?? bufferedseekinputstream.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=UTF-8" /><title>BufferedSeekInputStream xref</title><link type="text/css" rel="stylesheet" href="../../../stylesheet.css" /></head><body><div id="overview"><a href="../../../../apidocs/org/archive/io/BufferedSeekInputStream.html">View Javadoc</a></div><pre><a name="1" href="#1">1</a> <em class="comment">/*<em class="comment"> BufferedSeekInputStream</em></em><a name="2" href="#2">2</a> <em class="comment">*</em><a name="3" href="#3">3</a> <em class="comment">* Created on September 14, 2006</em><a name="4" href="#4">4</a> <em class="comment">*</em><a name="5" href="#5">5</a> <em class="comment">* Copyright (C) 2006 Internet Archive.</em><a name="6" href="#6">6</a> <em class="comment">*</em><a name="7" href="#7">7</a> <em class="comment">* This file is part of the Heritrix web crawler (crawler.archive.org).</em><a name="8" href="#8">8</a> <em class="comment">*</em><a name="9" href="#9">9</a> <em class="comment">* Heritrix is free software; you can redistribute it and/or modify</em><a name="10" href="#10">10</a> <em class="comment">* it under the terms of the GNU Lesser Public License as published by</em><a name="11" href="#11">11</a> <em class="comment">* the Free Software Foundation; either version 2.1 of the License, or</em><a name="12" href="#12">12</a> <em class="comment">* any later version.</em><a name="13" href="#13">13</a> <em class="comment">*</em><a name="14" href="#14">14</a> <em class="comment">* Heritrix is distributed in the hope that it will be useful,</em><a name="15" href="#15">15</a> <em class="comment">* but WITHOUT ANY WARRANTY; without even the implied warranty of</em><a name="16" href="#16">16</a> <em class="comment">* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the</em><a name="17" href="#17">17</a> <em class="comment">* GNU Lesser Public License for more details.</em><a name="18" href="#18">18</a> <em class="comment">*</em><a name="19" href="#19">19</a> <em class="comment">* You should have received a copy of the GNU Lesser Public License</em><a name="20" href="#20">20</a> <em class="comment">* along with Heritrix; if not, write to the Free Software</em><a name="21" href="#21">21</a> <em class="comment">* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA</em><a name="22" href="#22">22</a> <em class="comment">*/</em><a name="23" href="#23">23</a> <strong>package</strong> <a href="../../../org/archive/io/package-summary.html">org.archive.io</a>;<a name="24" href="#24">24</a> <a name="25" href="#25">25</a> <a name="26" href="#26">26</a> <strong>import</strong> java.io.IOException;<a name="27" href="#27">27</a> <a name="28" href="#28">28</a> <a name="29" href="#29">29</a> <em>/**<em>*</em></em><a name="30" href="#30">30</a> <em> * Buffers data from some other SeekInputStream.</em><a name="31" href="#31">31</a> <em> * </em><a name="32" href="#32">32</a> <em> * @author pjack</em><a name="33" href="#33">33</a> <em> */</em><a name="34" href="#34">34</a> <strong>public</strong> <strong>class</strong> <a href="../../../org/archive/io/BufferedSeekInputStream.html">BufferedSeekInputStream</a> <strong>extends</strong> <a href="../../../org/archive/io/SeekInputStream.html">SeekInputStream</a> {<a name="35" href="#35">35</a> <a name="36" href="#36">36</a> <a name="37" href="#37">37</a> <em>/**<em>*</em></em><a name="38" href="#38">38</a> <em> * The underlying input stream.</em><a name="39" href="#39">39</a> <em> */</em><a name="40" href="#40">40</a> <strong>final</strong> <strong>private</strong> <a href="../../../org/archive/io/SeekInputStream.html">SeekInputStream</a> input;<a name="41" href="#41">41</a> <a name="42" href="#42">42</a> <a name="43" href="#43">43</a> <em>/**<em>*</em></em><a name="44" href="#44">44</a> <em> * The buffered data.