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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=UTF-8" /><title>Frontier xref</title><link type="text/css" rel="stylesheet" href="../../../../stylesheet.css" /></head><body><div id="overview"><a href="../../../../../apidocs/org/archive/crawler/framework/Frontier.html">View Javadoc</a></div><pre><a name="1" href="#1">1</a> <em class="comment">/*<em class="comment"> Frontier</em></em><a name="2" href="#2">2</a> <em class="comment"> *</em><a name="3" href="#3">3</a> <em class="comment"> * $Id: Frontier.java,v 1.14 2005/11/12 00:39:51 gojomo 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 Mar 29, 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 Internet Archive.</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/framework/package-summary.html">org.archive.crawler.framework</a>;<a name="26" href="#26">26</a> <a name="27" href="#27">27</a> <strong>import</strong> java.io.IOException;<a name="28" href="#28">28</a> <strong>import</strong> java.util.ArrayList;<a name="29" href="#29">29</a> <a name="30" href="#30">30</a> <strong>import</strong> org.archive.crawler.datamodel.CandidateURI;<a name="31" href="#31">31</a> <strong>import</strong> org.archive.crawler.datamodel.CrawlSubstats;<a name="32" href="#32">32</a> <strong>import</strong> org.archive.crawler.datamodel.CrawlURI;<a name="33" href="#33">33</a> <strong>import</strong> org.archive.crawler.framework.exceptions.EndedException;<a name="34" href="#34">34</a> <strong>import</strong> org.archive.crawler.framework.exceptions.FatalConfigurationException;<a name="35" href="#35">35</a> <strong>import</strong> org.archive.crawler.framework.exceptions.InvalidFrontierMarkerException;<a name="36" href="#36">36</a> <strong>import</strong> org.archive.crawler.frontier.FrontierJournal;<a name="37" href="#37">37</a> <strong>import</strong> org.archive.net.UURI;<a name="38" href="#38">38</a> <strong>import</strong> org.archive.util.Reporter;<a name="39" href="#39">39</a> <a name="40" href="#40">40</a> <a name="41" href="#41">41</a> <em>/**<em>*</em></em><a name="42" href="#42">42</a> <em> * An interface for URI Frontiers.</em><a name="43" href="#43">43</a> <em> *</em><a name="44" href="#44">44</a> <em> * <p>A URI Frontier is a pluggable module in Heritrix that maintains the</em><a name="45" href="#45">45</a> <em> * internal state of the crawl. This includes (but is not limited to):</em><a name="46" href="#46">46</a> <em> * <ul></em><a name="47" href="#47">47</a> <em> * <li>What URIs have been discovered</em><a name="48" href="#48">48</a> <em> * <li>What URIs are being processed (fetched)</em><a name="49" href="#49">49</a> <em> * <li>What URIs have been processed</em><a name="50" href="#50">50</a> <em> * <li>In what order unprocessed URIs will be processed</em><a name="51" href="#51">51</a> <em> * </ul></em><a name="52" href="#52">52</a> <em> *</em><a name="53" href="#53">53</a> <em> * <p>The Frontier is also responsible for enforcing any politeness restrictions</em><a name="54" href="#54">54</a> <em> * that may have been applied to the crawl. Such as limiting simultaneous</em><a name="55" href="#55">55</a> <em> * connection to the same host, server or IP number to 1 (or any other fixed</em><a name="56" href="#56">56</a> <em> * amount), delays between connections etc.</em><a name="57" href="#57">57</a> <em> *</em><a name="58" href="#58">58</a> <em> * <p>A URIFrontier is created by the</em><a name="59" href="#59">59</a> <em> * {@link org.archive.crawler.framework.CrawlController CrawlController} which</em><a name="60" href="#60">60</a> <em> * is in turn responsible for providing access to it. Most significant among</em><a name="61" href="#61">61</a> <em> * those modules interested in the Frontier are the</em><a name="62" href="#62">62</a> <em> * {@link org.archive.crawler.framework.ToeThread ToeThreads} who perform the</em><a name="63" href="#63">63</a> <em> * actual work of processing a URI.