randomaccessinputstream.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="93" href="#93">93</a>      <strong>public</strong> <a href="../../../org/archive/io/RandomAccessInputStream.html">RandomAccessInputStream</a>(<strong>final</strong> File file, <strong>final</strong> <strong>long</strong> offset)
<a name="94" href="#94">94</a>      throws IOException {
<a name="95" href="#95">95</a>          <strong>this</strong>(<strong>new</strong> RandomAccessFile(file, <span class="string">"r"</span>), <strong>true</strong>, offset);
<a name="96" href="#96">96</a>      }
<a name="97" href="#97">97</a>      
<a name="98" href="#98">98</a>      <em>/**<em>*</em></em>
<a name="99" href="#99">99</a>  <em>     * @param raf RandomAccessFile to wrap.</em>
<a name="100" href="#100">100</a> <em>     * @param sympathyClose Set to true if we are to close the RAF</em>
<a name="101" href="#101">101</a> <em>     * file when this stream is closed.</em>
<a name="102" href="#102">102</a> <em>     * @param offset </em>
<a name="103" href="#103">103</a> <em>     * @throws IOException</em>
<a name="104" href="#104">104</a> <em>     */</em>
<a name="105" href="#105">105</a>     <strong>public</strong> <a href="../../../org/archive/io/RandomAccessInputStream.html">RandomAccessInputStream</a>(<strong>final</strong> RandomAccessFile raf,
<a name="106" href="#106">106</a>             <strong>final</strong> <strong>boolean</strong> sympathyClose, <strong>final</strong> <strong>long</strong> offset)
<a name="107" href="#107">107</a>     throws IOException {
<a name="108" href="#108">108</a>         <strong>super</strong>();
<a name="109" href="#109">109</a>         <strong>this</strong>.sympathyClose = sympathyClose;
<a name="110" href="#110">110</a>         <strong>this</strong>.raf = raf;
<a name="111" href="#111">111</a>         <strong>if</strong> (offset > 0) {
<a name="112" href="#112">112</a>             <strong>this</strong>.raf.seek(offset);
<a name="113" href="#113">113</a>         }
<a name="114" href="#114">114</a>     }
<a name="115" href="#115">115</a> 
<a name="116" href="#116">116</a>     <em class="comment">/*<em class="comment"> (non-Javadoc)</em></em>
<a name="117" href="#117">117</a> <em class="comment">     * @see java.io.InputStream#read()</em>
<a name="118" href="#118">118</a> <em class="comment">     */</em>
<a name="119" href="#119">119</a>     <strong>public</strong> <strong>int</strong> read() throws IOException {
<a name="120" href="#120">120</a>         <strong>return</strong> <strong>this</strong>.raf.read();
<a name="121" href="#121">121</a>     }
<a name="122" href="#122">122</a> 
<a name="123" href="#123">123</a>     <em class="comment">/*<em class="comment"> (non-Javadoc)</em></em>
<a name="124" href="#124">124</a> <em class="comment">     * @see java.io.InputStream#read(byte[], int, int)</em>
<a name="125" href="#125">125</a> <em class="comment">     */</em>
<a name="126" href="#126">126</a>     <strong>public</strong> <strong>int</strong> read(byte[] b, <strong>int</strong> off, <strong>int</strong> len) throws IOException {
<a name="127" href="#127">127</a>         <strong>return</strong> <strong>this</strong>.raf.read(b, off, len);
<a name="128" href="#128">128</a>     }
<a name="129" href="#129">129</a>     
<a name="130" href="#130">130</a>     <em class="comment">/*<em class="comment"> (non-Javadoc)</em></em>
<a name="131" href="#131">131</a> <em class="comment">     * @see java.io.InputStream#read(byte[])</em>
<a name="132" href="#132">132</a> <em class="comment">     */</em>
<a name="133" href="#133">133</a>     <strong>public</strong> <strong>int</strong> read(byte[] b) throws IOException {
<a name="134" href="#134">134</a>         <strong>return</strong> <strong>this</strong>.raf.read(b);
<a name="135" href="#135">135</a>     }
<a name="136" href="#136">136</a> 
<a name="137" href="#137">137</a>     <em class="comment">/*<em class="comment"> (non-Javadoc)</em></em>
