repositionableinputstream.html
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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>RepositionableInputStream 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"> RepositionableInputStream.java</em></em><a name="2" href="#2">2</a> <em class="comment"> *</em><a name="3" href="#3">3</a> <em class="comment"> * $Id: RepositionableInputStream.java 4826 2006-12-22 00:16:27Z stack-sf $</em><a name="4" href="#4">4</a> <em class="comment"> *</em><a name="5" href="#5">5</a> <em class="comment"> * Created Dec 20, 2005</em><a name="6" href="#6">6</a> <em class="comment"> *</em><a name="7" href="#7">7</a> <em class="comment"> * Copyright (C) 2005 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/io/package-summary.html">org.archive.io</a>;<a name="26" href="#26">26</a> <a name="27" href="#27">27</a> <strong>import</strong> it.unimi.dsi.fastutil.io.RepositionableStream;<a name="28" href="#28">28</a> <a name="29" href="#29">29</a> <strong>import</strong> java.io.BufferedInputStream;<a name="30" href="#30">30</a> <strong>import</strong> java.io.IOException;<a name="31" href="#31">31</a> <strong>import</strong> java.io.InputStream;<a name="32" href="#32">32</a> <a name="33" href="#33">33</a> <em>/**<em>*</em></em><a name="34" href="#34">34</a> <em> * Wrapper around an {@link InputStream} to make a primitive Repositionable</em><a name="35" href="#35">35</a> <em> * stream. Uses a {@link BufferedInputStream}. Calls mark on every read so</em><a name="36" href="#36">36</a> <em> * we'll remember at least the last thing read (You can only backup on the</em><a name="37" href="#37">37</a> <em> * last thing read -- not last 2 or 3 things read). Used by</em><a name="38" href="#38">38</a> <em> * {@link GzippedInputStream} when reading streams over a network. Wraps a</em><a name="39" href="#39">39</a> <em> * HTTP, etc., stream so we can back it up if needs be after the</em><a name="40" href="#40">40</a> <em> * GZIP inflater has done a fill of its full buffer though it only needed</em><a name="41" href="#41">41</a> <em> * the first few bytes to finish decompressing the current GZIP member.</em><a name="42" href="#42">42</a> <em> * </em><a name="43" href="#43">43</a> <em> * <p>TODO: More robust implementation. Tried to use the it.unimi.dsi.io</em><a name="44" href="#44">44</a> <em> * FastBufferdInputStream but relies on FileChannel ByteBuffers and if not</em><a name="45" href="#45">45</a> <em> * present -- as would be the case reading from a network stream, the main</em><a name="46" href="#46">46</a> <em> * application for this instance -- then it expects the underlying stream </em><a name="47" href="#47">47</a> <em> * implements RepositionableStream interface so chicken or egg problem.</em><a name="48" href="#48">48</a> <em> * @author stack</em><a name="49" href="#49">49</a> <em> */</em><a name="50" href="#50">50</a> <strong>public</strong> <strong>class</strong> <a href="../../../org/archive/io/RepositionableInputStream.html">RepositionableInputStream</a> <strong>extends</strong> BufferedInputStream implements<a name="51" href="#51">51</a> RepositionableStream {<a name="52" href="#52">52</a> <strong>private</strong> <strong>long</strong> position = 0;<a name="53" href="#53">53</a> <strong>private</strong> <strong>long</strong> markPosition = -1;<a name="54" href="#54">54</a> <a name="55" href="#55">55</a> <strong>public</strong> <a href="../../../org/archive/io/RepositionableInputStream.html">RepositionableInputStream</a>(InputStream in) {<a name="56" href="#56">56</a> <strong>super</strong>(in);<a name="57" href="#57">57</a> }<a name="58" href="#58">58</a> <a name="59" href="#59">59</a> <strong>public</strong> <a href="../../../org/archive/io/RepositionableInputStream.html">RepositionableInputStream</a>(InputStream in, <strong>int</strong> size) {<a name="60" href="#60">60</a> <strong>super</strong>(in, size);<a name="61" href="#61">61</a> }<a name="62" href="#62">62</a> <a name="63" href="#63">63</a> <strong>public</strong> <strong>int</strong> read(byte[] b) throws IOException {<a name="64" href="#64">64</a> <strong>int</strong> read = <strong>super</strong>.read(b);<a name="65" href="#65">65</a> <strong>if</strong> (read != -1) {<a name="66" href="#66">66</a> position += read;<a name="67" href="#67">67</a> }<a name="68" href="#68">68</a> <strong>return</strong> read;<a name="69" href="#69">69</a> }<a name="70" href="#70">70</a> <a name="71" href="#71">71</a> <strong>public</strong> <strong>synchronized</strong> <strong>int</strong> read(byte[] b, <strong>int</strong> offset, <strong>int</strong> ct)<a name="72" href="#72">72</a> throws IOException {<a name="73" href="#73">73</a> <em class="comment">// Mark the underlying stream so that we'll remember what we are about</em><a name="74" href="#74">74</a> <em class="comment">// to read unless a mark has been set in this RepositionableStream</em><a name="75" href="#75">75</a> <em class="comment">// (We have two levels of mark). In this latter case we want the</em><a name="76" href="#76">76</a> <em class="comment">// underlying stream to preserve its mark position so aligns with</em><a name="77" href="#77">77</a> <em class="comment">// this RS when eset is called.