</em><a name="45" href="#45">45</a> <em> */</em><a name="46" href="#46">46</a> <strong>final</strong> <strong>private</strong> byte[] buffer;<a name="47" href="#47">47</a> <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> * The maximum offset of valid data in the buffer. Usually the same</em><a name="51" href="#51">51</a> <em> * as buffer.length, but may be shorter if we're in the last region</em><a name="52" href="#52">52</a> <em> * of the stream.</em><a name="53" href="#53">53</a> <em> */</em><a name="54" href="#54">54</a> <strong>private</strong> <strong>int</strong> maxOffset;<a name="55" href="#55">55</a> <a name="56" href="#56">56</a> <a name="57" href="#57">57</a> <em>/**<em>*</em></em><a name="58" href="#58">58</a> <em> * The offset of within the buffer of the next byte to read.</em><a name="59" href="#59">59</a> <em> */</em><a name="60" href="#60">60</a> <strong>private</strong> <strong>int</strong> offset;<a name="61" href="#61">61</a> <a name="62" href="#62">62</a> <a name="63" href="#63">63</a> <em>/**<em>*</em></em><a name="64" href="#64">64</a> <em> * Constructor.</em><a name="65" href="#65">65</a> <em> * </em><a name="66" href="#66">66</a> <em> * @param input the underlying input stream</em><a name="67" href="#67">67</a> <em> * @param capacity the size of the buffer</em><a name="68" href="#68">68</a> <em> * @throws IOException if an IO occurs filling the first buffer</em><a name="69" href="#69">69</a> <em> */</em><a name="70" href="#70">70</a> <strong>public</strong> <a href="../../../org/archive/io/BufferedSeekInputStream.html">BufferedSeekInputStream</a>(<a href="../../../org/archive/io/SeekInputStream.html">SeekInputStream</a> input, <strong>int</strong> capacity) <a name="71" href="#71">71</a> throws IOException {<a name="72" href="#72">72</a> <strong>this</strong>.input = input;<a name="73" href="#73">73</a> <strong>this</strong>.buffer = <strong>new</strong> byte[capacity];<a name="74" href="#74">74</a> buffer();<a name="75" href="#75">75</a> }<a name="76" href="#76">76</a> <a name="77" href="#77">77</a> <em>/**<em>*</em></em><a name="78" href="#78">78</a> <em> * Fills the buffer.</em><a name="79" href="#79">79</a> <em> * </em><a name="80" href="#80">80</a> <em> * @throws IOException if an IO error occurs</em><a name="81" href="#81">81</a> <em> */</em><a name="82" href="#82">82</a> <strong>private</strong> <strong>void</strong> buffer() throws IOException {<a name="83" href="#83">83</a> <strong>int</strong> remaining = buffer.length;<a name="84" href="#84">84</a> <strong>while</strong> (remaining > 0) {<a name="85" href="#85">85</a> <strong>int</strong> r = input.read(buffer, buffer.length - remaining, remaining);<a name="86" href="#86">86</a> <strong>if</strong> (r <= 0) {<a name="87" href="#87">87</a> <em class="comment">// Not enough information to fill the buffer</em><a name="88" href="#88">88</a> offset = 0;<a name="89" href="#89">89</a> maxOffset = buffer.length - remaining;<a name="90" href="#90">90</a> <strong>return</strong>;<a name="91" href="#91">91</a> }<a name="92" href="#92">92</a> remaining -= r;<a name="93" href="#93">93</a> }<a name="94" href="#94">94</a> maxOffset = buffer.length;<a name="95" href="#95">95</a> offset = 0;<a name="96" href="#96">96</a> }<a name="97" href="#97">97</a> <a name="98" href="#98">98</a> <a name="99" href="#99">99</a> <em>/**<em>*</em></em><a name="100" href="#100">100</a> <em> * Ensures that the buffer is valid.</em><a name="101" href="#101">101</a> <em> * </em><a name="102" href="#102">102</a> <em> * @throws IOException if an IO error occurs</em><a name="103" href="#103">103</a> <em> */</em><a name="104" href="#104">104</a> <strong>private</strong> <strong>void</strong> ensureBuffer() throws IOException {<a name="105" href="#105">105</a> <strong>if</strong> (offset >= maxOffset) {<a name="106" href="#106">106</a> buffer();<a name="107" href="#107">107</a> }<a name="108" href="#108">108</a> }<a name="109" href="#109">109</a> ?? 快捷鍵說明
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