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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head><meta http-equiv="content-type" content="text/html; charset=ISO-8859-1" /><title>ChangeEvaluator xref</title><link type="text/css" rel="stylesheet" href="../../../../stylesheet.css" /></head><body><pre><a name="1" href="#1">1</a> <em class="comment">/*<em class="comment"> ChangeEvaluator</em></em><a name="2" href="#2">2</a> <em class="comment"> * </em><a name="3" href="#3">3</a> <em class="comment"> * $Id: ChangeEvaluator.java,v 1.4 2005/04/20 14:59:47 kristinn_sig Exp $</em><a name="4" href="#4">4</a> <em class="comment"> * </em><a name="5" href="#5">5</a> <em class="comment"> * Created on 11.11.2004</em><a name="6" href="#6">6</a> <em class="comment"> *</em><a name="7" href="#7">7</a> <em class="comment"> * Copyright (C) 2004 Kristinn Sigurdsson.</em><a name="8" href="#8">8</a> <em class="comment"> * </em><a name="9" href="#9">9</a> <em class="comment"> * This file is part of the Heritrix web crawler (crawler.archive.org).</em><a name="10" href="#10">10</a> <em class="comment"> * </em><a name="11" href="#11">11</a> <em class="comment"> * Heritrix is free software; you can redistribute it and/or modify</em><a name="12" href="#12">12</a> <em class="comment"> * it under the terms of the GNU Lesser Public License as published by</em><a name="13" href="#13">13</a> <em class="comment"> * the Free Software Foundation; either version 2.1 of the License, or</em><a name="14" href="#14">14</a> <em class="comment"> * any later version.</em><a name="15" href="#15">15</a> <em class="comment"> * </em><a name="16" href="#16">16</a> <em class="comment"> * Heritrix is distributed in the hope that it will be useful, </em><a name="17" href="#17">17</a> <em class="comment"> * but WITHOUT ANY WARRANTY; without even the implied warranty of</em><a name="18" href="#18">18</a> <em class="comment"> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the</em><a name="19" href="#19">19</a> <em class="comment"> * GNU Lesser Public License for more details.</em><a name="20" href="#20">20</a> <em class="comment"> * </em><a name="21" href="#21">21</a> <em class="comment"> * You should have received a copy of the GNU Lesser Public License</em><a name="22" href="#22">22</a> <em class="comment"> * along with Heritrix; if not, write to the Free Software</em><a name="23" href="#23">23</a> <em class="comment"> * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA</em><a name="24" href="#24">24</a> <em class="comment"> */</em><a name="25" href="#25">25</a> <strong>package</strong> <a href="../../../../org/archive/crawler/extractor/package-summary.html">org.archive.crawler.extractor</a>;<a name="26" href="#26">26</a> <a name="27" href="#27">27</a> <strong>import</strong> java.util.logging.Level;<a name="28" href="#28">28</a> <strong>import</strong> java.util.logging.Logger;<a name="29" href="#29">29</a> <a name="30" href="#30">30</a> <strong>import</strong> org.archive.crawler.datamodel.CrawlURI;<a name="31" href="#31">31</a> <strong>import</strong> org.archive.crawler.framework.Processor;<a name="32" href="#32">32</a> <strong>import</strong> org.archive.crawler.frontier.AdaptiveRevisitAttributeConstants;<a name="33" href="#33">33</a> <strong>import</strong> org.archive.util.Base32;<a name="34" href="#34">34</a> <a name="35" href="#35">35</a> <em>/**<em>*</em></em><a name="36" href="#36">36</a> <em> * This processor compares the CrawlURI's current </em><a name="37" href="#37">37</a> <em> * {@link org.archive.crawler.datamodel.CrawlURI#getContentDigest() content digest}</em><a name="38" href="#38">38</a> <em> * with the one from a previous crawl. If they are equal, then further </em><a name="39" href="#39">39</a> <em> * processing is skipped (going straight to the post processor chain) and the</em><a name="40" href="#40">40</a> <em> * CrawlURI is marked appropriately.</em><a name="41" href="#41">41</a> <em> *</em><a name="42" href="#42">42</a> <em> * @author Kristinn Sigurdsson</em><a name="43" href="#43">43</a> <em> */</em><a name="44" href="#44">44</a> <strong>public</strong> <strong>class</strong> <a href="../../../../org/archive/crawler/extractor/ChangeEvaluator.html">ChangeEvaluator</a> <strong>extends</strong> <a href="../../../../org/archive/crawler/framework/Processor.html">Processor</a><a name="45" href="#45">45</a> implements <a href="../../../../org/archive/crawler/frontier/AdaptiveRevisitAttributeConstants.html">AdaptiveRevisitAttributeConstants</a> {<a name="46" href="#46">46</a> <strong>private</strong> <strong>static</strong> <strong>final</strong> Logger logger =<a name="47" href="#47">47</a> Logger.getLogger(ChangeEvaluator.