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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>Base32 xref</title><link type="text/css" rel="stylesheet" href="../../../stylesheet.css" /></head><body><div id="overview"><a href="../../../../apidocs/org/archive/util/Base32.html">View Javadoc</a></div><pre><a name="1" href="#1">1</a> <em class="comment">/*<em class="comment"> Base32</em></em><a name="2" href="#2">2</a> <em class="comment">*</em><a name="3" href="#3">3</a> <em class="comment">* $Id: Base32.java 1828 2004-04-15 19:04:01Z 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 on Jan 21, 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/util/package-summary.html">org.archive.util</a>;<a name="26" href="#26">26</a> <a name="27" href="#27">27</a> <em>/**<em>*</em></em><a name="28" href="#28">28</a> <em> * Base32 - encodes and decodes RFC3548 Base32</em><a name="29" href="#29">29</a> <em> * (see <a href="http://www.faqs.org/rfcs/rfc3548.html" target="alexandria_uri">http://www.faqs.org/rfcs/rfc3548.html</a> )</em><a name="30" href="#30">30</a> <em> *</em><a name="31" href="#31">31</a> <em> * Imported public-domain code of Bitzi.</em><a name="32" href="#32">32</a> <em> *</em><a name="33" href="#33">33</a> <em> * @author Robert Kaye</em><a name="34" href="#34">34</a> <em> * @author Gordon Mohr</em><a name="35" href="#35">35</a> <em> */</em><a name="36" href="#36">36</a> <strong>public</strong> <strong>class</strong> Base32 {<a name="37" href="#37">37</a> <strong>private</strong> <strong>static</strong> <strong>final</strong> String base32Chars =<a name="38" href="#38">38</a> <span class="string">"ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"</span>;<a name="39" href="#39">39</a> <strong>private</strong> <strong>static</strong> <strong>final</strong> <strong>int</strong>[] base32Lookup =<a name="40" href="#40">40</a> { 0xFF,0xFF,0x1A,0x1B,0x1C,0x1D,0x1E,0x1F, <em class="comment">// '0', '1', '2', '3', '4', '5', '6', '7'</em><a name="41" href="#41">41</a> 0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF, <em class="comment">// '8', '9', ':', ';', '<', '=', '>', '?'</em><a name="42" href="#42">42</a> 0xFF,0x00,0x01,0x02,0x03,0x04,0x05,0x06, <em class="comment">// '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G'</em><a name="43" href="#43">43</a> 0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E, <em class="comment">// 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O'</em><a name="44" href="#44">44</a> 0x0F,0x10,0x11,0x12,0x13,0x14,0x15,0x16, <em class="comment">// 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W'</em><a name="45" href="#45">45</a> 0x17,0x18,0x19,0xFF,0xFF,0xFF,0xFF,0xFF, <em class="comment">// 'X', 'Y', 'Z', '[', '\', ']', '^', '_'</em><a name="46" href="#46">46</a> 0xFF,0x00,0x01,0x02,0x03,0x04,0x05,0x06, <em class="comment">// '`', 'a', 'b', 'c', 'd', 'e', 'f', 'g'</em><a name="47" href="#47">47</a> 0x07,0x08,0x09,0x0A,0x0B,0x0C,0x0D,0x0E, <em class="comment">// 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o'</em><a name="48" href="#48">48</a> 0x0F,0x10,0x11,0x12,0x13,0x14,0x15,0x16, <em class="comment">// 'p', 'q', 'r', 's', 't', 'u', 'v', 'w'</em><a name="49" href="#49">49</a> 0x17,0x18,0x19,0xFF,0xFF,0xFF,0xFF,0xFF <em class="comment">// 'x', 'y', 'z', '{', '|', '}', '~', 'DEL'</em><a name="50" href="#50">50</a> };<a name="51" href="#51">51</a> <a name="52" href="#52">52</a> <em>/**<em>*</em></em><a name="53" href="#53">53</a> <em> * Encodes byte array to Base32 String.</em><a name="54" href="#54">54</a> <em> *</em><a name="55" href="#55">55</a> <em> * @param bytes Bytes to encode.