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="436" href="#436">436</a> 
<a name="437" href="#437">437</a>         <em>/**<em>*</em></em>
<a name="438" href="#438">438</a> <em>         * Move the buffer window on backing file back centering current access</em>
<a name="439" href="#439">439</a> <em>         * position in middle of window.</em>
<a name="440" href="#440">440</a> <em>         *</em>
<a name="441" href="#441">441</a> <em>         * @param index Index of character to access.</em>
<a name="442" href="#442">442</a> <em>         */</em>
<a name="443" href="#443">443</a>         <strong>private</strong> <strong>void</strong> recenterBuffer(<strong>int</strong> index) {
<a name="444" href="#444">444</a>             <strong>if</strong> (logger.isLoggable(Level.FINE)) {
<a name="445" href="#445">445</a>                 logger.fine(<span class="string">"Recentering around "</span> + index + <span class="string">" in "</span> +
<a name="446" href="#446">446</a>                     <strong>this</strong>.backingFilename);
<a name="447" href="#447">447</a>             }
<a name="448" href="#448">448</a>             <strong>this</strong>.wrapOrigin = index - (<strong>this</strong>.wraparoundBuffer.length / 2);
<a name="449" href="#449">449</a>             <strong>if</strong>(<strong>this</strong>.wrapOrigin &lt; <strong>this</strong>.prefixBuffer.length) {
<a name="450" href="#450">450</a>                 <strong>this</strong>.wrapOrigin = <strong>this</strong>.prefixBuffer.length;
<a name="451" href="#451">451</a>             }
<a name="452" href="#452">452</a>             <strong>this</strong>.wrapOffset = 0;
<a name="453" href="#453">453</a>             loadBuffer();
<a name="454" href="#454">454</a>         }
<a name="455" href="#455">455</a> 
<a name="456" href="#456">456</a>         <em>/**<em>*</em></em>
<a name="457" href="#457">457</a> <em>         * Load from backing file into the wrapper buffer.</em>
<a name="458" href="#458">458</a> <em>         */</em>
<a name="459" href="#459">459</a>         <strong>private</strong> <strong>void</strong> loadBuffer()
<a name="460" href="#460">460</a>         {
<a name="461" href="#461">461</a>             <strong>long</strong> len = -1;
<a name="462" href="#462">462</a>             <strong>try</strong> {
<a name="463" href="#463">463</a>                 len = <strong>this</strong>.raFile.length();
<a name="464" href="#464">464</a>                 <strong>this</strong>.raFile.seek(<strong>this</strong>.wrapOrigin - <strong>this</strong>.prefixBuffer.length);
<a name="465" href="#465">465</a>                 <strong>this</strong>.raFile.readFully(<strong>this</strong>.wraparoundBuffer, 0,
<a name="466" href="#466">466</a>                     Math.min(<strong>this</strong>.wraparoundBuffer.length,
<a name="467" href="#467">467</a>                          <strong>this</strong>.absoluteLength - <strong>this</strong>.wrapOrigin));
<a name="468" href="#468">468</a>             }
<a name="469" href="#469">469</a> 
<a name="470" href="#470">470</a>             <strong>catch</strong> (IOException e) {
<a name="471" href="#471">471</a>                 <em class="comment">// TODO convert this to a runtime error?</em>
<a name="472" href="#472">472</a>                 DevUtils.logger.log (
<a name="473" href="#473">473</a>                     Level.SEVERE,
<a name="474" href="#474">474</a>                     <span class="string">"raFile.seek("</span> +
<a name="475" href="#475">475</a>                     (<strong>this</strong>.wrapOrigin - <strong>this</strong>.prefixBuffer.length) +
<a name="476" href="#476">476</a>                     <span class="string">")\n"</span> +
<a name="477" href="#477">477</a>                     <span class="string">"raFile.readFully(wraparoundBuffer,0,"</span> +
<a name="478" href="#478">478</a>                     (Math.min(<strong>this</strong>.wraparoundBuffer.length,
<a name="479" href="#479">479</a>                         <strong>this</strong>.length - <strong>this</strong>.wrapOrigin )) +
<a name="480" href="#480">480</a>                     <span class="string">")\n"</span>+
<a name="481" href="#481">481</a>                     <span class="string">"raFile.length()"</span> + len + <span class="string">"\n"</span> +
<a name="482" href="#482">482</a>                     DevUtils.extraInfo(),
<a name="483" href="#483">483</a>                     e);