<strong>class</strong>.getName());<a name="48" href="#48">48</a> <a name="49" href="#49">49</a> <em>/**<em>*</em></em><a name="50" href="#50">50</a> <em> * Constructor</em><a name="51" href="#51">51</a> <em> * @param name The name of the module</em><a name="52" href="#52">52</a> <em> */</em><a name="53" href="#53">53</a> <strong>public</strong> <a href="../../../../org/archive/crawler/extractor/ChangeEvaluator.html">ChangeEvaluator</a>(String name) {<a name="54" href="#54">54</a> <strong>super</strong>(name, <span class="string">"Compares CrawlURI's current "</span> +<a name="55" href="#55">55</a> <span class="string">"content digest with digest from previous crawl. If "</span> +<a name="56" href="#56">56</a> <span class="string">"equal, further processing is skipped (going "</span> +<a name="57" href="#57">57</a> <span class="string">"straight to the post processor chain) and the CrawlURI is "</span> +<a name="58" href="#58">58</a> <span class="string">"marked appropriately. Should be located at the start of "</span> +<a name="59" href="#59">59</a> <span class="string">"the Extractor chain."</span>);<a name="60" href="#60">60</a> <a name="61" href="#61">61</a> <em class="comment">// Register persistent CrawlURI items </em><a name="62" href="#62">62</a> CrawlURI.addAlistPersistentMember(A_LAST_CONTENT_DIGEST);<a name="63" href="#63">63</a> CrawlURI.addAlistPersistentMember(A_NUMBER_OF_VISITS);<a name="64" href="#64">64</a> CrawlURI.addAlistPersistentMember(A_NUMBER_OF_VERSIONS);<a name="65" href="#65">65</a> }<a name="66" href="#66">66</a> <a name="67" href="#67">67</a> <strong>protected</strong> <strong>void</strong> innerProcess(<a href="../../../../org/archive/crawler/datamodel/CrawlURI.html">CrawlURI</a> curi) throws InterruptedException {<a name="68" href="#68">68</a> <strong>if</strong> (curi.isSuccess() == false) {<a name="69" href="#69">69</a> <em class="comment">// Early return. No point in doing comparison on failed downloads.</em><a name="70" href="#70">70</a> <strong>if</strong> (logger.isLoggable(Level.FINEST)) {<a name="71" href="#71">71</a> logger.finest(<span class="string">"Not handling "</span> + curi.toString()<a name="72" href="#72">72</a> + <span class="string">", did not "</span> + <span class="string">"succeed."</span>);<a name="73" href="#73">73</a> }<a name="74" href="#74">74</a> <strong>return</strong>;<a name="75" href="#75">75</a> }<a name="76" href="#76">76</a> <a name="77" href="#77">77</a> <em class="comment">// If a mid fetch filter aborts the HTTP fetch because the headers</em><a name="78" href="#78">78</a> <em class="comment">// predict no change, we can skip the whole comparing hashes.</em><a name="79" href="#79">79</a> <strong>if</strong> (!curi.containsKey(A_CONTENT_STATE_KEY) ||<a name="80" href="#80">80</a> curi.getInt(A_CONTENT_STATE_KEY) != CONTENT_UNCHANGED) {<a name="81" href="#81">81</a> String currentDigest = <strong>null</strong>;<a name="82" href="#82">82</a> Object digest = curi.getContentDigest();<a name="83" href="#83">83</a> <strong>if</strong> (digest != <strong>null</strong>) {<a name="84" href="#84">84</a> currentDigest = Base32.encode((byte[])digest);<a name="85" href="#85">85</a> }<a name="86" href="#86">86</a> <a name="87" href="#87">87</a> String oldDigest = <strong>null</strong>;<a name="88" href="#88">88</a> <strong>if</strong> (curi.containsKey(A_LAST_CONTENT_DIGEST)) {<a name="89" href="#89">89</a> oldDigest = curi.getString(A_LAST_CONTENT_DIGEST);<a name="90" href="#90">90</a> }<a name="91" href="#91">91</a> <a name="92" href="#92">92</a> <em class="comment">// Compare the String representation of the byte arrays.</em><a name="93" href="#93">93</a> <strong>if</strong> (currentDigest == <strong>null</strong> && oldDigest == <strong>null</strong>) {<a name="94" href="#94">94</a> <em class="comment">// Both are null, can't do a thing</em><a name="95" href="#95">95</a> <strong>if</strong> (logger.isLoggable(Level.FINER)) {<a name="96" href="#96">96</a> logger.finer(<span class="string">"On "</span> + curi.toString()<a name="97" href="#97">97</a> + <span class="string">" both digest are null"</span>);<a name="98" href="#98">98</a> }<a name="99" href="#99">99</a> <em class="comment">// NOTE! RETURN!