gzippedinputstream.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="127" href="#127">127</a>         }
<a name="128" href="#128">128</a>         <strong>if</strong> (!<strong>this</strong>.inf.finished()) {
<a name="129" href="#129">129</a>             <strong>int</strong> read = 0;
<a name="130" href="#130">130</a>             <strong>while</strong> ((read = read()) != -1) {
<a name="131" href="#131">131</a>                 <strong>if</strong> ((byte)read == (byte)ignore) {
<a name="132" href="#132">132</a>                     <strong>continue</strong>;
<a name="133" href="#133">133</a>                 }
<a name="134" href="#134">134</a>                 bytesSkipped = gotoEOR() + 1;
<a name="135" href="#135">135</a>                 <strong>break</strong>;
<a name="136" href="#136">136</a>             }
<a name="137" href="#137">137</a>         }
<a name="138" href="#138">138</a>         <strong>return</strong> bytesSkipped;
<a name="139" href="#139">139</a>     }
<a name="140" href="#140">140</a>     
<a name="141" href="#141">141</a>     <em>/**<em>*</em></em>
<a name="142" href="#142">142</a> <em>     * Exhaust current GZIP member content.</em>
<a name="143" href="#143">143</a> <em>     * Call this method when you think you're on the end of the</em>
<a name="144" href="#144">144</a> <em>     * GZIP member.  It will clean out any dross.</em>
<a name="145" href="#145">145</a> <em>     * @return Count of characters skipped over.</em>
<a name="146" href="#146">146</a> <em>     * @throws IOException</em>
<a name="147" href="#147">147</a> <em>     */</em>
<a name="148" href="#148">148</a>     <strong>public</strong> <strong>long</strong> gotoEOR() throws IOException {
<a name="149" href="#149">149</a>         <strong>long</strong> bytesSkipped = 0;
<a name="150" href="#150">150</a>         <strong>if</strong> (<strong>this</strong>.inf.getTotalIn() &lt;= 0) {
<a name="151" href="#151">151</a>             <strong>return</strong> bytesSkipped;
<a name="152" href="#152">152</a>         }
<a name="153" href="#153">153</a>         <strong>while</strong>(!<strong>this</strong>.inf.finished()) {
<a name="154" href="#154">154</a>             bytesSkipped += skip(Long.MAX_VALUE);
<a name="155" href="#155">155</a>         }
<a name="156" href="#156">156</a>         <strong>return</strong> bytesSkipped;
<a name="157" href="#157">157</a>     }
<a name="158" href="#158">158</a>     
<a name="159" href="#159">159</a>     <em>/**<em>*</em></em>
<a name="160" href="#160">160</a> <em>     * Returns a GZIP Member Iterator.</em>
<a name="161" href="#161">161</a> <em>     * Has limitations. Can only get one Iterator per instance of this class;</em>
<a name="162" href="#162">162</a> <em>     * you must get new instance if you want to get Iterator again.</em>
<a name="163" href="#163">163</a> <em>     * @return Iterator over GZIP Members.</em>
<a name="164" href="#164">164</a> <em>     */</em>
<a name="165" href="#165">165</a>     <strong>public</strong> Iterator iterator() {
<a name="166" href="#166">166</a>         <strong>try</strong> {
<a name="167" href="#167">167</a>             <em class="comment">// We called mark in the constructor (See checkStream method).</em>
<a name="168" href="#168">168</a>             <strong>this</strong>.in.reset();
<a name="169" href="#169">169</a>         } <strong>catch</strong> (IOException e) {
<a name="170" href="#170">170</a>             <strong>throw</strong> <strong>new</strong> RuntimeException(e);
<a name="171" href="#171">171</a>         }
<a name="172" href="#172">172</a>         <strong>return</strong> <strong>new</strong> Iterator() {
<a name="173" href="#173">173</a>             <strong>private</strong> <a href="../../../org/archive/io/GzippedInputStream.html">GzippedInputStream</a> compressedStream =
<a name="174" href="#174">174</a>                 GzippedInputStream.<strong>this</strong>;
<a name="175" href="#175">175</a>             
<a name="176" href="#176">176</a>             <strong>public</strong> <strong>boolean</strong> hasNext() {
