/**
* Copyright (C) 2013 Christian Kohlschütter (ckkohl79@gmail.com)
*
* 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 de.l3s.boilerpipe.sax;
import java.io.IOException;
import java.io.StringReader;
import java.net.URL;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import mf.org.apache.xerces.parsers.AbstractSAXParser;
import org.cyberneko.html.HTMLConfiguration;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import de.l3s.boilerpipe.BoilerpipeExtractor;
import de.l3s.boilerpipe.BoilerpipeProcessingException;
import de.l3s.boilerpipe.document.Image;
import de.l3s.boilerpipe.document.TextBlock;
import de.l3s.boilerpipe.document.TextDocument;
/**
* Extracts the images that are enclosed by extracted content.
*
* @author Christian Kohlschütter
*/
public final class ImageExtractor {
public static final ImageExtractor INSTANCE = new ImageExtractor();
/**
* Returns the singleton instance of {@link de.l3s.boilerpipe.sax.ImageExtractor}.
*
* @return the singleton instance of {@link de.l3s.boilerpipe.sax.ImageExtractor}.
*/
public static ImageExtractor getInstance() {
return INSTANCE;
}
private ImageExtractor() {
}
/**
* Processes the given {@link TextDocument} and the original HTML text (as a
* String).
*
* @param doc
* The processed {@link TextDocument}.
* @param origHTML
* The original HTML document.
* @return A List of enclosed {@link Image}s
* @throws BoilerpipeProcessingException
*/
public List<Image> process(final TextDocument doc,
final String origHTML) throws BoilerpipeProcessingException {
return process(doc, new InputSource(
new StringReader(origHTML)));
}
/**
* Processes the given {@link TextDocument} and the original HTML text (as an
* {@link org.xml.sax.InputSource}).
*
* @param doc
* The processed {@link TextDocument}.
* The original HTML document.
* @return A List of enclosed {@link Image}s
* @throws BoilerpipeProcessingException
*/
public List<Image> process(final TextDocument doc,
final InputSource is) throws BoilerpipeProcessingException {
final Implementation implementation = new Implementation();
implementation.process(doc, is);
return implementation.linksHighlight;
}
/**
* Fetches the given {@link java.net.URL} using {@link de.l3s.boilerpipe.sax.HTMLFetcher} and processes the
* retrieved HTML using the specified {@link BoilerpipeExtractor}.
*
* The processed {@link TextDocument}.
* The original HTML document.
* @return A List of enclosed {@link Image}s
* @throws BoilerpipeProcessingException
*/
public List<Image> process(final URL url, final BoilerpipeExtractor extractor)
throws IOException, BoilerpipeProcessingException, SAXException {
final HTMLDocument htmlDoc = HTMLFetcher.fetch(url);
final TextDocument doc = new BoilerpipeSAXInput(htmlDoc.toInputSource())
.getTextDocument();
extractor.process(doc);
final InputSource is = htmlDoc.toInputSource();
return process(doc, is);
}
private final class Implementation extends AbstractSAXParser implements
ContentHandler {
List<Image> linksHighlight = new ArrayList<Image>();
private List<Image> linksBuffer = new ArrayList<Image>();
private int inIgnorableElement = 0;
private int characterElementIdx = 0;
private final BitSet contentBitSet = new BitSet();
private boolean inHighlight = false;
Implementation() {
super(new HTMLConfiguration());
setContentHandler(this);
}
void process(final TextDocument doc, final InputSource is)
throws BoilerpipeProcessingException {
for (TextBlock block : doc.getTextBlocks()) {
if (block.isContent()) {
final BitSet bs = block.getContainedTextElements();
if (bs != null) {
contentBitSet.or(bs);
}
}
}
try {
parse(is);
} catch (SAXException e) {
throw new BoilerpipeProcessingException(e);
} catch (IOException e) {
throw new BoilerpipeProcessingException(e);
}
}
public void endDocument() throws SAXException {
}
public void endPrefixMapping(String prefix) throws SAXException {
}
public void ignorableWhitespace(char[] ch, int start, int length)
throws SAXException {
}
public void processingInstruction(String target, String data)
throws SAXException {
}
public void setDocumentLocator(Locator locator) {
}
public void skippedEntity(String name) throws SAXException {
}
public void startDocument() throws SAXException {
}
public void startElement(String uri, String localName, String qName,
Attributes atts) throws SAXException {
TagAction ta = TAG_ACTIONS.get(localName);
if (ta != null) {
ta.beforeStart(this, localName);
}
try {
if (inIgnorableElement == 0) {
if(inHighlight && "IMG".equalsIgnoreCase(localName)) {
String src = atts.getValue("src");
if(src != null && src.length() > 0) {
linksBuffer.add(new Image(src, atts.getValue("width"), atts.getValue("height"), atts.getValue("alt")));
}
}
}
} finally {
if (ta != null) {
ta.afterStart(this, localName);
}
}
}
public void endElement(String uri, String localName, String qName)
throws SAXException {
TagAction ta = TAG_ACTIONS.get(localName);
if (ta != null) {
ta.beforeEnd(this, localName);
}
try {
if (inIgnorableElement == 0) {
//
}
} finally {
if (ta != null) {
ta.afterEnd(this, localName);
}
}
}
public void characters(char[] ch, int start, int length)
throws SAXException {
characterElementIdx++;
if (inIgnorableElement == 0) {
boolean highlight = contentBitSet.get(characterElementIdx);
if(!highlight) {
if(length == 0) {
return;
}
boolean justWhitespace = true;
for(int i=start;i<start+length;i++) {
if(!Character.isWhitespace(ch[i])) {
justWhitespace = false;
break;
}
}
if(justWhitespace) {
return;
}
}
inHighlight = highlight;
if(inHighlight) {
linksHighlight.addAll(linksBuffer);
linksBuffer.clear();
}
}
}
public void startPrefixMapping(String prefix, String uri)
throws SAXException {
}
}
private static final TagAction TA_IGNORABLE_ELEMENT = new TagAction() {
void beforeStart(final Implementation instance, final String localName) {
instance.inIgnorableElement++;
}
void afterEnd(final Implementation instance, final String localName) {
instance.inIgnorableElement--;
}
};
private static Map<String, TagAction> TAG_ACTIONS = new HashMap<String, TagAction>();
static {
TAG_ACTIONS.put("STYLE", TA_IGNORABLE_ELEMENT);
TAG_ACTIONS.put("SCRIPT", TA_IGNORABLE_ELEMENT);
TAG_ACTIONS.put("OPTION", TA_IGNORABLE_ELEMENT);
TAG_ACTIONS.put("NOSCRIPT", TA_IGNORABLE_ELEMENT);
TAG_ACTIONS.put("EMBED", TA_IGNORABLE_ELEMENT);
TAG_ACTIONS.put("APPLET", TA_IGNORABLE_ELEMENT);
TAG_ACTIONS.put("LINK", TA_IGNORABLE_ELEMENT);
TAG_ACTIONS.put("HEAD", TA_IGNORABLE_ELEMENT);
}
private abstract static class TagAction {
void beforeStart(final Implementation instance, final String localName) {
}
void afterStart(final Implementation instance, final String localName) {
}
void beforeEnd(final Implementation instance, final String localName) {
}
void afterEnd(final Implementation instance, final String localName) {
}
}
}