</em><a name="100" href="#100">100</a> <strong>return</strong>;<a name="101" href="#101">101</a> }<a name="102" href="#102">102</a> <a name="103" href="#103">103</a> <strong>if</strong> (currentDigest != <strong>null</strong> && oldDigest != <strong>null</strong> <a name="104" href="#104">104</a> && currentDigest.equals(oldDigest)) { <a name="105" href="#105">105</a> <em class="comment">// If equal, we have just downloaded a duplicate.</em><a name="106" href="#106">106</a> <strong>if</strong> (logger.isLoggable(Level.FINER)) {<a name="107" href="#107">107</a> logger.finer(<span class="string">"On "</span> + curi.toString()<a name="108" href="#108">108</a> + <span class="string">" both digest are "</span> + <span class="string">"equal. Old: "</span> + oldDigest<a name="109" href="#109">109</a> + <span class="string">", new: "</span> + currentDigest);<a name="110" href="#110">110</a> }<a name="111" href="#111">111</a> curi.putInt(A_CONTENT_STATE_KEY, CONTENT_UNCHANGED);<a name="112" href="#112">112</a> <em class="comment">// TODO: In the future processors should take note of the content</em><a name="113" href="#113">113</a> <em class="comment">// state, removing the need for the following 'skip'</em><a name="114" href="#114">114</a> curi.skipToProcessorChain(getController().getPostprocessorChain());<a name="115" href="#115">115</a> <em class="comment">// Make not in log</em><a name="116" href="#116">116</a> curi.addAnnotation(<span class="string">"unchanged"</span>);<a name="117" href="#117">117</a> <em class="comment">// Set content size to zero, we are not going to 'write it to disk'</em><a name="118" href="#118">118</a> curi.setContentSize(0);<a name="119" href="#119">119</a> } <strong>else</strong> {<a name="120" href="#120">120</a> <em class="comment">// Document has changed</em><a name="121" href="#121">121</a> <strong>if</strong> (logger.isLoggable(Level.FINER)) {<a name="122" href="#122">122</a> logger.finer(<span class="string">"On "</span> + curi.toString()<a name="123" href="#123">123</a> + <span class="string">" digest are not "</span> + <span class="string">"equal. Old: "</span><a name="124" href="#124">124</a> + (oldDigest == <strong>null</strong>? <span class="string">"null"</span>: oldDigest)<a name="125" href="#125">125</a> + <span class="string">", new: "</span><a name="126" href="#126">126</a> + (currentDigest == <strong>null</strong>? <span class="string">"null"</span>: currentDigest));<a name="127" href="#127">127</a> }<a name="128" href="#128">128</a> <em class="comment">// currentDigest may be null, that probably means a failed download</em><a name="129" href="#129">129</a> curi.putInt(A_CONTENT_STATE_KEY, CONTENT_CHANGED);<a name="130" href="#130">130</a> curi.putString(A_LAST_CONTENT_DIGEST, currentDigest); <a name="131" href="#131">131</a> }<a name="132" href="#132">132</a> } <strong>else</strong> {<a name="133" href="#133">133</a> <strong>if</strong> (logger.isLoggable(Level.FINER)) {<a name="134" href="#134">134</a> logger.finer(<span class="string">"On "</span> + curi.toString()<a name="135" href="#135">135</a> + <span class="string">" content state was "</span> + <span class="string">"already set as UNCHANGED."</span>);<a name="136" href="#136">136</a> }<a name="137" href="#137">137</a> }<a name="138" href="#138">138</a> <a name="139" href="#139">139</a> <em class="comment">// Update visit and version counters</em><a name="140" href="#140">140</a> <strong>int</strong> visits = 1;<a name="141" href="#141">141</a> <strong>if</strong>(curi.containsKey(A_NUMBER_OF_VISITS)) {<a name="142" href="#142">142</a> visits = curi.getInt(A_NUMBER_OF_VISITS) + 1;<a name="143" href="#143">143</a> }<a name="144" href="#144">144</a> curi.putInt(A_NUMBER_OF_VISITS, visits);<a name="145" href="#145">145</a> <a name="146" href="#146">146</a> <em class="comment">// Update versions.</em><a name="147" href="#147">147</a> <strong>if</strong>(curi.getInt(A_CONTENT_STATE_KEY) == CONTENT_CHANGED) {<a name="148" href="#148">148</a> <strong>int</strong> versions = 1;<a name="149" href="#149">149</a> <strong>if</strong>(curi.containsKey(A_NUMBER_OF_VERSIONS)) {<a name="150" href="#150">150</a> versions = curi.getInt(A_NUMBER_OF_VERSIONS) + 1;<a name="151" href="#151">151</a> }<a name="152" href="#152">152</a> curi.putInt(A_NUMBER_OF_VERSIONS,versions);<a name="153" href="#153">153</a> }<a name="154" href="#154">154</a> }<a name="155" href="#155">155</a> }</pre><hr/><div id="footer">This page was automatically generated by <a href="http://maven.apache.org/">Maven</a></div></body></html>⌨️ 快捷键说明
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