fileutils.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="340" href="#340">340</a> <em>     * @param dir</em>
<a name="341" href="#341">341</a> <em>     * @return true if all deletions were successful. If a deletion fails, the</em>
<a name="342" href="#342">342</a> <em>     *          method stops attempting to delete and returns false.</em>
<a name="343" href="#343">343</a> <em>     */</em>
<a name="344" href="#344">344</a>     <strong>public</strong> <strong>static</strong> <strong>boolean</strong> deleteDir(File dir) {
<a name="345" href="#345">345</a>         <strong>if</strong> (dir.isDirectory()) {
<a name="346" href="#346">346</a>             String[] children = dir.list();
<a name="347" href="#347">347</a>             <strong>for</strong> (<strong>int</strong> i=0; i&lt;children.length; i++) {
<a name="348" href="#348">348</a>                 <strong>boolean</strong> success = deleteDir(<strong>new</strong> File(dir, children[i]));
<a name="349" href="#349">349</a>                 <strong>if</strong> (!success) {
<a name="350" href="#350">350</a>                     <strong>return</strong> false;
<a name="351" href="#351">351</a>                 }
<a name="352" href="#352">352</a>             }
<a name="353" href="#353">353</a>         }
<a name="354" href="#354">354</a>         <em class="comment">// The directory is now empty so delete it</em>
<a name="355" href="#355">355</a>         <strong>return</strong> dir.delete();
<a name="356" href="#356">356</a>     }
<a name="357" href="#357">357</a> 
<a name="358" href="#358">358</a> 
<a name="359" href="#359">359</a> 
<a name="360" href="#360">360</a>     <em>/**<em>*</em></em>
<a name="361" href="#361">361</a> <em>     * Utility method to read an entire file as a String.</em>
<a name="362" href="#362">362</a> <em>     *</em>
<a name="363" href="#363">363</a> <em>     * @param file</em>
<a name="364" href="#364">364</a> <em>     * @return File as String.</em>
<a name="365" href="#365">365</a> <em>     * @throws IOException</em>
<a name="366" href="#366">366</a> <em>     */</em>
<a name="367" href="#367">367</a>     <strong>public</strong> <strong>static</strong> String readFileAsString(File file) throws IOException {
<a name="368" href="#368">368</a>         StringBuffer sb = <strong>new</strong> StringBuffer((<strong>int</strong>) file.length());
<a name="369" href="#369">369</a>         String line;
<a name="370" href="#370">370</a>         BufferedReader br = <strong>new</strong> BufferedReader(<strong>new</strong> InputStreamReader(
<a name="371" href="#371">371</a>         		<strong>new</strong> FileInputStream(file)));
<a name="372" href="#372">372</a>         <strong>try</strong> {
<a name="373" href="#373">373</a>         	    line = br.readLine();
<a name="374" href="#374">374</a>         	    <strong>while</strong> (line != <strong>null</strong>) {
<a name="375" href="#375">375</a>         	    	    sb.append(line);
<a name="376" href="#376">376</a>                         sb.append(<span class="string">"\n"</span>);
<a name="377" href="#377">377</a>         	    	    line = br.readLine();
<a name="378" href="#378">378</a>         	    }
<a name="379" href="#379">379</a>         } <strong>finally</strong> {
<a name="380" href="#380">380</a>         	    br.close();
<a name="381" href="#381">381</a>         }
<a name="382" href="#382">382</a>         <strong>return</strong> sb.toString();
<a name="383" href="#383">383</a>     }
<a name="384" href="#384">384</a> 
<a name="385" href="#385">385</a>     <em>/**<em>*</em></em>
<a name="386" href="#386">386</a> <em>     * Get a list of all files in directory that have passed prefix.</em>
<a name="387" href="#387">387</a> <em>     *</em>
<a name="388" href="#388">388</a> <em>     * @param dir Dir to look in.</em>
<a name="389" href="#389">389</a> <em>     * @param prefix Basename of files to look for. Compare is case insensitive.</em>
<a name="390" href="#390">390</a> <em>     *</em>
<a name="391" href="#391">391</a> <em>     * @return List of files in dir that start w/ passed basename.</em>
<a name="392" href="#392">392</a> <em>     */</em>
<a name="393" href="#393">393</a>     <strong>public</strong> <strong>static</strong> File [] getFilesWithPrefix(File dir, <strong>final</strong> String prefix) {
<a name="394" href="#394">394</a>         FileFilter prefixFilter = <strong>new</strong> FileFilter() {
<a name="395" href="#395">395</a>                 <strong>public</strong> <strong>boolean</strong> accept(File pathname)
<a name="396" href="#396">396</a>                 {
<a name="397" href="#397">397</a>                     <strong>return</strong> pathname.getName().toLowerCase().
