bufferedseekinputstream.html

来自「网络爬虫开源代码」· HTML 代码 · 共 235 行 · 第 1/2 页

<a name="110" href="#110">110</a> 
<a name="111" href="#111">111</a>     <em>/**<em>*</em></em>
<a name="112" href="#112">112</a> <em>     * Returns the number of unread bytes in the current buffer.</em>
<a name="113" href="#113">113</a> <em>     * </em>
<a name="114" href="#114">114</a> <em>     * @return  the remaining bytes</em>
<a name="115" href="#115">115</a> <em>     */</em>
<a name="116" href="#116">116</a>     <strong>private</strong> <strong>int</strong> remaining() {
<a name="117" href="#117">117</a>         <strong>return</strong> maxOffset - offset;
<a name="118" href="#118">118</a>     }
<a name="119" href="#119">119</a> 
<a name="120" href="#120">120</a> 
<a name="121" href="#121">121</a>     @Override
<a name="122" href="#122">122</a>     <strong>public</strong> <strong>int</strong> read() throws IOException {
<a name="123" href="#123">123</a>         ensureBuffer();
<a name="124" href="#124">124</a>         <strong>if</strong> (maxOffset == 0) {
<a name="125" href="#125">125</a>             <strong>return</strong> -1;
<a name="126" href="#126">126</a>         }
<a name="127" href="#127">127</a>         <strong>int</strong> ch = buffer[offset] &amp; 0xFF;
<a name="128" href="#128">128</a>         offset++;
<a name="129" href="#129">129</a>         <strong>return</strong> ch;
<a name="130" href="#130">130</a>     }
<a name="131" href="#131">131</a> 
<a name="132" href="#132">132</a> 
<a name="133" href="#133">133</a>     @Override
<a name="134" href="#134">134</a>     <strong>public</strong> <strong>int</strong> read(byte[] buf, <strong>int</strong> ofs, <strong>int</strong> len) throws IOException {
<a name="135" href="#135">135</a>         ensureBuffer();
<a name="136" href="#136">136</a>         <strong>if</strong> (maxOffset == 0) {
<a name="137" href="#137">137</a>             <strong>return</strong> 0;
<a name="138" href="#138">138</a>         }
<a name="139" href="#139">139</a>         len = Math.min(len, remaining());
<a name="140" href="#140">140</a>         System.arraycopy(buffer, offset, buf, ofs, len);
<a name="141" href="#141">141</a>         offset += len;
<a name="142" href="#142">142</a>         <strong>return</strong> len;
<a name="143" href="#143">143</a>     }
<a name="144" href="#144">144</a> 
<a name="145" href="#145">145</a> 
<a name="146" href="#146">146</a>     @Override
<a name="147" href="#147">147</a>     <strong>public</strong> <strong>int</strong> read(byte[] buf) throws IOException {
<a name="148" href="#148">148</a>         <strong>return</strong> read(buf, 0, buf.length);
<a name="149" href="#149">149</a>     }
<a name="150" href="#150">150</a> 
<a name="151" href="#151">151</a> 
<a name="152" href="#152">152</a>     @Override
<a name="153" href="#153">153</a>     <strong>public</strong> <strong>long</strong> skip(<strong>long</strong> c) throws IOException {
<a name="154" href="#154">154</a>         ensureBuffer();
<a name="155" href="#155">155</a>         <strong>if</strong> (maxOffset == 0) {
<a name="156" href="#156">156</a>             <strong>return</strong> 0;
<a name="157" href="#157">157</a>         }
<a name="158" href="#158">158</a>         <strong>int</strong> count = (c > Integer.MAX_VALUE) ? Integer.MAX_VALUE : (<strong>int</strong>)c;
<a name="159" href="#159">159</a>         <strong>int</strong> skip = Math.min(count, remaining());
<a name="160" href="#160">160</a>         offset += skip;
<a name="161" href="#161">161</a>         <strong>return</strong> skip;
<a name="162" href="#162">162</a>     }
<a name="163" href="#163">163</a> 
<a name="164" href="#164">164</a> 
<a name="165" href="#165">165</a>     <em>/**<em>*</em></em>
<a name="166" href="#166">166</a> <em>     * Returns the stream's current position.</em>
<a name="167" href="#167">167</a> <em>     * </em>
<a name="168" href="#168">168</a> <em>     * @return  the current position</em>
<a name="169" href="#169">169</a> <em>     */</em>
