arcutils.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="121" href="#121">121</a>             throws IOException {
<a name="122" href="#122">122</a>         <strong>boolean</strong> compressedARCFile = false;
<a name="123" href="#123">123</a>         <a href="../../../../org/archive/io/GzipHeader.html">GzipHeader</a> gh = <strong>null</strong>;
<a name="124" href="#124">124</a>         <strong>try</strong> {
<a name="125" href="#125">125</a>             gh = <strong>new</strong> <a href="../../../../org/archive/io/GzipHeader.html">GzipHeader</a>(is);
<a name="126" href="#126">126</a>         } <strong>catch</strong> (NoGzipMagicException e ) {
<a name="127" href="#127">127</a>             <strong>return</strong> compressedARCFile;
<a name="128" href="#128">128</a>         }
<a name="129" href="#129">129</a>         
<a name="130" href="#130">130</a>         byte[] fextra = gh.getFextra();
<a name="131" href="#131">131</a>         <em class="comment">// Now make sure following bytes are IA GZIP comment.</em>
<a name="132" href="#132">132</a>         <em class="comment">// First check length. ARC_GZIP_EXTRA_FIELD includes length</em>
<a name="133" href="#133">133</a>         <em class="comment">// so subtract two and start compare to ARC_GZIP_EXTRA_FIELD</em>
<a name="134" href="#134">134</a>         <em class="comment">// at +2.</em>
<a name="135" href="#135">135</a>         <strong>if</strong> (fextra != <strong>null</strong> &amp;&amp;
<a name="136" href="#136">136</a>         		ARC_GZIP_EXTRA_FIELD.length - 2 == fextra.length) {
<a name="137" href="#137">137</a>             compressedARCFile = <strong>true</strong>;
<a name="138" href="#138">138</a>             <strong>for</strong> (<strong>int</strong> i = 0; i &lt; fextra.length; i++) {
<a name="139" href="#139">139</a>                 <strong>if</strong> (fextra[i] != ARC_GZIP_EXTRA_FIELD[i + 2]) {
<a name="140" href="#140">140</a>                     compressedARCFile = false;
<a name="141" href="#141">141</a>                     <strong>break</strong>;
<a name="142" href="#142">142</a>                 }
<a name="143" href="#143">143</a>             }
<a name="144" href="#144">144</a>         }
<a name="145" href="#145">145</a>         <strong>return</strong> compressedARCFile;
<a name="146" href="#146">146</a>     }
<a name="147" href="#147">147</a>     
<a name="148" href="#148">148</a>     <em>/**<em>*</em></em>
<a name="149" href="#149">149</a> <em>     * Tests passed stream is gzip stream by reading in the HEAD.</em>
<a name="150" href="#150">150</a> <em>     * Does reposition of stream when done.</em>
<a name="151" href="#151">151</a> <em>     * @param rs An InputStream that is Repositionable.</em>
<a name="152" href="#152">152</a> <em>     * @return True if compressed stream.</em>
<a name="153" href="#153">153</a> <em>     * @throws IOException</em>
<a name="154" href="#154">154</a> <em>     */</em>
<a name="155" href="#155">155</a>     <strong>public</strong> <strong>static</strong> <strong>boolean</strong> testCompressedRepositionalStream(
<a name="156" href="#156">156</a>             <strong>final</strong> RepositionableStream rs)
<a name="157" href="#157">157</a>     throws IOException {
<a name="158" href="#158">158</a>         <strong>boolean</strong> compressedARCFile = false;
<a name="159" href="#159">159</a>         <strong>long</strong> p = rs.position();
<a name="160" href="#160">160</a>         <strong>try</strong> {
<a name="161" href="#161">161</a>             compressedARCFile = testCompressedStream((InputStream)rs);
<a name="162" href="#162">162</a>         } <strong>finally</strong> {
<a name="163" href="#163">163</a>             rs.position(p);
<a name="164" href="#164">164</a>         }
<a name="165" href="#165">165</a>         <strong>return</strong> compressedARCFile; 
<a name="166" href="#166">166</a>     }
<a name="167" href="#167">167</a>     
<a name="168" href="#168">168</a>     <em>/**<em>*</em></em>
<a name="169" href="#169">169</a> <em>     * Tests passed stream is gzip stream by reading in the HEAD.</em>
<a name="170" href="#170">170</a> <em>     * Does reposition of stream when done.</em>
<a name="171" href="#171">171</a> <em>     * @param is An InputStream.</em>
<a name="172" href="#172">172</a> <em>     * @return True if compressed stream.</em>
<a name="173" href="#173">173</a> <em>     * @throws IOException</em>
<a name="174" href="#174">174</a> <em>     */</em>
<a name="175" href="#175">175</a>     <strong>public</strong> <strong>static</strong> <strong>boolean</strong> testCompressedStream(<strong>final</strong> InputStream is)
<a name="176" href="#176">176</a>     throws IOException {
<a name="177" href="#177">177</a>         <strong>boolean</strong> compressedARCFile = false;
<a name="178" href="#178">178</a>         <strong>try</strong> {
<a name="179" href="#179">179</a>             <strong>new</strong> <a href="../../../../org/archive/io/GzipHeader.html">GzipHeader</a>(is);
<a name="180" href="#180">180</a>             compressedARCFile = <strong>true</strong>;