<a name="398" href="#398">398</a>                         startsWith(prefix.toLowerCase());
<a name="399" href="#399">399</a>                 }
<a name="400" href="#400">400</a>             };
<a name="401" href="#401">401</a>         <strong>return</strong> dir.listFiles(prefixFilter);
<a name="402" href="#402">402</a>     }
<a name="403" href="#403">403</a> 
<a name="404" href="#404">404</a>     <em>/**<em>* Get a @link java.io.FileFilter that filters files based on a regular</em></em>
<a name="405" href="#405">405</a> <em>     * expression.</em>
<a name="406" href="#406">406</a> <em>     *</em>
<a name="407" href="#407">407</a> <em>     * @param regexp the regular expression the files must match.</em>
<a name="408" href="#408">408</a> <em>     * @return the newly created filter.</em>
<a name="409" href="#409">409</a> <em>     */</em>
<a name="410" href="#410">410</a>     <strong>public</strong> <strong>static</strong> FileFilter getRegexpFileFilter(String regexp) {
<a name="411" href="#411">411</a>         <em class="comment">// Inner class defining the RegexpFileFilter</em>
<a name="412" href="#412">412</a>         <strong>class</strong> RegexpFileFilter implements FileFilter {
<a name="413" href="#413">413</a>             Pattern pattern;
<a name="414" href="#414">414</a> 
<a name="415" href="#415">415</a>             <strong>protected</strong> RegexpFileFilter(String re) {
<a name="416" href="#416">416</a>                 pattern = Pattern.compile(re);
<a name="417" href="#417">417</a>             }
<a name="418" href="#418">418</a> 
<a name="419" href="#419">419</a>             <strong>public</strong> <strong>boolean</strong> accept(File pathname) {
<a name="420" href="#420">420</a>                 <strong>return</strong> pattern.matcher(pathname.getName()).matches();
<a name="421" href="#421">421</a>             }
<a name="422" href="#422">422</a>         }
<a name="423" href="#423">423</a> 
<a name="424" href="#424">424</a>         <strong>return</strong> <strong>new</strong> RegexpFileFilter(regexp);
<a name="425" href="#425">425</a>     }
<a name="426" href="#426">426</a>     
<a name="427" href="#427">427</a>     <em>/**<em>*</em></em>
<a name="428" href="#428">428</a> <em>     * Use for case where files are being added to src.  Will break off copy</em>
<a name="429" href="#429">429</a> <em>     * when tgt is same as src.</em>
<a name="430" href="#430">430</a> <em>     * @param src Source directory to copy from.</em>
<a name="431" href="#431">431</a> <em>     * @param tgt Target to copy to.</em>
<a name="432" href="#432">432</a> <em>     * @param filter Filter to apply to files to copy.</em>
<a name="433" href="#433">433</a> <em>     * @throws IOException</em>
<a name="434" href="#434">434</a> <em>     */</em>
<a name="435" href="#435">435</a>     <strong>public</strong> <strong>static</strong> <strong>void</strong> syncDirectories(<strong>final</strong> File src,
<a name="436" href="#436">436</a>             <strong>final</strong> FilenameFilter filter, <strong>final</strong> File tgt)
<a name="437" href="#437">437</a>     throws IOException {
<a name="438" href="#438">438</a>         Set srcFilenames = <strong>null</strong>;
<a name="439" href="#439">439</a>         <strong>do</strong> {
<a name="440" href="#440">440</a>             srcFilenames = <strong>new</strong> HashSet(Arrays.asList(src.list(filter)));
<a name="441" href="#441">441</a>             List tgtFilenames = Arrays.asList(tgt.list(filter));
<a name="442" href="#442">442</a>             srcFilenames.removeAll(tgtFilenames);
<a name="443" href="#443">443</a>             <strong>if</strong> (srcFilenames.size() > 0) {
<a name="444" href="#444">444</a>                 <strong>int</strong> count = FileUtils.copyFiles(src, srcFilenames, tgt);
<a name="445" href="#445">445</a>                 <strong>if</strong> (LOGGER.isLoggable(Level.FINE)) {
<a name="446" href="#446">446</a>                     LOGGER.fine(<span class="string">"Copied "</span> + count);
<a name="447" href="#447">447</a>                 }
<a name="448" href="#448">448</a>             }
<a name="449" href="#449">449</a>         } <strong>while</strong> (srcFilenames != <strong>null</strong> &amp;&amp; srcFilenames.size() > 0);
<a name="450" href="#450">450</a>     }
<a name="451" href="#451">451</a>     
<a name="452" href="#452">452</a>     <em>/**<em>*</em></em>
