX event methods.
*/
public class ContentHandlerDecorator extends DefaultHandler {
/**
* Decorated SAX event handler.
*/
private ContentHandler handler;
/**
* Creates a decorator for the given SAX event handler.
*
* @param handler SAX event handler to be decorated
*/
public ContentHandlerDecorator(ContentHandler handler) {
assert handler != null;
this.handler = handler;
}
/**
* Creates a decorator that by default forwards incoming SAX events to
* a dummy content handler that simply ignores all the events. Subclasses
* should use the {@link #setContentHandler(ContentHandler)} method to
* switch to a more usable underlying content handler.
*/
protected ContentHandlerDecorator() {
this(new DefaultHandler());
}
/**
* Sets the underlying content handler. All future SAX events will be
* directed to this handler instead of the one that was previously used.
*
* @param handler content handler
*/
protected void setContentHandler(ContentHandler handler) {
assert handler != null;
this.handler = handler;
}
@Override
public void startPrefixMapping(String prefix, String uri)
throws SAXException {
try {
handler.startPrefixMapping(prefix, uri);
} catch (SAXException e) {
handleException(e);
}
}
@Override
public void endPrefixMapping(String prefix) throws SAXException {
try {
handler.endPrefixMapping(prefix);
} catch (SAXException e) {
handleException(e);
}
}
@Override
public void processingInstruction(String target, String data)
throws SAXException {
try {
handler.processingInstruction(target, data);
} catch (SAXException e) {
handleException(e);
}
}
@Override
public void setDocumentLocator(Locator locator) {
handler.setDocumentLocator(locator);
}
@Override
public void startDocument() throws SAXException {
try {
handler.startDocument();
} catch (SAXException e) {
handleException(e);
}
}
@Override
public void endDocument() throws SAXException {
try {
handler.endDocument();
} catch (SAXException e) {
handleException(e);
}
}
@Override
public void startElement(
String uri, String localName, String name, Attributes atts)
throws SAXException {
try {
handler.startElement(uri, localName, name, atts);
} catch (SAXException e) {
handleException(e);
}
}
@Override
public void endElement(String uri, String localName, String name)
throws SAXException {
try {
handler.endElement(uri, localName, name);
} catch (SAXException e) {
handleException(e);
}
}
@Override
public void characters(char[] ch, int start, int length)
throws SAXException {
try {
handler.characters(ch, start, length);
} catch (SAXException e) {
handleException(e);
}
}
@Override
public void ignorableWhitespace(char[] ch, int start, int length)
throws SAXException {
try {
handler.ignorableWhitespace(ch, start, length);
} catch (SAXException e) {
handleException(e);
}
}
@Override
public void skippedEntity(String name) throws SAXException {
try {
handler.skippedEntity(name);
} catch (SAXException e) {
handleException(e);
}
}
@Override
public String toString() {
return handler.toString();
}
/**
* Handle any exceptions thrown by methods in this class. This method
* provides a single place to implement custom exception handling. The
* default behaviour is simply to re-throw the given exception, but
* subclasses can also provide alternative ways of handling the situation.
*
* @param exception the exception that was thrown
* @throws SAXException the exception (if any) thrown to the client
*/
protected void handleException(SAXException exception) throws SAXException {
throw exception;
}
}