<a name="484" href="#484">484</a>                 <strong>throw</strong> <strong>new</strong> RuntimeException(e);
<a name="485" href="#485">485</a>             }
<a name="486" href="#486">486</a>         }
<a name="487" href="#487">487</a> 
<a name="488" href="#488">488</a>         <em>/**<em>*</em></em>
<a name="489" href="#489">489</a> <em>         * Roll the wraparound buffer forward one position</em>
<a name="490" href="#490">490</a> <em>         */</em>
<a name="491" href="#491">491</a>         <strong>private</strong> <strong>void</strong> advanceBuffer() {
<a name="492" href="#492">492</a>             <strong>try</strong> {
<a name="493" href="#493">493</a>                 <strong>this</strong>.wraparoundBuffer[<strong>this</strong>.wrapOffset] =
<a name="494" href="#494">494</a>                     (byte)<strong>this</strong>.raFile.read();
<a name="495" href="#495">495</a>                 <strong>this</strong>.wrapOffset++;
<a name="496" href="#496">496</a>                 <strong>this</strong>.wrapOffset %= <strong>this</strong>.wraparoundBuffer.length;
<a name="497" href="#497">497</a>                 <strong>this</strong>.wrapOrigin++;
<a name="498" href="#498">498</a>             } <strong>catch</strong> (IOException e) {
<a name="499" href="#499">499</a>                 DevUtils.logger.log(Level.SEVERE, <span class="string">"advanceBuffer()"</span> +
<a name="500" href="#500">500</a>                     DevUtils.extraInfo(), e);
<a name="501" href="#501">501</a>                 <strong>throw</strong> <strong>new</strong> RuntimeException(e);
<a name="502" href="#502">502</a>             }
<a name="503" href="#503">503</a>         }
<a name="504" href="#504">504</a> 
<a name="505" href="#505">505</a>         <strong>public</strong> CharSequence subSequence(<strong>int</strong> start, <strong>int</strong> end) {
<a name="506" href="#506">506</a>             <strong>return</strong> <strong>new</strong> <a href="../../../org/archive/io/CharSubSequence.html">CharSubSequence</a>(<strong>this</strong>, start, end);
<a name="507" href="#507">507</a>         }
<a name="508" href="#508">508</a> 
<a name="509" href="#509">509</a>         <em>/**<em>*</em></em>
<a name="510" href="#510">510</a> <em>         * Cleanup resources.</em>
<a name="511" href="#511">511</a> <em>         *</em>
<a name="512" href="#512">512</a> <em>         * @exception IOException Failed close of random access file.</em>
<a name="513" href="#513">513</a> <em>         */</em>
<a name="514" href="#514">514</a>         <strong>public</strong> <strong>void</strong> close() throws IOException
<a name="515" href="#515">515</a>         {
<a name="516" href="#516">516</a>             <strong>this</strong>.prefixBuffer = <strong>null</strong>;
<a name="517" href="#517">517</a>             <strong>if</strong> (<strong>this</strong>.raFile != <strong>null</strong>) {
<a name="518" href="#518">518</a>                 <strong>this</strong>.raFile.close();
<a name="519" href="#519">519</a>                 <strong>this</strong>.raFile = <strong>null</strong>;
<a name="520" href="#520">520</a>             }
<a name="521" href="#521">521</a>         }
<a name="522" href="#522">522</a> 
<a name="523" href="#523">523</a>         <em class="comment">/*<em class="comment"> (non-Javadoc)</em></em>
<a name="524" href="#524">524</a> <em class="comment">         * @see java.lang.Object#finalize()</em>
<a name="525" href="#525">525</a> <em class="comment">         */</em>
<a name="526" href="#526">526</a>         <strong>protected</strong> <strong>void</strong> finalize() throws Throwable
<a name="527" href="#527">527</a>         {
<a name="528" href="#528">528</a>             <strong>super</strong>.finalize();
<a name="529" href="#529">529</a>             close();
<a name="530" href="#530">530</a>         }
<a name="531" href="#531">531</a> 
<a name="532" href="#532">532</a>         <em class="comment">/*<em class="comment"> (non-Javadoc)</em></em>
<a name="533" href="#533">533</a> <em class="comment">         * @see org.archive.io.EnhancedCharSequence#substring(int, int)</em>
<a name="534" href="#534">534</a> <em class="comment">         */</em>
<a name="535" href="#535">535</a>         <strong>public</strong> String substring(<strong>int</strong> offset, <strong>int</strong> len) {
<a name="536" href="#536">536</a>             StringBuffer ret = <strong>new</strong> StringBuffer(len);
