ParseFilter.java

/**
 * Licensed to DigitalPebble Ltd under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * DigitalPebble 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
 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p/>
 * 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.digitalpebble.stormcrawler.parse;

import java.util.Map;

import org.w3c.dom.DocumentFragment;

import com.fasterxml.jackson.databind.JsonNode;

/**
 * Implementations of ParseFilter are responsible for extracting custom data
 * from the crawled content. They are managed by the
 * {@link com.digitalpebble.stormcrawler.bolt.JSoupParserBolt}
 */
public abstract class ParseFilter {

    /**
     * Called when parsing a specific page
     * 
     * @param URL
     *            the URL of the page being parsed
     * @param content
     *            the content being parsed
     * @param doc
     *            the DOM tree resulting of the parsing of the content or null
     *            if {@link #needsDOM()} returns <code>false</code>
     * @param parse
     *            the metadata to be updated with the resulting of the parsing
     */
    public abstract void filter(String URL, byte[] content,
            DocumentFragment doc, ParseResult parse);

    /**
     * Called when this filter is being initialized
     * 
     * @param stormConf
     *            The Storm configuration used for the parsing bolt
     * @param filterParams
     *            the filter specific configuration. Never null
     */
    public void configure(@SuppressWarnings("rawtypes") Map stormConf,
            JsonNode filterParams) {

    }

    /**
     * Specifies whether this filter requires a DOM representation of the
     * document
     * 
     * @return <code>true</code>if this needs a DOM representation of the
     *         document, <code>false</code> otherwise.
     */
    public boolean needsDOM() {
        return false;
    }

}