replaycharsequencefactory.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="288" href="#288">288</a> <em>         */</em>
<a name="289" href="#289">289</a>         <strong>private</strong> <strong>int</strong> wrapOrigin;
<a name="290" href="#290">290</a> 
<a name="291" href="#291">291</a>         <em>/**<em>*</em></em>
<a name="292" href="#292">292</a> <em>         * Index in wraparoundBuffer that corresponds to wrapOrigin</em>
<a name="293" href="#293">293</a> <em>         */</em>
<a name="294" href="#294">294</a>         <strong>private</strong> <strong>int</strong> wrapOffset;
<a name="295" href="#295">295</a> 
<a name="296" href="#296">296</a>         <em>/**<em>*</em></em>
<a name="297" href="#297">297</a> <em>         * Name of backing file we go to when we've exhausted content from the</em>
<a name="298" href="#298">298</a> <em>         * prefix buffer.</em>
<a name="299" href="#299">299</a> <em>         */</em>
<a name="300" href="#300">300</a>         <strong>private</strong> String backingFilename;
<a name="301" href="#301">301</a> 
<a name="302" href="#302">302</a>         <em>/**<em>*</em></em>
<a name="303" href="#303">303</a> <em>         * Random access to the backing file.</em>
<a name="304" href="#304">304</a> <em>         */</em>
<a name="305" href="#305">305</a>         <strong>private</strong> RandomAccessFile raFile;
<a name="306" href="#306">306</a> 
<a name="307" href="#307">307</a>         <em>/**<em>*</em></em>
<a name="308" href="#308">308</a> <em>         * Offset into prefix buffer at which content beings.</em>
<a name="309" href="#309">309</a> <em>         */</em>
<a name="310" href="#310">310</a>         <strong>private</strong> <strong>int</strong> contentOffset;
<a name="311" href="#311">311</a> 
<a name="312" href="#312">312</a>         <em>/**<em>*</em></em>
<a name="313" href="#313">313</a> <em>         * 8-bit encoding used reading single bytes from buffer and</em>
<a name="314" href="#314">314</a> <em>         * stream.</em>
<a name="315" href="#315">315</a> <em>         */</em>
<a name="316" href="#316">316</a>         <strong>private</strong> <strong>static</strong> <strong>final</strong> String DEFAULT_SINGLE_BYTE_ENCODING =
<a name="317" href="#317">317</a>             <span class="string">"ISO-8859-1"</span>;
<a name="318" href="#318">318</a> 
<a name="319" href="#319">319</a> 
<a name="320" href="#320">320</a>         <em>/**<em>*</em></em>
<a name="321" href="#321">321</a> <em>         * Constructor.</em>
<a name="322" href="#322">322</a> <em>         *</em>
<a name="323" href="#323">323</a> <em>         * @param buffer In-memory buffer of recordings prefix.  We read from</em>
<a name="324" href="#324">324</a> <em>         * here first and will only go to the backing file if &lt;code>size&lt;/code></em>
<a name="325" href="#325">325</a> <em>         * requested is greater than &lt;code>buffer.length&lt;/code>.</em>
<a name="326" href="#326">326</a> <em>         * @param size Total size of stream to replay in bytes.  Used to find</em>
<a name="327" href="#327">327</a> <em>         * EOS. This is total length of content including HTTP headers if</em>
<a name="328" href="#328">328</a> <em>         * present.</em>
<a name="329" href="#329">329</a> <em>         * @param responseBodyStart Where the response body starts in bytes.</em>
<a name="330" href="#330">330</a> <em>         * Used to skip over the HTTP headers if present.</em>
<a name="331" href="#331">331</a> <em>         * @param backingFilename Path to backing file with content in excess of</em>
<a name="332" href="#332">332</a> <em>         * whats in &lt;code>buffer&lt;/code>.</em>
<a name="333" href="#333">333</a> <em>         *</em>
<a name="334" href="#334">334</a> <em>         * @throws IOException</em>
<a name="335" href="#335">335</a> <em>         */</em>
<a name="336" href="#336">336</a>         <strong>private</strong> ByteReplayCharSequence(byte[] buffer, <strong>long</strong> size,
<a name="337" href="#337">337</a>                 <strong>long</strong> responseBodyStart, String backingFilename)
<a name="338" href="#338">338</a>             throws IOException {
<a name="339" href="#339">339</a> 
<a name="340" href="#340">340</a>             <strong>this</strong>.length = (<strong>int</strong>)(size - responseBodyStart);
<a name="341" href="#341">341</a>             <strong>this</strong>.absoluteLength = (<strong>int</strong>)size;