<a name="138" href="#138">138</a> <em class="comment">     * @see java.io.InputStream#skip(long)</em>
<a name="139" href="#139">139</a> <em class="comment">     */</em>
<a name="140" href="#140">140</a>     <strong>public</strong> <strong>long</strong> skip(<strong>long</strong> n) throws IOException {
<a name="141" href="#141">141</a>         <strong>this</strong>.raf.seek(<strong>this</strong>.raf.getFilePointer() + n);
<a name="142" href="#142">142</a>         <strong>return</strong> n;
<a name="143" href="#143">143</a>     }
<a name="144" href="#144">144</a> 
<a name="145" href="#145">145</a> 	<strong>public</strong> <strong>long</strong> position() throws IOException {
<a name="146" href="#146">146</a> 		<strong>return</strong> <strong>this</strong>.raf.getFilePointer();
<a name="147" href="#147">147</a> 	}
<a name="148" href="#148">148</a> 
<a name="149" href="#149">149</a> 	<strong>public</strong> <strong>void</strong> position(<strong>long</strong> position) throws IOException {
<a name="150" href="#150">150</a> 		<strong>this</strong>.raf.seek(position);
<a name="151" href="#151">151</a> 	}
<a name="152" href="#152">152</a>     
<a name="153" href="#153">153</a> 	<strong>public</strong> <strong>int</strong> available() throws IOException {
<a name="154" href="#154">154</a>         <strong>long</strong> amount = <strong>this</strong>.raf.length() - <strong>this</strong>.position();
<a name="155" href="#155">155</a>         <strong>return</strong> (amount >= Integer.MAX_VALUE)? Integer.MAX_VALUE: (<strong>int</strong>)amount;
<a name="156" href="#156">156</a> 	}
<a name="157" href="#157">157</a> 	
<a name="158" href="#158">158</a>     <strong>public</strong> <strong>boolean</strong> markSupported() {
<a name="159" href="#159">159</a>         <strong>return</strong> <strong>true</strong>;
<a name="160" href="#160">160</a>     }
<a name="161" href="#161">161</a>     
<a name="162" href="#162">162</a>     <strong>public</strong> <strong>synchronized</strong> <strong>void</strong> mark(<strong>int</strong> readlimit) {
<a name="163" href="#163">163</a>         <strong>try</strong> {
<a name="164" href="#164">164</a>             <strong>this</strong>.markpos = position();
<a name="165" href="#165">165</a>         } <strong>catch</strong> (IOException e) {
<a name="166" href="#166">166</a>             <em class="comment">// Set markpos to -1. Will cause exception reset.</em>
<a name="167" href="#167">167</a>             <strong>this</strong>.markpos = -1;
<a name="168" href="#168">168</a>         }
<a name="169" href="#169">169</a>     }
<a name="170" href="#170">170</a>     
<a name="171" href="#171">171</a>     <strong>public</strong> <strong>synchronized</strong> <strong>void</strong> reset() throws IOException {
<a name="172" href="#172">172</a>         <strong>if</strong> (<strong>this</strong>.markpos == -1) {
<a name="173" href="#173">173</a>             <strong>throw</strong> <strong>new</strong> IOException(<span class="string">"Mark has not been set."</span>);
<a name="174" href="#174">174</a>         }
<a name="175" href="#175">175</a>         position(<strong>this</strong>.markpos);
<a name="176" href="#176">176</a>     }
<a name="177" href="#177">177</a>     
<a name="178" href="#178">178</a>     <strong>public</strong> <strong>void</strong> close() throws IOException {
<a name="179" href="#179">179</a>         <strong>try</strong> {
<a name="180" href="#180">180</a>             <strong>super</strong>.close();
<a name="181" href="#181">181</a>         } <strong>finally</strong> {
<a name="182" href="#182">182</a>             <strong>if</strong> (<strong>this</strong>.sympathyClose) {
<a name="183" href="#183">183</a>                 <strong>this</strong>.raf.close();
<a name="184" href="#184">184</a>             }
<a name="185" href="#185">185</a>         }
<a name="186" href="#186">186</a>     }
<a name="187" href="#187">187</a> }
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