<a name="537" href="#537">537</a>             <em class="comment">// Add to offset start-of-content offset to get us over HTTP header</em>
<a name="538" href="#538">538</a>             <em class="comment">// if present.</em>
<a name="539" href="#539">539</a>             offset += <strong>this</strong>.contentOffset;
<a name="540" href="#540">540</a>             <strong>if</strong> (offset &lt; <strong>this</strong>.prefixBuffer.length) {
<a name="541" href="#541">541</a>                 <em class="comment">// Need something from the prefix buffer.</em>
<a name="542" href="#542">542</a>                 <strong>int</strong> from = offset;
<a name="543" href="#543">543</a>                 <em class="comment">// To the end of the buffer</em>
<a name="544" href="#544">544</a>                 <strong>int</strong> count = <strong>this</strong>.prefixBuffer.length - from;
<a name="545" href="#545">545</a>                 <strong>if</strong> (offset + len &lt; <strong>this</strong>.prefixBuffer.length) {
<a name="546" href="#546">546</a>                     count = len; <em class="comment">// length falls within the buffer.</em>
<a name="547" href="#547">547</a>                 } <strong>else</strong> {
<a name="548" href="#548">548</a>                     <em class="comment">// Will need more then is in the prefixBuffer.</em>
<a name="549" href="#549">549</a>                     offset = <strong>this</strong>.prefixBuffer.length + 1;
<a name="550" href="#550">550</a>                     len = len - count;
<a name="551" href="#551">551</a>                 }
<a name="552" href="#552">552</a>                 <em class="comment">// Since we are dealing with a byte buffer we'll have to use</em>
<a name="553" href="#553">553</a>                 <em class="comment">// a String and then wrap up in a StringBuffer to concat with</em>
<a name="554" href="#554">554</a>                 <em class="comment">// the backing file. TODO: This can probably be optimized.</em>
<a name="555" href="#555">555</a>                 <em class="comment">//</em>
<a name="556" href="#556">556</a>                 <em class="comment">// Also, force an 8-bit encoding.  Default jvm encoding is</em>
<a name="557" href="#557">557</a>                 <em class="comment">// usually -- us context -- 7 bit ascii.  If we don't force</em>
<a name="558" href="#558">558</a>                 <em class="comment">// 8-bit, characters above 127 are considered rubbish.</em>
<a name="559" href="#559">559</a>                 <strong>try</strong> {
<a name="560" href="#560">560</a>                     ret.append(<strong>new</strong> String(<strong>this</strong>.prefixBuffer,from,count,
<a name="561" href="#561">561</a>                         DEFAULT_SINGLE_BYTE_ENCODING));
<a name="562" href="#562">562</a>                 }
<a name="563" href="#563">563</a>                 <strong>catch</strong> (UnsupportedEncodingException e) {
<a name="564" href="#564">564</a>                     logger.severe(<span class="string">"Failed encoding string: "</span> + e.getMessage());
<a name="565" href="#565">565</a>                 }
<a name="566" href="#566">566</a>             }
<a name="567" href="#567">567</a>             <strong>if</strong> (offset >= <strong>this</strong>.prefixBuffer.length) {
<a name="568" href="#568">568</a>                 <em class="comment">// TODO: Maybe better performance can be gained by reading</em>
<a name="569" href="#569">569</a>                 <em class="comment">// blocks from files.</em>
<a name="570" href="#570">570</a>                 <strong>int</strong> to = offset + len;
<a name="571" href="#571">571</a>                 <strong>for</strong>(<strong>int</strong> i = offset ; i &lt; to ; i++) {
<a name="572" href="#572">572</a>                     ret.append(charAt(i - <strong>this</strong>.contentOffset));
<a name="573" href="#573">573</a>                 }
<a name="574" href="#574">574</a>             }
<a name="575" href="#575">575</a> 
<a name="576" href="#576">576</a>             <strong>return</strong> ret.toString();
<a name="577" href="#577">577</a>         }
<a name="578" href="#578">578</a>         
<a name="579" href="#579">579</a>         <strong>public</strong> String toString() {
<a name="580" href="#580">580</a>             <strong>return</strong> substring(0, length());
<a name="581" href="#581">581</a>         }
<a name="582" href="#582">582</a>     }
<a name="583" href="#583">583</a>