</em><a name="64" href="#64">64</a> <em> *</em><a name="65" href="#65">65</a> <em> * <p>The methods defined in this interface are those required to get URIs for</em><a name="66" href="#66">66</a> <em> * processing, report the results of processing back (ToeThreads) and to get</em><a name="67" href="#67">67</a> <em> * access to various statistical data along the way. The statistical data is</em><a name="68" href="#68">68</a> <em> * of interest to {@link org.archive.crawler.framework.StatisticsTracking</em><a name="69" href="#69">69</a> <em> * Statistics Tracking} modules. A couple of additional methods are provided</em><a name="70" href="#70">70</a> <em> * to be able to inspect and manipulate the Frontier at runtime.</em><a name="71" href="#71">71</a> <em> *</em><a name="72" href="#72">72</a> <em> * <p>The statistical data exposed by this interface is:</em><a name="73" href="#73">73</a> <em> * <ul></em><a name="74" href="#74">74</a> <em> * <li> {@link #discoveredUriCount() Discovered URIs}</em><a name="75" href="#75">75</a> <em> * <li> {@link #queuedUriCount() Queued URIs}</em><a name="76" href="#76">76</a> <em> * <li> {@link #finishedUriCount() Finished URIs}</em><a name="77" href="#77">77</a> <em> * <li> {@link #succeededFetchCount() Successfully processed URIs}</em><a name="78" href="#78">78</a> <em> * <li> {@link #failedFetchCount() Failed to process URIs}</em><a name="79" href="#79">79</a> <em> * <li> {@link #disregardedUriCount() Disregarded URIs}</em><a name="80" href="#80">80</a> <em> * <li> {@link #totalBytesWritten() Total bytes written}</em><a name="81" href="#81">81</a> <em> * </ul></em><a name="82" href="#82">82</a> <em> *</em><a name="83" href="#83">83</a> <em> * <p>In addition the frontier may optionally implement an interface that</em><a name="84" href="#84">84</a> <em> * exposes information about hosts.</em><a name="85" href="#85">85</a> <em> *</em><a name="86" href="#86">86</a> <em> * <p>Furthermore any implementation of the URI Frontier should trigger</em><a name="87" href="#87">87</a> <em> * {@link org.archive.crawler.event.CrawlURIDispositionListener</em><a name="88" href="#88">88</a> <em> * CrawlURIDispostionEvents} by invoking the proper methods on the</em><a name="89" href="#89">89</a> <em> * {@link org.archive.crawler.framework.CrawlController CrawlController}.</em><a name="90" href="#90">90</a> <em> * Doing this allows a custom built</em><a name="91" href="#91">91</a> <em> * {@link org.archive.crawler.framework.StatisticsTracking</em><a name="92" href="#92">92</a> <em> * Statistics Tracking} module to gather any other additional data it might be</em><a name="93" href="#93">93</a> <em> * interested in by examining the completed URIs.</em><a name="94" href="#94">94</a> <em> *</em><a name="95" href="#95">95</a> <em> * <p>All URI Frontiers inherit from</em><a name="96" href="#96">96</a> <em> * {@link org.archive.crawler.settings.ModuleType ModuleType}</em><a name="97" href="#97">97</a> <em> * and therefore creating settings follows the usual pattern of pluggable modules</em><a name="98" href="#98">98</a> <em> * in Heritrix.</em><a name="99" href="#99">99</a> <em> *</em><a name="100" href="#100">100</a> <em> * @author Gordon Mohr</em><a name="101" href="#101">101</a> <em> * @author Kristinn Sigurdsson</em><a name="102" href="#102">102</a> <em> *</em><a name="103" href="#103">103</a> <em> * @see org.archive.crawler.framework.CrawlController</em><a name="104" href="#104">104</a> <em> * @see org.archive.crawler.framework.CrawlController#fireCrawledURIDisregardEvent(CrawlURI)</em><a name="105" href="#105">105</a> <em> * @see org.archive.crawler.framework.CrawlController#fireCrawledURIFailureEvent(CrawlURI)</em><a name="106" href="#106">106</a> <em> * @see org.archive.crawler.framework.CrawlController#fireCrawledURINeedRetryEvent(CrawlURI)</em><a name="107" href="#107">107</a> <em> * @see org.archive.crawler.framework.CrawlController#fireCrawledURISuccessfulEvent(CrawlURI)</em><a