</em><a name="56" href="#56">56</a> <em> * @return Encoded byte array <code>bytes</code> as a String.</em><a name="57" href="#57">57</a> <em> *</em><a name="58" href="#58">58</a> <em> */</em><a name="59" href="#59">59</a> <strong>static</strong> <strong>public</strong> String encode(<strong>final</strong> byte[] bytes) {<a name="60" href="#60">60</a> <strong>int</strong> i = 0, index = 0, digit = 0;<a name="61" href="#61">61</a> <strong>int</strong> currByte, nextByte;<a name="62" href="#62">62</a> StringBuffer base32 = <strong>new</strong> StringBuffer((bytes.length + 7) * 8 / 5);<a name="63" href="#63">63</a> <a name="64" href="#64">64</a> <strong>while</strong> (i < bytes.length) {<a name="65" href="#65">65</a> currByte = (bytes[i] >= 0) ? bytes[i] : (bytes[i] + 256); <em class="comment">// unsign</em><a name="66" href="#66">66</a> <a name="67" href="#67">67</a> <em class="comment">/*<em class="comment"> Is the current digit going to span a byte boundary? */</em></em><a name="68" href="#68">68</a> <strong>if</strong> (index > 3) {<a name="69" href="#69">69</a> <strong>if</strong> ((i + 1) < bytes.length) {<a name="70" href="#70">70</a> nextByte =<a name="71" href="#71">71</a> (bytes[i + 1] >= 0) ? bytes[i + 1] : (bytes[i + 1] + 256);<a name="72" href="#72">72</a> } <strong>else</strong> {<a name="73" href="#73">73</a> nextByte = 0;<a name="74" href="#74">74</a> }<a name="75" href="#75">75</a> <a name="76" href="#76">76</a> digit = currByte & (0xFF >> index);<a name="77" href="#77">77</a> index = (index + 5) % 8;<a name="78" href="#78">78</a> digit <<= index;<a name="79" href="#79">79</a> digit |= nextByte >> (8 - index);<a name="80" href="#80">80</a> i++;<a name="81" href="#81">81</a> } <strong>else</strong> {<a name="82" href="#82">82</a> digit = (currByte >> (8 - (index + 5))) & 0x1F;<a name="83" href="#83">83</a> index = (index + 5) % 8;<a name="84" href="#84">84</a> <strong>if</strong> (index == 0)<a name="85" href="#85">85</a> i++;<a name="86" href="#86">86</a> }<a name="87" href="#87">87</a> base32.append(base32Chars.charAt(digit));<a name="88" href="#88">88</a> }<a name="89" href="#89">89</a> <a name="90" href="#90">90</a> <strong>return</strong> base32.toString();<a name="91" href="#91">91</a> }<a name="92" href="#92">92</a> <a name="93" href="#93">93</a> <em>/**<em>*</em></em><a name="94" href="#94">94</a> <em> * Decodes the given Base32 String to a raw byte array.</em><a name="95" href="#95">95</a> <em> *</em><a name="96" href="#96">96</a> <em> * @param base32</em><a name="97" href="#97">97</a> <em> * @return Decoded <code>base32</code> String as a raw byte array.</em><a name="98" href="#98">98</a> <em> */</em><a name="99" href="#99">99</a> <strong>static</strong> <strong>public</strong> byte[] decode(<strong>final</strong> String base32) {<a name="100" href="#100">100</a> <strong>int</strong> i, index, lookup, offset, digit;<a name="101" href="#101">101</a> byte[] bytes = <strong>new</strong> byte[base32.length() * 5 / 8];<a name="102" href="#102">102</a> <a name="103" href="#103">103</a> <strong>for</strong> (i = 0, index = 0, offset = 0; i < base32.length(); i++) {<a name="104" href="#104">104</a> lookup = base32.charAt(i) - '0';<a name="105" href="#105">105</a> <a name="106" href="#106">106</a> <em class="comment">/*<em class="comment"> Skip chars outside the lookup table */</em></em><a name="107" href="#107">107</a> <strong>if</strong> (lookup < 0 || lookup >= base32Lookup.length) {<a name="108" href="#108">108</a> <strong>continue</strong>;<a name="109" href="#109">109</a> }<a name="110" href="#110">110</a> <a name="111" href="#111">111</a> digit = base32Lookup[lookup];<a name="112" href="#112">112</a> <a name="113" href="#113">113</a> <em class="comment">/*<em class="comment"> If this digit is not in the table, ignore it */</em></em><a name="114" href="#114">114</a> <strong>if</strong> (digit == 0xFF) {<a name="115" href="#115">115</a> <strong>continue</strong>;<a name="116" href="#116">116</a> }<a name="117" href="#117">117</a> <a name="118" href="#118">118</a> <strong>if</strong> (index <= 3) {<a name="119" href="#119">119</a> index = (index + 5) % 8;<a name="120" href="#120">120</a> <strong>if</strong> (index == 0) {<a name="121" href="#121">121</a> bytes[offset] |= digit;<a name="122" href="#122">122</a> offset++;<a name="123" href="#123">123</a> <strong>if</strong> (offset >= bytes.length)<a name="124" href="#124">124</a> <strong>break</strong>;<a name="125" href="#125">125</a> } <strong>else</strong> {<a name="126" href="#126">126</a> bytes[offset] |= digit << (8 - index);<a name="127" href="#127">127</a> }<a name="128" href="#128">128</a> } <strong>else</strong> {<a name="129" href="#129">129</a> index = (index + 5) % 8;<a name="130" href="#130">130</a> bytes[offset] |= (digit >>> index);<a name="131" href="#131">131</a> offset++;<a name="132" href="#132">132</a> <a name="133" href="#133">133</a> <strong>if</strong> (offset >= bytes.length) {<a name="134" href="#134">134</a> <strong>break</strong>;<a name="135" href="#135">135</a> }<a name="136" href="#136">136</a> bytes[offset] |= digit << (8 - index);<a name="137" href="#137">137</a> }<a name="138" href="#138">138</a> }<a name="139" href="#139">139</a> <strong>return</strong> bytes;<a name="140" href="#140">140</a> }<a name="141" href="#141">141</a> <a name="142" href="#142">142</a> <em>/**<em>* For testing, take a command-line argument in Base32, decode, print in hex,</em></em><a name="143" href="#143">143</a> <em> * encode, print</em><a name="144" href="#144">144</a> <em> *</em><a name="145" href="#145">145</a> <em> * @param args</em><a name="146" href="#146">146</a> <em> */</em><a name="147" href="#147">147</a> <strong>static</strong> <strong>public</strong> <strong>void</strong> main(String[] args) {<a name="148" href="#148">148</a> <strong>if</strong> (args.length == 0) {<a name="149" href="#149">149</a> System.out.println(<span class="string">"Supply a Base32-encoded argument."</span>);<a name="150" href="#150">150</a> <strong>return</strong>;<a name="151" href="#151">151</a> }<a name="152" href="#152">152</a> System.out.println(<span class="string">" Original: "</span> + args[0]);<a name="153" href="#153">153</a> byte[] decoded = Base32.decode(args[0]);<a name="154" href="#154">154</a> System.out.print(<span class="string">" Hex: "</span>);<a name="155" href="#155">155</a> <strong>for</strong> (<strong>int</strong> i = 0; i < decoded.length; i++) {<a name="156" href="#156">156</a> <strong>int</strong> b = decoded[i];<a name="157" href="#157">157</a> <strong>if</strong> (b < 0) {<a name="158" href="#158">158</a> b += 256;<a name="159" href="#159">159</a> }<a name="160" href="#160">160</a> System.out.print((Integer.toHexString(b + 256)).substring(1));<a name="161" href="#161">161</a> }<a name="162" href="#162">162</a> System.out.println();<a name="163" href="#163">163</a> System.out.println(<span class="string">"Reencoded: "</span> + Base32.encode(decoded));<a name="164" href="#164">164</a> }<a name="165" href="#165">165</a> }</pre><hr/><div id="footer">This page was automatically generated by <a href="http://maven.apache.org/">Maven</a></div></body></html>?? 快捷鍵說明
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