diskfileitem.html

java 的上传功能很强大的实施上述事实上说是

<a name="402" href="#402">402</a> <em class="jxr_javadoccomment">     * This method is only guaranteed to work &lt;em&gt;once&lt;/em&gt;, the first time it</em>
<a name="403" href="#403">403</a> <em class="jxr_javadoccomment">     * is invoked for a particular item. This is because, in the event that the</em>
<a name="404" href="#404">404</a> <em class="jxr_javadoccomment">     * method renames a temporary file, that file will no longer be available</em>
<a name="405" href="#405">405</a> <em class="jxr_javadoccomment">     * to copy or rename again at a later time.</em>
<a name="406" href="#406">406</a> <em class="jxr_javadoccomment">     *</em>
<a name="407" href="#407">407</a> <em class="jxr_javadoccomment">     * @param file The &lt;code&gt;File&lt;/code&gt; into which the uploaded item should</em>
<a name="408" href="#408">408</a> <em class="jxr_javadoccomment">     *             be stored.</em>
<a name="409" href="#409">409</a> <em class="jxr_javadoccomment">     *</em>
<a name="410" href="#410">410</a> <em class="jxr_javadoccomment">     * @throws Exception if an error occurs.</em>
<a name="411" href="#411">411</a> <em class="jxr_javadoccomment">     */</em>
<a name="412" href="#412">412</a>     <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">void</strong> write(File file) <strong class="jxr_keyword">throws</strong> Exception {
<a name="413" href="#413">413</a>         <strong class="jxr_keyword">if</strong> (isInMemory()) {
<a name="414" href="#414">414</a>             FileOutputStream fout = <strong class="jxr_keyword">null</strong>;
<a name="415" href="#415">415</a>             <strong class="jxr_keyword">try</strong> {
<a name="416" href="#416">416</a>                 fout = <strong class="jxr_keyword">new</strong> FileOutputStream(file);
<a name="417" href="#417">417</a>                 fout.write(get());
<a name="418" href="#418">418</a>             } <strong class="jxr_keyword">finally</strong> {
<a name="419" href="#419">419</a>                 <strong class="jxr_keyword">if</strong> (fout != <strong class="jxr_keyword">null</strong>) {
<a name="420" href="#420">420</a>                     fout.close();
<a name="421" href="#421">421</a>                 }
<a name="422" href="#422">422</a>             }
<a name="423" href="#423">423</a>         } <strong class="jxr_keyword">else</strong> {
<a name="424" href="#424">424</a>             File outputFile = getStoreLocation();
<a name="425" href="#425">425</a>             <strong class="jxr_keyword">if</strong> (outputFile != <strong class="jxr_keyword">null</strong>) {
<a name="426" href="#426">426</a>                 <em class="jxr_comment">// Save the length of the file</em>
<a name="427" href="#427">427</a>                 size = outputFile.length();
<a name="428" href="#428">428</a>                 <em class="jxr_comment">/*</em>
<a name="429" href="#429">429</a> <em class="jxr_comment">                 * The uploaded file is being stored on disk</em>
<a name="430" href="#430">430</a> <em class="jxr_comment">                 * in a temporary location so move it to the</em>
<a name="431" href="#431">431</a> <em class="jxr_comment">                 * desired file.</em>
<a name="432" href="#432">432</a> <em class="jxr_comment">                 */</em>
<a name="433" href="#433">433</a>                 <strong class="jxr_keyword">if</strong> (!outputFile.renameTo(file)) {
<a name="434" href="#434">434</a>                     BufferedInputStream in = <strong class="jxr_keyword">null</strong>;
<a name="435" href="#435">435</a>                     BufferedOutputStream out = <strong class="jxr_keyword">null</strong>;
<a name="436" href="#436">436</a>                     <strong class="jxr_keyword">try</strong> {
<a name="437" href="#437">437</a>                         in = <strong class="jxr_keyword">new</strong> BufferedInputStream(
<a name="438" href="#438">438</a>                             <strong class="jxr_keyword">new</strong> FileInputStream(outputFile));
<a name="439" href="#439">439</a>                         out = <strong class="jxr_keyword">new</strong> BufferedOutputStream(
<a name="440" href="#440">440</a>                                 <strong class="jxr_keyword">new</strong> FileOutputStream(file));
<a name="441" href="#441">441</a>                         IOUtils.copy(in, out);
<a name="442" href="#442">442</a>                     } <strong class="jxr_keyword">finally</strong> {
<a name="443" href="#443">443</a>                         <strong class="jxr_keyword">if</strong> (in != <strong class="jxr_keyword">null</strong>) {
<a name="444" href="#444">444</a>                             <strong class="jxr_keyword">try</strong> {
<a name="445" href="#445">445</a>                                 in.close();
<a name="446" href="#446">446</a>                             } <strong class="jxr_keyword">catch</strong> (IOException e) {
<a name="447" href="#447">447</a>                                 <em class="jxr_comment">// ignore</em>
<a name="448" href="#448">448</a>                             }
<a name="449" href="#449">449</a>                         }
<a name="450" href="#450">450</a>                         <strong class="jxr_keyword">if</strong> (out != <strong class="jxr_keyword">null</strong>) {
<a name="451" href="#451">451</a>                             <strong class="jxr_keyword">try</strong> {
