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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>IoBuffer xref</title><link type="text/css" rel="stylesheet" href="../../../../stylesheet.css" /></head><body><div id="overview"><a href="../../../../../apidocs/org/apache/mina/common/IoBuffer.html">View Javadoc</a></div><pre><a name="1" href="#1">1</a> <em class="jxr_comment">/*</em><a name="2" href="#2">2</a> <em class="jxr_comment"> * Licensed to the Apache Software Foundation (ASF) under one</em><a name="3" href="#3">3</a> <em class="jxr_comment"> * or more contributor license agreements. See the NOTICE file</em><a name="4" href="#4">4</a> <em class="jxr_comment"> * distributed with this work for additional information</em><a name="5" href="#5">5</a> <em class="jxr_comment"> * regarding copyright ownership. The ASF licenses this file</em><a name="6" href="#6">6</a> <em class="jxr_comment"> * to you under the Apache License, Version 2.0 (the</em><a name="7" href="#7">7</a> <em class="jxr_comment"> * "License"); you may not use this file except in compliance</em><a name="8" href="#8">8</a> <em class="jxr_comment"> * with the License. You may obtain a copy of the License at</em><a name="9" href="#9">9</a> <em class="jxr_comment"> *</em><a name="10" href="#10">10</a> <em class="jxr_comment"> * <a href="http://www.apache.org/licenses/LICENSE-2.0" target="alexandria_uri">http://www.apache.org/licenses/LICENSE-2.0</a></em><a name="11" href="#11">11</a> <em class="jxr_comment"> *</em><a name="12" href="#12">12</a> <em class="jxr_comment"> * Unless required by applicable law or agreed to in writing,</em><a name="13" href="#13">13</a> <em class="jxr_comment"> * software distributed under the License is distributed on an</em><a name="14" href="#14">14</a> <em class="jxr_comment"> * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY</em><a name="15" href="#15">15</a> <em class="jxr_comment"> * KIND, either express or implied. See the License for the</em><a name="16" href="#16">16</a> <em class="jxr_comment"> * specific language governing permissions and limitations</em><a name="17" href="#17">17</a> <em class="jxr_comment"> * under the License.</em><a name="18" href="#18">18</a> <em class="jxr_comment"> *</em><a name="19" href="#19">19</a> <em class="jxr_comment"> */</em><a name="20" href="#20">20</a> <strong class="jxr_keyword">package</strong> org.apache.mina.common;<a name="21" href="#21">21</a> <a name="22" href="#22">22</a> <strong class="jxr_keyword">import</strong> java.io.IOException;<a name="23" href="#23">23</a> <strong class="jxr_keyword">import</strong> java.io.InputStream;<a name="24" href="#24">24</a> <strong class="jxr_keyword">import</strong> java.io.OutputStream;<a name="25" href="#25">25</a> <strong class="jxr_keyword">import</strong> java.nio.BufferOverflowException;<a name="26" href="#26">26</a> <strong class="jxr_keyword">import</strong> java.nio.ByteBuffer;<a name="27" href="#27">27</a> <strong class="jxr_keyword">import</strong> java.nio.ByteOrder;<a name="28" href="#28">28</a> <strong class="jxr_keyword">import</strong> java.nio.CharBuffer;<a name="29" href="#29">29</a> <strong class="jxr_keyword">import</strong> java.nio.DoubleBuffer;<a name="30" href="#30">30</a> <strong class="jxr_keyword">import</strong> java.nio.FloatBuffer;<a name="31" href="#31">31</a> <strong class="jxr_keyword">import</strong> java.nio.IntBuffer;<a name="32" href="#32">32</a> <strong class="jxr_keyword">import</strong> java.nio.LongBuffer;<a name="33" href="#33">33</a> <strong class="jxr_keyword">import</strong> java.nio.ReadOnlyBufferException;<a name="34" href="#34">34</a> <strong class="jxr_keyword">import</strong> java.nio.ShortBuffer;<a name="35" href="#35">35</a> <strong class="jxr_keyword">import</strong> java.nio.charset.CharacterCodingException;<a name="36" href="#36">36</a> <strong class="jxr_keyword">import</strong> java.nio.charset.CharsetDecoder;<a name="37" href="#37">37</a> <strong class="jxr_keyword">import</strong> java.nio.charset.CharsetEncoder;<a name="38" href="#38">38</a> <strong class="jxr_keyword">import</strong> java.util.EnumSet;<a name="39" href="#39">39</a> <strong class="jxr_keyword">import</strong> java.util.HashSet;<a name="40" href="#40">40</a> <strong class="jxr_keyword">import</strong> java.util.Set;<a name="41" href="#41">41</a> <a name="42" href="#42">42</a> <em class="jxr_javadoccomment">/**</em><a name="43" href="#43">43</a> <em class="jxr_javadoccomment"> * A byte buffer used by MINA applications.