com.humingo.util.HtmlContentHandler.java Source code

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Here is the source code for com.humingo.util.HtmlContentHandler.java

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/**
 * 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 com.humingo.util;

import com.humingo.model.CrawlContext;

import org.apache.commons.lang3.StringUtils;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class HtmlContentHandler extends DefaultHandler {

    private final int MAX_ANCHOR_LENGTH = 100;

    private enum Element {
        A, AREA, LINK, IFRAME, FRAME, EMBED, IMG, BASE, META, BODY
    }

    private static class HtmlFactory {
        private static Map<String, Element> name2Element;

        static {
            name2Element = new HashMap<String, Element>();
            for (Element element : Element.values()) {
                name2Element.put(element.toString().toLowerCase(), element);
            }
        }

        public static Element getElement(String name) {
            return name2Element.get(name);
        }
    }

    private String base;
    private String metaRefresh;
    private String metaLocation;

    private boolean isWithinBodyElement;
    private StringBuilder bodyText;

    private List<String> outgoingUrls;

    private CrawlContext curUrl = null;
    private boolean anchorFlag = false;
    private StringBuilder anchorText = new StringBuilder();

    public HtmlContentHandler() {
        isWithinBodyElement = false;
        bodyText = new StringBuilder();
        outgoingUrls = new ArrayList<String>();
    }

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes)
            throws SAXException {
        Element element = HtmlFactory.getElement(localName);
        String curUrl = null;
        if (element == Element.A || element == Element.AREA || element == Element.LINK) {
            String href = attributes.getValue("href");
            if (href != null) {
                curUrl = href;
            }
        }

        if (element == Element.IMG) {
            String imgSrc = attributes.getValue("src");
            if (imgSrc != null) {
                curUrl = imgSrc;
            }
        }

        if (element == Element.IFRAME || element == Element.FRAME || element == Element.EMBED) {
            String src = attributes.getValue("src");
            if (src != null) {
                curUrl = src;

            }
        }

        if (element == Element.BASE) {
            if (base != null) { // We only consider the first occurrence of the
                // Base element.
                String href = attributes.getValue("href");
                if (href != null) {
                    base = href;
                }
            }
        }

        if (element == Element.META) {
            String equiv = attributes.getValue("http-equiv");
            String content = attributes.getValue("content");
            if (equiv != null && content != null) {
                equiv = equiv.toLowerCase();

                // http-equiv="refresh" content="0;URL=http://foo.bar/..."
                if (equiv.equals("refresh") && (metaRefresh == null)) {
                    int pos = content.toLowerCase().indexOf("url=");
                    if (pos != -1) {
                        content = content.substring(pos + 4);
                    }
                }
                curUrl = content;
            }
        }
        if (StringUtils.isNotBlank(curUrl)) {
            String hrefWithoutProtocol = curUrl.toLowerCase();
            if (curUrl.startsWith("http://")) {
                hrefWithoutProtocol = curUrl.substring(7);
            }
            if (!hrefWithoutProtocol.contains("javascript:") && !hrefWithoutProtocol.contains("mailto:")
                    && !hrefWithoutProtocol.contains("@")) {
                outgoingUrls.add(curUrl);
            }

        }

        if (element == Element.BODY) {
            isWithinBodyElement = true;
        }
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        Element element = HtmlFactory.getElement(localName);
        if (element == Element.A || element == Element.AREA || element == Element.LINK) {
            anchorFlag = false;
            if (curUrl != null) {
                String anchor = anchorText.toString().replaceAll("\n", " ").replaceAll("\t", " ").trim();
                if (!anchor.isEmpty()) {
                    if (anchor.length() > MAX_ANCHOR_LENGTH) {
                        anchor = anchor.substring(0, MAX_ANCHOR_LENGTH) + "...";
                    }
                }
                anchorText.delete(0, anchorText.length());
            }
            curUrl = null;
        }
        if (element == Element.BODY) {
            isWithinBodyElement = false;
        }
    }

    @Override
    public void characters(char ch[], int start, int length) throws SAXException {
        if (isWithinBodyElement) {
            bodyText.append(ch, start, length);

            if (anchorFlag) {
                anchorText.append(new String(ch, start, length));
            }
        }
    }

    public String getBodyText() {
        return bodyText.toString();
    }

    public List<String> getOutgoingUrls() {
        return outgoingUrls;
    }

    public String getBaseUrl() {
        return base;
    }

}