<a name="342" href="#342">342</a>             <strong>this</strong>.prefixBuffer = buffer;
<a name="343" href="#343">343</a>             <strong>this</strong>.contentOffset = (<strong>int</strong>)responseBodyStart;
<a name="344" href="#344">344</a> 
<a name="345" href="#345">345</a>             <em class="comment">// If amount to read is > than what is in our prefix buffer, then</em>
<a name="346" href="#346">346</a>             <em class="comment">// open the backing file.</em>
<a name="347" href="#347">347</a>             <strong>if</strong> (size > buffer.length) {
<a name="348" href="#348">348</a>                 <strong>this</strong>.backingFilename = backingFilename;
<a name="349" href="#349">349</a>                 <strong>this</strong>.raFile = <strong>new</strong> RandomAccessFile(backingFilename, <span class="string">"r"</span>);
<a name="350" href="#350">350</a>                 <strong>this</strong>.wraparoundBuffer = <strong>new</strong> byte[<strong>this</strong>.prefixBuffer.length];
<a name="351" href="#351">351</a>                 <strong>this</strong>.wrapOrigin = <strong>this</strong>.prefixBuffer.length;
<a name="352" href="#352">352</a>                 <strong>this</strong>.wrapOffset = 0;
<a name="353" href="#353">353</a>                 loadBuffer();
<a name="354" href="#354">354</a>             }
<a name="355" href="#355">355</a>         }
<a name="356" href="#356">356</a> 
<a name="357" href="#357">357</a>         <em>/**<em>*</em></em>
<a name="358" href="#358">358</a> <em>         * @return Length of characters in stream to replay.  Starts counting</em>
<a name="359" href="#359">359</a> <em>         * at the HTTP header/body boundary.</em>
<a name="360" href="#360">360</a> <em>         */</em>
<a name="361" href="#361">361</a>         <strong>public</strong> <strong>int</strong> length() {
<a name="362" href="#362">362</a>             <strong>return</strong> <strong>this</strong>.length;
<a name="363" href="#363">363</a>         }
<a name="364" href="#364">364</a> 
<a name="365" href="#365">365</a>         <em>/**<em>*</em></em>
<a name="366" href="#366">366</a> <em>         * Get character at passed absolute position.</em>
<a name="367" href="#367">367</a> <em>         *</em>
<a name="368" href="#368">368</a> <em>         * Called by {@link #charAt(int)} which has a relative index into the</em>
<a name="369" href="#369">369</a> <em>         * content, one that doesn't account for HTTP header if present.</em>
<a name="370" href="#370">370</a> <em>         *</em>
<a name="371" href="#371">371</a> <em>         * @param index Index into content adjusted to accomodate initial offset</em>
<a name="372" href="#372">372</a> <em>         * to get us past the HTTP header if present (i.e.</em>
<a name="373" href="#373">373</a> <em>         * {@link #contentOffset}).</em>
<a name="374" href="#374">374</a> <em>         *</em>
<a name="375" href="#375">375</a> <em>         * @return Characater at offset &lt;code>index&lt;/code>.</em>
<a name="376" href="#376">376</a> <em>         */</em>
<a name="377" href="#377">377</a>         <strong>public</strong> <strong>char</strong> <strong>char</strong>At(<strong>int</strong> index) {
<a name="378" href="#378">378</a>             <strong>int</strong> c = -1;
<a name="379" href="#379">379</a>             <em class="comment">// Add to index start-of-content offset to get us over HTTP header</em>
<a name="380" href="#380">380</a>             <em class="comment">// if present.</em>
<a name="381" href="#381">381</a>             index += <strong>this</strong>.contentOffset;
<a name="382" href="#382">382</a>             <strong>if</strong> (index &lt; <strong>this</strong>.prefixBuffer.length) {
<a name="383" href="#383">383</a>                 <em class="comment">// If index is into our prefix buffer.</em>
<a name="384" href="#384">384</a>                 c = <strong>this</strong>.prefixBuffer[index];
<a name="385" href="#385">385</a>             } <strong>else</strong> <strong>if</strong> (index >= <strong>this</strong>.wrapOrigin &amp;&amp;
<a name="386" href="#386">386</a>                 (index - <strong>this</strong>.wrapOrigin) &lt; <strong>this</strong>.wraparoundBuffer.length) {
<a name="387" href="#387">387</a>                 <em class="comment">// If index is into our buffer window on underlying backing file.</em>