<a name="453" href="#453">453</a> <em>     * Test file exists and is readable.</em>
<a name="454" href="#454">454</a> <em>     * @param f File to test.</em>
<a name="455" href="#455">455</a> <em>     * @exception IOException If file does not exist or is not unreadable.</em>
<a name="456" href="#456">456</a> <em>     */</em>
<a name="457" href="#457">457</a>     <strong>public</strong> <strong>static</strong> File isReadable(<strong>final</strong> File f) throws IOException {
<a name="458" href="#458">458</a>         <strong>if</strong> (!f.exists()) {
<a name="459" href="#459">459</a>             <strong>throw</strong> <strong>new</strong> FileNotFoundException(f.getAbsolutePath() +
<a name="460" href="#460">460</a>                 <span class="string">" does not exist."</span>);
<a name="461" href="#461">461</a>         }
<a name="462" href="#462">462</a> 
<a name="463" href="#463">463</a>         <strong>if</strong> (!f.canRead()) {
<a name="464" href="#464">464</a>             <strong>throw</strong> <strong>new</strong> FileNotFoundException(f.getAbsolutePath() +
<a name="465" href="#465">465</a>                 <span class="string">" is not readable."</span>);
<a name="466" href="#466">466</a>         }
<a name="467" href="#467">467</a>         
<a name="468" href="#468">468</a>         <strong>return</strong> f;
<a name="469" href="#469">469</a>     }
<a name="470" href="#470">470</a>     
<a name="471" href="#471">471</a>     <em>/**<em>*</em></em>
<a name="472" href="#472">472</a> <em>     * @param f File to test.</em>
<a name="473" href="#473">473</a> <em>     * @return True if file is readable, has uncompressed extension,</em>
<a name="474" href="#474">474</a> <em>     * and magic string at file start.</em>
<a name="475" href="#475">475</a> <em>     * @exception IOException If file does not exist or is not readable.</em>
<a name="476" href="#476">476</a> <em>     */</em>
<a name="477" href="#477">477</a>     <strong>public</strong> <strong>static</strong> <strong>boolean</strong> isReadableWithExtensionAndMagic(<strong>final</strong> File f, 
<a name="478" href="#478">478</a>             <strong>final</strong> String uncompressedExtension, <strong>final</strong> String magic)
<a name="479" href="#479">479</a>     throws IOException {
<a name="480" href="#480">480</a>         <strong>boolean</strong> result = false;
<a name="481" href="#481">481</a>         FileUtils.isReadable(f);
<a name="482" href="#482">482</a>         <strong>if</strong>(f.getName().toLowerCase().endsWith(uncompressedExtension)) {
<a name="483" href="#483">483</a>             FileInputStream fis = <strong>new</strong> FileInputStream(f);
<a name="484" href="#484">484</a>             <strong>try</strong> {
<a name="485" href="#485">485</a>                 byte [] b = <strong>new</strong> byte[magic.length()];
<a name="486" href="#486">486</a>                 <strong>int</strong> read = fis.read(b, 0, magic.length());
<a name="487" href="#487">487</a>                 fis.close();
<a name="488" href="#488">488</a>                 <strong>if</strong> (read == magic.length()) {
<a name="489" href="#489">489</a>                     StringBuffer beginStr
<a name="490" href="#490">490</a>                         = <strong>new</strong> StringBuffer(magic.length());
<a name="491" href="#491">491</a>                     <strong>for</strong> (<strong>int</strong> i = 0; i &lt; magic.length(); i++) {
<a name="492" href="#492">492</a>                         beginStr.append((<strong>char</strong>)b[i]);
<a name="493" href="#493">493</a>                     }
<a name="494" href="#494">494</a>                     
<a name="495" href="#495">495</a>                     <strong>if</strong> (beginStr.toString().
<a name="496" href="#496">496</a>                             equalsIgnoreCase(magic)) {
<a name="497" href="#497">497</a>                         result = <strong>true</strong>;
<a name="498" href="#498">498</a>                     }
<a name="499" href="#499">499</a>                 }
<a name="500" href="#500">500</a>             } <strong>finally</strong> {
<a name="501" href="#501">501</a>                 fis.close();
<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>return</strong> result;
<a name="506" href="#506">506</a>     }
<a name="507" href="#507">507</a> }
</pre>
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