<a name="177" href="#177">177</a>                 <strong>try</strong> {
<a name="178" href="#178">178</a>                     gotoEOR();
<a name="179" href="#179">179</a>                 } <strong>catch</strong> (IOException e) {
<a name="180" href="#180">180</a>                     <strong>throw</strong> <strong>new</strong> RuntimeException(e);
<a name="181" href="#181">181</a>                 }
<a name="182" href="#182">182</a>                 <strong>return</strong> moveToNextGzipMember();
<a name="183" href="#183">183</a>             }
<a name="184" href="#184">184</a>             
<a name="185" href="#185">185</a>             <em>/**<em>*</em></em>
<a name="186" href="#186">186</a> <em>             * @return An InputStream onto a GZIP Member.</em>
<a name="187" href="#187">187</a> <em>             */</em>
<a name="188" href="#188">188</a>             <strong>public</strong> Object next() {
<a name="189" href="#189">189</a>                 <strong>try</strong> {
<a name="190" href="#190">190</a>                     gzipMemberSeek();
<a name="191" href="#191">191</a>                 } <strong>catch</strong> (IOException e) {
<a name="192" href="#192">192</a>                     <strong>throw</strong> <strong>new</strong> RuntimeException(<span class="string">"Failed move to EOR or "</span> +
<a name="193" href="#193">193</a>                         <span class="string">"failed header read: "</span> + e.getMessage());
<a name="194" href="#194">194</a>                 }
<a name="195" href="#195">195</a>                 <strong>return</strong> <strong>this</strong>.compressedStream;
<a name="196" href="#196">196</a>             }
<a name="197" href="#197">197</a>             
<a name="198" href="#198">198</a>             <strong>public</strong> <strong>void</strong> remove() {
<a name="199" href="#199">199</a>                 <strong>throw</strong> <strong>new</strong> UnsupportedOperationException();
<a name="200" href="#200">200</a>             }
<a name="201" href="#201">201</a>         };   
<a name="202" href="#202">202</a>     }
<a name="203" href="#203">203</a>     
<a name="204" href="#204">204</a>     <em>/**<em>*</em></em>
<a name="205" href="#205">205</a> <em>     * @return True if we found another record in the stream.</em>
<a name="206" href="#206">206</a> <em>     */</em>
<a name="207" href="#207">207</a>     <strong>protected</strong> <strong>boolean</strong> moveToNextGzipMember() {
<a name="208" href="#208">208</a>         <strong>boolean</strong> result = false;
<a name="209" href="#209">209</a>         <em class="comment">// Move to the next gzip member, if there is one, positioning</em>
<a name="210" href="#210">210</a>         <em class="comment">// ourselves by backing up the stream so we reread any inflater</em>
<a name="211" href="#211">211</a>         <em class="comment">// remaining bytes. Then add 8 bytes to get us past the GZIP</em>
<a name="212" href="#212">212</a>         <em class="comment">// CRC trailer block that ends all gzip members.</em>
<a name="213" href="#213">213</a>         <strong>try</strong> {
<a name="214" href="#214">214</a>             RepositionableStream ps =
<a name="215" href="#215">215</a>                 (RepositionableStream)getInputStream();
<a name="216" href="#216">216</a>             <em class="comment">// 8 is sizeof gzip CRC block thats on tail of gzipped</em>
<a name="217" href="#217">217</a>             <em class="comment">// record. If remaining is &lt; 8 then experience indicates</em>
<a name="218" href="#218">218</a>             <em class="comment">// we're seeking past the gzip header -- don't backup the</em>
<a name="219" href="#219">219</a>             <em class="comment">// stream.</em>
<a name="220" href="#220">220</a>             <strong>if</strong> (getInflater().getRemaining() > GZIP_TRAILER_LENGTH) {
<a name="221" href="#221">221</a>                 ps.position(position() - getInflater().getRemaining() +
<a name="222" href="#222">222</a>                     GZIP_TRAILER_LENGTH);