<a name="388" href="#388">388</a>                 c = <strong>this</strong>.wraparoundBuffer[
<a name="389" href="#389">389</a>                         ((index - <strong>this</strong>.wrapOrigin) + <strong>this</strong>.wrapOffset) %
<a name="390" href="#390">390</a>                             <strong>this</strong>.wraparoundBuffer.length];
<a name="391" href="#391">391</a>             } <strong>else</strong> {
<a name="392" href="#392">392</a>                 <em class="comment">// Index is outside of both prefix buffer and our buffer window</em>
<a name="393" href="#393">393</a>                 <em class="comment">// onto the underlying backing file.  Fix the buffer window</em>
<a name="394" href="#394">394</a>                 <em class="comment">// location.</em>
<a name="395" href="#395">395</a>                 c = faultCharAt(index);
<a name="396" href="#396">396</a>             }
<a name="397" href="#397">397</a>             <em class="comment">// Stream is treated as single byte.  Make sure characters returned</em>
<a name="398" href="#398">398</a>             <em class="comment">// are not negative.</em>
<a name="399" href="#399">399</a>             <strong>return</strong> (<strong>char</strong>)(c &amp; 0xff);
<a name="400" href="#400">400</a>         }
<a name="401" href="#401">401</a> 
<a name="402" href="#402">402</a>         <em>/**<em>*</em></em>
<a name="403" href="#403">403</a> <em>         * Get a character that's outside the current buffers.</em>
<a name="404" href="#404">404</a> <em>         *</em>
<a name="405" href="#405">405</a> <em>         * will cause the wraparoundBuffer to be changed to</em>
<a name="406" href="#406">406</a> <em>         * cover a region including the index</em>
<a name="407" href="#407">407</a> <em>         *</em>
<a name="408" href="#408">408</a> <em>         * if index is higher than the highest index in the</em>
<a name="409" href="#409">409</a> <em>         * wraparound buffer, buffer is moved forward such</em>
<a name="410" href="#410">410</a> <em>         * that requested char is last item in buffer</em>
<a name="411" href="#411">411</a> <em>         *</em>
<a name="412" href="#412">412</a> <em>         * if index is lower than lowest index in the</em>
<a name="413" href="#413">413</a> <em>         * wraparound buffer, buffet is reset centered around</em>
<a name="414" href="#414">414</a> <em>         * index</em>
<a name="415" href="#415">415</a> <em>         *</em>
<a name="416" href="#416">416</a> <em>         * @param index Index of character to fetch.</em>
<a name="417" href="#417">417</a> <em>         * @return A character that's outside the current buffers</em>
<a name="418" href="#418">418</a> <em>         */</em>
<a name="419" href="#419">419</a>         <strong>private</strong> <strong>int</strong> faultCharAt(<strong>int</strong> index) {
<a name="420" href="#420">420</a>             <strong>if</strong>(Thread.interrupted()) {
<a name="421" href="#421">421</a>                 <strong>throw</strong> <strong>new</strong> RuntimeException(<span class="string">"thread interrupted"</span>);
<a name="422" href="#422">422</a>             }
<a name="423" href="#423">423</a>             <strong>if</strong>(index >= <strong>this</strong>.wrapOrigin + <strong>this</strong>.wraparoundBuffer.length) {
<a name="424" href="#424">424</a>                 <em class="comment">// Moving forward</em>
<a name="425" href="#425">425</a>                 <strong>while</strong> (index >= <strong>this</strong>.wrapOrigin + <strong>this</strong>.wraparoundBuffer.length)
<a name="426" href="#426">426</a>                 {
<a name="427" href="#427">427</a>                     <em class="comment">// TODO optimize this</em>
<a name="428" href="#428">428</a>                     advanceBuffer();
<a name="429" href="#429">429</a>                 }
<a name="430" href="#430">430</a>                 <strong>return</strong> charAt(index - <strong>this</strong>.contentOffset);
<a name="431" href="#431">431</a>             }
<a name="432" href="#432">432</a>             <em class="comment">// Moving backward</em>
<a name="433" href="#433">433</a>             recenterBuffer(index);
<a name="434" href="#434">434</a>             <strong>return</strong> charAt(index - <strong>this</strong>.contentOffset);
<a name="435" href="#435">435</a>         }