<a name="181" href="#181">181</a>         } <strong>catch</strong> (NoGzipMagicException e) {
<a name="182" href="#182">182</a>             <strong>return</strong> compressedARCFile;
<a name="183" href="#183">183</a>         }
<a name="184" href="#184">184</a>         <strong>return</strong> compressedARCFile;
<a name="185" href="#185">185</a>     }
<a name="186" href="#186">186</a>     
<a name="187" href="#187">187</a>     <em>/**<em>*</em></em>
<a name="188" href="#188">188</a> <em>     * Check file is uncompressed ARC file.</em>
<a name="189" href="#189">189</a> <em>     * </em>
<a name="190" href="#190">190</a> <em>     * @param arcFile</em>
<a name="191" href="#191">191</a> <em>     *            File to test if its Internet Archive ARC file uncompressed.</em>
<a name="192" href="#192">192</a> <em>     * </em>
<a name="193" href="#193">193</a> <em>     * @return True if this is an Internet Archive ARC file.</em>
<a name="194" href="#194">194</a> <em>     * </em>
<a name="195" href="#195">195</a> <em>     * @exception IOException</em>
<a name="196" href="#196">196</a> <em>     *                If file does not exist or is not unreadable.</em>
<a name="197" href="#197">197</a> <em>     */</em>
<a name="198" href="#198">198</a>     <strong>public</strong> <strong>static</strong> <strong>boolean</strong> testUncompressedARCFile(File arcFile)
<a name="199" href="#199">199</a>     throws IOException {
<a name="200" href="#200">200</a>         <strong>boolean</strong> uncompressedARCFile = false;
<a name="201" href="#201">201</a>         isReadable(arcFile);
<a name="202" href="#202">202</a>         <strong>if</strong>(arcFile.getName().toLowerCase().endsWith(ARC_FILE_EXTENSION)) {
<a name="203" href="#203">203</a>             FileInputStream fis = <strong>new</strong> FileInputStream(arcFile);
<a name="204" href="#204">204</a>             <strong>try</strong> {
<a name="205" href="#205">205</a>                 byte [] b = <strong>new</strong> byte[ARC_MAGIC_NUMBER.length()];
<a name="206" href="#206">206</a>                 <strong>int</strong> read = fis.read(b, 0, ARC_MAGIC_NUMBER.length());
<a name="207" href="#207">207</a>                 fis.close();
<a name="208" href="#208">208</a>                 <strong>if</strong> (read == ARC_MAGIC_NUMBER.length()) {
<a name="209" href="#209">209</a>                     StringBuffer beginStr
<a name="210" href="#210">210</a>                         = <strong>new</strong> StringBuffer(ARC_MAGIC_NUMBER.length());
<a name="211" href="#211">211</a>                     <strong>for</strong> (<strong>int</strong> i = 0; i &lt; ARC_MAGIC_NUMBER.length(); i++) {
<a name="212" href="#212">212</a>                         beginStr.append((<strong>char</strong>)b[i]);
<a name="213" href="#213">213</a>                     }
<a name="214" href="#214">214</a>                     
<a name="215" href="#215">215</a>                     <strong>if</strong> (beginStr.toString().
<a name="216" href="#216">216</a>                             equalsIgnoreCase(ARC_MAGIC_NUMBER)) {
<a name="217" href="#217">217</a>                         uncompressedARCFile = <strong>true</strong>;
<a name="218" href="#218">218</a>                     }
<a name="219" href="#219">219</a>                 }
<a name="220" href="#220">220</a>             } <strong>finally</strong> {
<a name="221" href="#221">221</a>                 fis.close();
<a name="222" href="#222">222</a>             }
<a name="223" href="#223">223</a>         }
<a name="224" href="#224">224</a> 
<a name="225" href="#225">225</a>         <strong>return</strong> uncompressedARCFile;
<a name="226" href="#226">226</a>     }
<a name="227" href="#227">227</a>     
<a name="228" href="#228">228</a> 
<a name="229" href="#229">229</a>     <em>/**<em>*</em></em>
<a name="230" href="#230">230</a> <em>     * @param arcFile File to test.</em>
<a name="231" href="#231">231</a> <em>     * @exception IOException If file does not exist or is not unreadable.</em>
<a name="232" href="#232">232</a> <em>     */</em>
<a name="233" href="#233">233</a>     <strong>private</strong> <strong>static</strong> <strong>void</strong> isReadable(File arcFile) throws IOException {
<a name="234" href="#234">234</a>         <strong>if</strong> (!arcFile.exists()) {
<a name="235" href="#235">235</a>             <strong>throw</strong> <strong>new</strong> FileNotFoundException(arcFile.getAbsolutePath() +
<a name="236" href="#236">236</a>                 <span class="string">" does not exist."</span>);
<a name="237" href="#237">237</a>         }
<a name="238" href="#238">238</a> 
<a name="239" href="#239">239</a>         <strong>if</strong> (!arcFile.canRead()) {
<a name="240" href="#240">240</a>             <strong>throw</strong> <strong>new</strong> FileNotFoundException(arcFile.getAbsolutePath() +
<a name="241" href="#241">241</a>                 <span class="string">" is not readable."</span>);
<a name="242" href="#242">242</a>         }
<a name="243" href="#243">243</a>     }
<a name="244" href="#244">244</a> }
</pre>
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