<a name="170" href="#170">170</a>     <strong>public</strong> <strong>long</strong> position() throws IOException {
<a name="171" href="#171">171</a>         <strong>return</strong> input.position() - buffer.length + offset;
<a name="172" href="#172">172</a>     }
<a name="173" href="#173">173</a> 
<a name="174" href="#174">174</a> 
<a name="175" href="#175">175</a>     <em>/**<em>*</em></em>
<a name="176" href="#176">176</a> <em>     * Seeks to the given position.  This method avoids re-filling the buffer</em>
<a name="177" href="#177">177</a> <em>     * if at all possible.</em>
<a name="178" href="#178">178</a> <em>     * </em>
<a name="179" href="#179">179</a> <em>     * @param p  the position to set</em>
<a name="180" href="#180">180</a> <em>     * @throws IOException if an IO error occurs</em>
<a name="181" href="#181">181</a> <em>     */</em>
<a name="182" href="#182">182</a>     <strong>public</strong> <strong>void</strong> position(<strong>long</strong> p) throws IOException {
<a name="183" href="#183">183</a>         <strong>long</strong> blockStart = (input.position() - maxOffset) 
<a name="184" href="#184">184</a>          / buffer.length * buffer.length;
<a name="185" href="#185">185</a>         <strong>long</strong> blockEnd = blockStart + maxOffset;
<a name="186" href="#186">186</a>         <strong>if</strong> ((p >= blockStart) &amp;&amp; (p &lt; blockEnd)) {
<a name="187" href="#187">187</a>             <em class="comment">// Desired position is somewhere inside current buffer</em>
<a name="188" href="#188">188</a>             <strong>long</strong> adj = p - blockStart;
<a name="189" href="#189">189</a>             offset = (<strong>int</strong>)adj;
<a name="190" href="#190">190</a>             <strong>return</strong>;
<a name="191" href="#191">191</a>         }
<a name="192" href="#192">192</a>         positionDirect(p);
<a name="193" href="#193">193</a>     }
<a name="194" href="#194">194</a> 
<a name="195" href="#195">195</a> 
<a name="196" href="#196">196</a>     <em>/**<em>*</em></em>
<a name="197" href="#197">197</a> <em>     * Positions the underlying stream at the given position, then refills</em>
<a name="198" href="#198">198</a> <em>     * the buffer.</em>
<a name="199" href="#199">199</a> <em>     * </em>
<a name="200" href="#200">200</a> <em>     * @param p  the position to set</em>
<a name="201" href="#201">201</a> <em>     * @throws IOException  if an IO error occurs</em>
<a name="202" href="#202">202</a> <em>     */</em>
<a name="203" href="#203">203</a>     <strong>private</strong> <strong>void</strong> positionDirect(<strong>long</strong> p) throws IOException {
<a name="204" href="#204">204</a>         <strong>long</strong> newBlockStart = p / buffer.length * buffer.length;
<a name="205" href="#205">205</a>         input.position(newBlockStart);
<a name="206" href="#206">206</a>         buffer();
<a name="207" href="#207">207</a>         offset = (<strong>int</strong>)(p % buffer.length);        
<a name="208" href="#208">208</a>     }
<a name="209" href="#209">209</a> 
<a name="210" href="#210">210</a>     <em>/**<em>* </em></em>
<a name="211" href="#211">211</a> <em>     * Close the stream, including the wrapped input stream. </em>
<a name="212" href="#212">212</a> <em>     */</em>
<a name="213" href="#213">213</a>     <strong>public</strong> <strong>void</strong> close() throws IOException {
<a name="214" href="#214">214</a>         <strong>super</strong>.close();
<a name="215" href="#215">215</a>         <strong>if</strong>(<strong>this</strong>.input!=<strong>null</strong>) {
<a name="216" href="#216">216</a>             <strong>this</strong>.input.close();
<a name="217" href="#217">217</a>         }
<a name="218" href="#218">218</a>     }
<a name="219" href="#219">219</a> 
<a name="220" href="#220">220</a> 
<a name="221" href="#221">221</a> }
</pre>
<hr/><div id="footer">This page was automatically generated by <a href="http://maven.apache.org/">Maven</a></div></body>
</html>