<a name="223" href="#223">223</a>             }
<a name="224" href="#224">224</a>             <em class="comment">// If at least MINIMAL_GZIP_HEADER_LENGTH available assume</em>
<a name="225" href="#225">225</a>             <em class="comment">// possible other gzip member. Move the stream on checking</em>
<a name="226" href="#226">226</a>             <em class="comment">// as we go to be sure of another record. We do this slow</em>
<a name="227" href="#227">227</a>             <em class="comment">// poke ahead because the calculation using</em>
<a name="228" href="#228">228</a>             <em class="comment">// this.inf.getRemaining can be off by a couple if the</em>
<a name="229" href="#229">229</a>             <em class="comment">// remaining is zero.  There seems to be nothing in</em>
<a name="230" href="#230">230</a>             <em class="comment">// gzipinputstream nor in the inflater that can be relied</em>
<a name="231" href="#231">231</a>             <em class="comment">// upon:  this.eos = false, this.inf.finished = false,</em>
<a name="232" href="#232">232</a>             <em class="comment">// this.inf.readEOF is true. I don't know why its messed up</em>
<a name="233" href="#233">233</a>             <em class="comment">// like this.  Study the core zlib and see if can figure</em>
<a name="234" href="#234">234</a>             <em class="comment">// where inflater is going wrong.</em>
<a name="235" href="#235">235</a>             <strong>int</strong> read = -1;
<a name="236" href="#236">236</a>             <strong>int</strong> headerRead = 0;
<a name="237" href="#237">237</a>             <strong>while</strong> (getInputStream().available() >
<a name="238" href="#238">238</a>                     GzipHeader.MINIMAL_GZIP_HEADER_LENGTH) {
<a name="239" href="#239">239</a>                 read = getGzipHeader().readByte(getInputStream());
<a name="240" href="#240">240</a>                 <strong>if</strong> ((byte)read == (byte)GZIPInputStream.GZIP_MAGIC) {
<a name="241" href="#241">241</a>                     headerRead++;
<a name="242" href="#242">242</a>                     read = getGzipHeader().readByte(getInputStream());
<a name="243" href="#243">243</a>                     <strong>if</strong>((byte)read ==
<a name="244" href="#244">244</a>                             (byte)(GZIPInputStream.GZIP_MAGIC >> 8)) {
<a name="245" href="#245">245</a>                         headerRead++;
<a name="246" href="#246">246</a>                         read =
<a name="247" href="#247">247</a>                             getGzipHeader().readByte(getInputStream());
<a name="248" href="#248">248</a>                         <strong>if</strong> ((byte)read == Deflater.DEFLATED) {
<a name="249" href="#249">249</a>                             headerRead++;
<a name="250" href="#250">250</a>                             <em class="comment">// Found gzip header. Backup the stream the</em>
<a name="251" href="#251">251</a>                             <em class="comment">// two bytes we just found and set result</em>
<a name="252" href="#252">252</a>                             <em class="comment">// true.</em>
<a name="253" href="#253">253</a>                             ps.position(position() - headerRead);
<a name="254" href="#254">254</a>                             result = <strong>true</strong>;
<a name="255" href="#255">255</a>                             <strong>break</strong>;
<a name="256" href="#256">256</a>                         }
<a name="257" href="#257">257</a>                     }
<a name="258" href="#258">258</a>                     <em class="comment">// Didn't find gzip header.  Back up stream one</em>
<a name="259" href="#259">259</a>                     <em class="comment">// byte because the byte just read might be the</em>
<a name="260" href="#260">260</a>                     <em class="comment">// actual start of the gzip header. Needs testing.</em>
<a name="261" href="#261">261</a>                     ps.position(position() - headerRead);