</em><a name="44" href="#44">44</a> <em class="jxr_javadoccomment"> * <p></em><a name="45" href="#45">45</a> <em class="jxr_javadoccomment"> * This is a replacement for {@link ByteBuffer}. Please refer to</em><a name="46" href="#46">46</a> <em class="jxr_javadoccomment"> * {@link ByteBuffer} documentation for preliminary usage. MINA does</em><a name="47" href="#47">47</a> <em class="jxr_javadoccomment"> * not use NIO {@link ByteBuffer} directly for two reasons:</em><a name="48" href="#48">48</a> <em class="jxr_javadoccomment"> * <ul></em><a name="49" href="#49">49</a> <em class="jxr_javadoccomment"> * <li>It doesn't provide useful getters and putters such as</em><a name="50" href="#50">50</a> <em class="jxr_javadoccomment"> * <code>fill</code>, <code>get/putString</code>, and</em><a name="51" href="#51">51</a> <em class="jxr_javadoccomment"> * <code>get/putAsciiInt()</code> enough.</li></em><a name="52" href="#52">52</a> <em class="jxr_javadoccomment"> * <li>It is difficult to write variable-length data due to its fixed</em><a name="53" href="#53">53</a> <em class="jxr_javadoccomment"> * capacity</li></em><a name="54" href="#54">54</a> <em class="jxr_javadoccomment"> * </ul></em><a name="55" href="#55">55</a> <em class="jxr_javadoccomment"> * </p></em><a name="56" href="#56">56</a> <em class="jxr_javadoccomment"> *</em><a name="57" href="#57">57</a> <em class="jxr_javadoccomment"> * <h2>Allocation</h2></em><a name="58" href="#58">58</a> <em class="jxr_javadoccomment"> * <p></em><a name="59" href="#59">59</a> <em class="jxr_javadoccomment"> * You can allocate a new heap buffer.</em><a name="60" href="#60">60</a> <em class="jxr_javadoccomment"> * <pre></em><a name="61" href="#61">61</a> <em class="jxr_javadoccomment"> * IoBuffer buf = IoBuffer.allocate(1024, false);</em><a name="62" href="#62">62</a> <em class="jxr_javadoccomment"> * </pre></em><a name="63" href="#63">63</a> <em class="jxr_javadoccomment"> * you can also allocate a new direct buffer:</em><a name="64" href="#64">64</a> <em class="jxr_javadoccomment"> * <pre></em><a name="65" href="#65">65</a> <em class="jxr_javadoccomment"> * IoBuffer buf = IoBuffer.allocate(1024, true);</em><a name="66" href="#66">66</a> <em class="jxr_javadoccomment"> * </pre></em><a name="67" href="#67">67</a> <em class="jxr_javadoccomment"> * or you can set the default buffer type.</em><a name="68" href="#68">68</a> <em class="jxr_javadoccomment"> * <pre></em><a name="69" href="#69">69</a> <em class="jxr_javadoccomment"> * // Allocate heap buffer by default.</em><a name="70" href="#70">70</a> <em class="jxr_javadoccomment"> * IoBuffer.setUseDirectBuffer(false);</em><a name="71" href="#71">71</a> <em class="jxr_javadoccomment"> * // A new heap buffer is returned.</em><a name="72" href="#72">72</a> <em class="jxr_javadoccomment"> * IoBuffer buf = IoBuffer.allocate(1024);</em><a name="73" href="#73">73</a> <em class="jxr_javadoccomment"> * </pre></em><a name="74" href="#74">74</a> <em class="jxr_javadoccomment"> * </p></em><a name="75" href="#75">75</a> <em class="jxr_javadoccomment"> *</em><a name="76" href="#76">76</a> <em class="jxr_javadoccomment"> * <h2>Wrapping existing NIO buffers and arrays</h2></em><a name="77" href="#77">77</a> <em class="jxr_javadoccomment"> * <p></em><a name="78" href="#78">78</a> <em class="jxr_javadoccomment"> * This class provides a few <tt>wrap(...)