urlnormalizerfactory.java

nutch0.8源码

/**
 * Copyright 2005 The Apache Software Foundation
 *
 * 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 org.apache.nutch.net;

// Commons Logging imports
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.apache.hadoop.conf.*;


/** Factory to create a UrlNormalizer from "urlnormalizer.class" config property. */
public class UrlNormalizerFactory {
  private static final Log LOG = LogFactory.getLog(UrlNormalizerFactory.class);

  private Configuration conf;

  public UrlNormalizerFactory(Configuration conf) {
    this.conf = conf;
  }

  /** Return the default UrlNormalizer implementation. */
  public UrlNormalizer getNormalizer() {
    String urlNormalizer = null;
    UrlNormalizer normalizer = (UrlNormalizer) this.conf
        .getObject(UrlNormalizer.class.getName());
    if (normalizer == null) {
      try {
        urlNormalizer = this.conf.get("urlnormalizer.class");
        if (LOG.isInfoEnabled()) {
          LOG.info("Using URL normalizer: " + urlNormalizer);
        }
        Class normalizerClass = Class.forName(urlNormalizer);
        normalizer = (UrlNormalizer) normalizerClass.newInstance();
        normalizer.setConf(this.conf);
        this.conf.setObject(UrlNormalizer.class.getName(), normalizer);
      } catch (Exception e) {
        throw new RuntimeException("Couldn't create " + urlNormalizer, e);
      }
    }
    return normalizer;
  }
}