</em><a name="78" href="#78">78</a> <strong>if</strong> (!isMarked()) {<a name="79" href="#79">79</a> <strong>super</strong>.mark((ct > offset)? ct - offset: ct);<a name="80" href="#80">80</a> }<a name="81" href="#81">81</a> <strong>int</strong> read = <strong>super</strong>.read(b, offset, ct);<a name="82" href="#82">82</a> <strong>if</strong> (read != -1) {<a name="83" href="#83">83</a> position += read;<a name="84" href="#84">84</a> }<a name="85" href="#85">85</a> <strong>return</strong> read;<a name="86" href="#86">86</a> }<a name="87" href="#87">87</a> <a name="88" href="#88">88</a> <strong>public</strong> <strong>int</strong> read() throws IOException {<a name="89" href="#89">89</a> <em class="comment">// Mark the underlying stream so that we'll remember what we are about</em><a name="90" href="#90">90</a> <em class="comment">// to read unless a mark has been set in this RepositionableStream</em><a name="91" href="#91">91</a> <em class="comment">// (We have two levels of mark). In this latter case we want the</em><a name="92" href="#92">92</a> <em class="comment">// underlying stream to preserve its mark position so aligns with</em><a name="93" href="#93">93</a> <em class="comment">// this RS when eset is called.</em><a name="94" href="#94">94</a> <strong>if</strong> (!isMarked()) {<a name="95" href="#95">95</a> <strong>super</strong>.mark(1);<a name="96" href="#96">96</a> }<a name="97" href="#97">97</a> <strong>int</strong> c = <strong>super</strong>.read();<a name="98" href="#98">98</a> <strong>if</strong> (c != -1) {<a name="99" href="#99">99</a> position++;<a name="100" href="#100">100</a> }<a name="101" href="#101">101</a> <strong>return</strong> c;<a name="102" href="#102">102</a> }<a name="103" href="#103">103</a> <a name="104" href="#104">104</a> <strong>public</strong> <strong>void</strong> position(<strong>final</strong> <strong>long</strong> offset) {<a name="105" href="#105">105</a> <strong>if</strong> (<strong>this</strong>.position == offset) {<a name="106" href="#106">106</a> <strong>return</strong>;<a name="107" href="#107">107</a> }<a name="108" href="#108">108</a> <strong>int</strong> diff = (<strong>int</strong>)(offset - <strong>this</strong>.position);<a name="109" href="#109">109</a> <strong>long</strong> lowerBound = <strong>this</strong>.position - <strong>this</strong>.pos;<a name="110" href="#110">110</a> <strong>long</strong> upperBound = lowerBound + <strong>this</strong>.count;<a name="111" href="#111">111</a> <strong>if</strong> (offset < lowerBound || offset >= upperBound) {<a name="112" href="#112">112</a> <strong>throw</strong> <strong>new</strong> IllegalAccessError(<span class="string">"Offset goes outside "</span> +<a name="113" href="#113">113</a> <span class="string">"current this.buf (TODO: Do buffer fills if positive)"</span>);<a name="114" href="#114">114</a> }<a name="115" href="#115">115</a> <strong>this</strong>.position = offset;<a name="116" href="#116">116</a> <strong>this</strong>.pos += diff;<a name="117" href="#117">117</a> <em class="comment">// Clear any mark.</em><a name="118" href="#118">118</a> <strong>this</strong>.markPosition = -1;<a name="119" href="#119">119</a> }<a name="120" href="#120">120</a> <a name="121" href="#121">121</a> <strong>public</strong> <strong>void</strong> mark(<strong>int</strong> readlimit) {<a name="122" href="#122">122</a> <strong>this</strong>.markPosition = <strong>this</strong>.position;<a name="123" href="#123">123</a> <strong>super</strong>.mark(readlimit);<a name="124" href="#124">124</a> }<a name="125" href="#125">125</a> <a name="126" href="#126">126</a> <strong>public</strong> <strong>void</strong> reset() throws IOException {<a name="127" href="#127">127</a> <strong>super</strong>.reset();<a name="128" href="#128">128</a> <strong>this</strong>.position = <strong>this</strong>.markPosition;<a name="129" href="#129">129</a> <strong>this</strong>.markPosition = -1;<a name="130" href="#130">130</a> }<a name="131" href="#131">131</a> <a name="132" href="#132">132</a> <strong>protected</strong> <strong>boolean</strong> isMarked() {<a name="133" href="#133">133</a> <strong>return</strong> <strong>this</strong>.markPosition != -1;<a name="134" href="#134">134</a> }<a name="135" href="#135">135</a> <a name="136" href="#136">136</a> <strong>public</strong> <strong>long</strong> position() {<a name="137" href="#137">137</a> <strong>return</strong> <strong>this</strong>.position;<a name="138" href="#138">138</a> }<a name="139" href="#139">139</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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