changeevaluator.html

用JAVA编写的,在做实验的时候留下来的,本来想删的,但是传上来,大家分享吧

<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> &amp;&amp; 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> &amp;&amp; oldDigest != <strong>null</strong> 
<a name="104" href="#104">104</a>                     &amp;&amp; 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>