</tt> methods that wraps</em><a name="79" href="#79">79</a> <em class="jxr_javadoccomment"> * any NIO buffers and byte arrays.</em><a name="80" href="#80">80</a> <em class="jxr_javadoccomment"> *</em><a name="81" href="#81">81</a> <em class="jxr_javadoccomment"> * <h2>AutoExpand</h2></em><a name="82" href="#82">82</a> <em class="jxr_javadoccomment"> * <p></em><a name="83" href="#83">83</a> <em class="jxr_javadoccomment"> * Writing variable-length data using NIO <tt>ByteBuffers</tt> is not really</em><a name="84" href="#84">84</a> <em class="jxr_javadoccomment"> * easy, and it is because its size is fixed. {@link IoBuffer} introduces </em><a name="85" href="#85">85</a> <em class="jxr_javadoccomment"> * <tt>autoExpand</tt> property. If <tt>autoExpand</tt> property is true, you</em><a name="86" href="#86">86</a> <em class="jxr_javadoccomment"> * never get {@link BufferOverflowException} or</em><a name="87" href="#87">87</a> <em class="jxr_javadoccomment"> * {@link IndexOutOfBoundsException} (except when index is negative).</em><a name="88" href="#88">88</a> <em class="jxr_javadoccomment"> * It automatically expands its capacity and limit value. For example:</em><a name="89" href="#89">89</a> <em class="jxr_javadoccomment"> * <pre></em><a name="90" href="#90">90</a> <em class="jxr_javadoccomment"> * String greeting = messageBundle.getMessage( "hello" );</em><a name="91" href="#91">91</a> <em class="jxr_javadoccomment"> * IoBuffer buf = IoBuffer.allocate( 16 );</em><a name="92" href="#92">92</a> <em class="jxr_javadoccomment"> * // Turn on autoExpand (it is off by default)</em><a name="93" href="#93">93</a> <em class="jxr_javadoccomment"> * buf.setAutoExpand( true );</em><a name="94" href="#94">94</a> <em class="jxr_javadoccomment"> * buf.putString( greeting, utf8encoder );</em><a name="95" href="#95">95</a> <em class="jxr_javadoccomment"> * </pre></em><a name="96" href="#96">96</a> <em class="jxr_javadoccomment"> * The underlying {@link ByteBuffer} is reallocated by {@link IoBuffer} behind</em><a name="97" href="#97">97</a> <em class="jxr_javadoccomment"> * the scene if the encoded data is larger than 16 bytes in the example above.</em><a name="98" href="#98">98</a> <em class="jxr_javadoccomment"> * Its capacity will double, and its limit will increase to the last position</em><a name="99" href="#99">99</a> <em class="jxr_javadoccomment"> * the string is written.</em><a name="100" href="#100">100</a> <em class="jxr_javadoccomment"> * </p></em><a name="101" href="#101">101</a> <em class="jxr_javadoccomment"> * </em><a name="102" href="#102">102</a> <em class="jxr_javadoccomment"> * <h2>AutoShrink</h2></em><a name="103" href="#103">103</a> <em class="jxr_javadoccomment"> * <p></em><a name="104" href="#104">104</a> <em class="jxr_javadoccomment"> * You might also want to decrease the capacity of the buffer when most</em><a name="105" href="#105">105</a> <em class="jxr_javadoccomment"> * of the allocated memory area is not being used. {@link IoBuffer} provides</em><a name="106" href="#106">106</a> <em class="jxr_javadoccomment"> * <tt>autoShrink</tt> property to take care of this issue. If </em><a name="107" href="#107">107</a> <em class="jxr_javadoccomment"> * <tt>autoShrink</tt> is turned on, {@link IoBuffer} halves the capacity</em><a name="108" href="#108">108</a> <em class="jxr_javadoccomment"> * of the buffer when {@link #compact()} is invoked and only 1/4 or less of</em><a name="109" href="#109">109</a> <em class="jxr_javadoccomment"> * the current capacity is being used.</em><a name="110" href="#110">110</a> <em class="jxr_javadoccomment"> * <p></em><a name="111" href="#111">111</a> <em class="jxr_javadoccomment"> * You can also {@link #shrink()} method manually to shrink the capacity of</em><a name="112" href="#112">112</a> <em class="jxr_javadoccomment"> * the buffer.</em><a name="113" href="#113">113</a> <em class="jxr_javadoccomment"> * <p> </em>⌨️ 快捷键说明
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