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    1   /* StripWWWRule
    2    *
    3    * Created on Oct 5, 2004
    4    *
    5    * Copyright (C) 2004 Internet Archive.
    6    *
    7    * This file is part of the Heritrix web crawler (crawler.archive.org).
    8    *
    9    * Heritrix is free software; you can redistribute it and/or modify
    10   * it under the terms of the GNU Lesser Public License as published by
    11   * the Free Software Foundation; either version 2.1 of the License, or
    12   * any later version.
    13   *
    14   * Heritrix is distributed in the hope that it will be useful,
    15   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    16   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    17   * GNU Lesser Public License for more details.
    18   *
    19   * You should have received a copy of the GNU Lesser Public License
    20   * along with Heritrix; if not, write to the Free Software
    21   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    22   */
    23  package org.archive.crawler.url.canonicalize;
    24
    25  import java.util.regex.Pattern;
    26
    27
    28
    29  /***
    30   * Strip any 'www' found on http/https URLs, IF they have some
    31   * path/query component (content after third slash). (Top 'slash page'
    32   * URIs are left unstripped, so that we prefer crawling redundant
    33   * top pages to missing an entire site only available from either
    34   * the www-full or www-less hostname, but not both).
    35   * @author stack
    36   * @version $Date: 2006-09-25 20:27:35 +0000 (Mon, 25 Sep 2006) $, $Revision: 4655 $
    37   */
    38  public class StripWWWRule extends BaseRule {
    39
    40      private static final long serialVersionUID = -5416391108485746976L;
    41
    42      private static final String DESCRIPTION = "Strip any 'www' found. " +
    43          "Use this rule to equate 'http://www.archive.org/index.html' and" +
    44          " 'http://archive.org/index.html'. The resulting canonicalization" +
    45          " returns 'http://archive.org/index.html'.  It removes any www's " +
    46          "found, except on URIs that have no path/query component " +
    47          "('slash' pages).  Operates on http and https schemes only. " +
    48          "Use the more general StripWWWNRule if you want to strip both 'www' " +
    49          "and 'www01', 'www02', etc.";
    50
    51      private static final Pattern REGEX =
    52          Pattern.compile("(?i)^(https?://)(?:www//.)([^/]*/.+)$");
    53
    54      public StripWWWRule(String name) {
    55          super(name, DESCRIPTION);
    56      }
    57
    58      public String canonicalize(String url, Object context) {
    59          return doStripRegexMatch(url, REGEX.matcher(url));
    60      }
    61  }