name="108" href="#108">108</a> <em> * @see org.archive.crawler.framework.StatisticsTracking</em><a name="109" href="#109">109</a> <em> * @see org.archive.crawler.framework.ToeThread</em><a name="110" href="#110">110</a> <em> * @see org.archive.crawler.framework.FrontierHostStatistics</em><a name="111" href="#111">111</a> <em> * @see org.archive.crawler.settings.ModuleType</em><a name="112" href="#112">112</a> <em> */</em><a name="113" href="#113">113</a> <strong>public</strong> <strong>interface</strong> <a href="../../../../org/archive/crawler/framework/Frontier.html">Frontier</a> <strong>extends</strong> <a href="../../../../org/archive/util/Reporter.html">Reporter</a> {<a name="114" href="#114">114</a> <em>/**<em>*</em></em><a name="115" href="#115">115</a> <em> * All URI Frontiers should have the same 'name' attribute. This constant</em><a name="116" href="#116">116</a> <em> * defines that name. This is a name used to reference the Frontier being</em><a name="117" href="#117">117</a> <em> * used in a given crawl order and since there can only be one Frontier</em><a name="118" href="#118">118</a> <em> * per crawl order a fixed, unique name for Frontiers is optimal.</em><a name="119" href="#119">119</a> <em> *</em><a name="120" href="#120">120</a> <em> * @see org.archive.crawler.settings.ModuleType#ModuleType(String)</em><a name="121" href="#121">121</a> <em> */</em><a name="122" href="#122">122</a> <strong>public</strong> <strong>static</strong> <strong>final</strong> String ATTR_NAME = <span class="string">"frontier"</span>;<a name="123" href="#123">123</a> <a name="124" href="#124">124</a> <em>/**<em>*</em></em><a name="125" href="#125">125</a> <em> * Initialize the Frontier.</em><a name="126" href="#126">126</a> <em> *</em><a name="127" href="#127">127</a> <em> * <p> This method is invoked by the CrawlController once it has</em><a name="128" href="#128">128</a> <em> * created the Frontier. The constructor of the Frontier should</em><a name="129" href="#129">129</a> <em> * only contain code for setting up it's settings framework. This</em><a name="130" href="#130">130</a> <em> * method should contain all other 'startup' code.</em><a name="131" href="#131">131</a> <em> *</em><a name="132" href="#132">132</a> <em> * @param c The CrawlController that created the Frontier.</em><a name="133" href="#133">133</a> <em> *</em><a name="134" href="#134">134</a> <em> * @throws FatalConfigurationException If provided settings are illegal or</em><a name="135" href="#135">135</a> <em> * otherwise unusable.</em><a name="136" href="#136">136</a> <em> * @throws IOException If there is a problem reading settings or seeds file</em><a name="137" href="#137">137</a> <em> * from disk.</em><a name="138" href="#138">138</a> <em> */</em><a name="139" href="#139">139</a> <strong>public</strong> <strong>void</strong> initialize(<a href="../../../../org/archive/crawler/framework/CrawlController.html">CrawlController</a> c)<a name="140" href="#140">140</a> throws FatalConfigurationException, IOException;<a name="141" href="#141">141</a> <a name="142" href="#142">142</a> <em>/**<em>*</em></em><a name="143" href="#143">143</a> <em> * Get the next URI that should be processed. If no URI becomes availible</em><a name="144" href="#144">144</a> <em> * during the time specified null will be returned.</em><a name="145" href="#145">145</a> <em> *</em><a name="146" href="#146">146</a> <em> * @return the next URI that should be processed.</em><a name="147" href="#147">147</a> <em> * @throws InterruptedException</em><a name="148" href="#148">148</a> <em> * @throws EndedException </em><a name="149" href="#149">149</a> <em> */</em><a name="150" href="#150">150</a> <a href="../../../../org/archive/crawler/datamodel/CrawlURI.html">CrawlURI</a> next() throws InterruptedException, EndedException;<a name="151" href="#151">151</a> ⌨️ 快捷键说明
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