    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[0-9]*' 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: 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: 2006-09-18 20:32:47 +0000 (Mon, 18 Sep 2006) $, $Revision: 4634 $
    37   */
    38  public class StripWWWNRule extends BaseRule {
    39      private static final long serialVersionUID = 3619916990307308590L;
    40
    41      private static final String DESCRIPTION = "Strip any 'www[0-9]*' found. " +
    42          "Use this rule to equate 'http://www.archive.org/index.html' and " +
    43          "'http://www0001.archive.org/index.html' with " +
    44          "'http://archive.org/index.html'.  The resulting canonicalization " +
    45          "returns 'http://archive.org/index.html'.  It removes any www's " +
    46          "or wwwNNN's found, where 'N' is one or more numerics, EXCEPT " +
    47          "on URIs that have no path/query component " +
    48          ". Top-level 'slash page' URIs are left unstripped: we prefer " +
    49          "crawling redundant top pages to missing an entire site only " +
    50          "available from either the www-full or www-less hostname, but not " +
    51          "both.  Operates on http and https schemes only. " +
    52          "Use StripWWWRule to strip a lone 'www' only (This rule is a " +
    53          "more general version of StripWWWRule).";
    54
    55      private static final Pattern REGEX =
    56          Pattern.compile("(?i)^(https?://)(?:www[0-9]*//.)([^/]*/.+)$");
    57
    58      public StripWWWNRule(String name) {
    59          super(name, DESCRIPTION);
    60      }
    61
    62      public String canonicalize(String url, Object context) {
    63          return doStripRegexMatch(url, REGEX.matcher(url));
    64      }
    65  }