<a name="452" href="#452">452</a>                                 out.close();
<a name="453" href="#453">453</a>                             } <strong class="jxr_keyword">catch</strong> (IOException e) {
<a name="454" href="#454">454</a>                                 <em class="jxr_comment">// ignore</em>
<a name="455" href="#455">455</a>                             }
<a name="456" href="#456">456</a>                         }
<a name="457" href="#457">457</a>                     }
<a name="458" href="#458">458</a>                 }
<a name="459" href="#459">459</a>             } <strong class="jxr_keyword">else</strong> {
<a name="460" href="#460">460</a>                 <em class="jxr_comment">/*</em>
<a name="461" href="#461">461</a> <em class="jxr_comment">                 * For whatever reason we cannot write the</em>
<a name="462" href="#462">462</a> <em class="jxr_comment">                 * file to disk.</em>
<a name="463" href="#463">463</a> <em class="jxr_comment">                 */</em>
<a name="464" href="#464">464</a>                 <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> <a href="../../../../../org/apache/commons/fileupload/FileUploadException.html">FileUploadException</a>(
<a name="465" href="#465">465</a>                     <span class="jxr_string">"Cannot write uploaded file to disk!"</span>);
<a name="466" href="#466">466</a>             }
<a name="467" href="#467">467</a>         }
<a name="468" href="#468">468</a>     }
<a name="469" href="#469">469</a> 
<a name="470" href="#470">470</a> 
<a name="471" href="#471">471</a>     <em class="jxr_javadoccomment">/**</em>
<a name="472" href="#472">472</a> <em class="jxr_javadoccomment">     * Deletes the underlying storage for a file item, including deleting any</em>
<a name="473" href="#473">473</a> <em class="jxr_javadoccomment">     * associated temporary disk file. Although this storage will be deleted</em>
<a name="474" href="#474">474</a> <em class="jxr_javadoccomment">     * automatically when the &lt;code&gt;FileItem&lt;/code&gt; instance is garbage</em>
<a name="475" href="#475">475</a> <em class="jxr_javadoccomment">     * collected, this method can be used to ensure that this is done at an</em>
<a name="476" href="#476">476</a> <em class="jxr_javadoccomment">     * earlier time, thus preserving system resources.</em>
<a name="477" href="#477">477</a> <em class="jxr_javadoccomment">     */</em>
<a name="478" href="#478">478</a>     <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">void</strong> delete() {
<a name="479" href="#479">479</a>         cachedContent = <strong class="jxr_keyword">null</strong>;
<a name="480" href="#480">480</a>         File outputFile = getStoreLocation();
<a name="481" href="#481">481</a>         <strong class="jxr_keyword">if</strong> (outputFile != <strong class="jxr_keyword">null</strong> &amp;&amp; outputFile.exists()) {
<a name="482" href="#482">482</a>             outputFile.delete();
<a name="483" href="#483">483</a>         }
<a name="484" href="#484">484</a>     }
<a name="485" href="#485">485</a> 
<a name="486" href="#486">486</a> 
<a name="487" href="#487">487</a>     <em class="jxr_javadoccomment">/**</em>
<a name="488" href="#488">488</a> <em class="jxr_javadoccomment">     * Returns the name of the field in the multipart form corresponding to</em>
<a name="489" href="#489">489</a> <em class="jxr_javadoccomment">     * this file item.</em>
<a name="490" href="#490">490</a> <em class="jxr_javadoccomment">     *</em>
<a name="491" href="#491">491</a> <em class="jxr_javadoccomment">     * @return The name of the form field.</em>
<a name="492" href="#492">492</a> <em class="jxr_javadoccomment">     *</em>
<a name="493" href="#493">493</a> <em class="jxr_javadoccomment">     * @see #setFieldName(java.lang.String)</em>
<a name="494" href="#494">494</a> <em class="jxr_javadoccomment">     *</em>
<a name="495" href="#495">495</a> <em class="jxr_javadoccomment">     */</em>
<a name="496" href="#496">496</a>     <strong class="jxr_keyword">public</strong> String getFieldName() {
<a name="497" href="#497">497</a>         <strong class="jxr_keyword">return</strong> fieldName;
<a name="498" href="#498">498</a>     }
<a name="499" href="#499">499</a> 
<a name="500" href="#500">500</a> 
<a name="501" href="#501">501</a>     <em class="jxr_javadoccomment">/**</em>
<a name="502" href="#502">502</a> <em class="jxr_javadoccomment">     * Sets the field name used to reference this file item.</em>
<a name="503" href="#503">503</a> <em class="jxr_javadoccomment">     *</em>
<a name="504" href="#504">504</a> <em class="jxr_javadoccomment">     * @param fieldName The name of the form field.</em>
<a name="505" href="#505">505</a> <em class="jxr_javadoccomment">     *</em>
<a name="506" href="#506">506</a> <em class="jxr_javadoccomment">     * @see #getFieldName()</em>
<a name="507" href="#507">507</a> <em class="jxr_javadoccomment">     *</em>
<a name="508" href="#508">508</a> <em class="jxr_javadoccomment">     */</em>
<a name="509" href="#509">509</a>     <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">void</strong> setFieldName(String fieldName) {
<a name="510" href="#510">510</a>         <strong class="jxr_keyword">this</strong>.fieldName = fieldName;
<a name="511" href="#511">511</a>     }
<a name="512" href="#512">512</a> 
<a name="513" href="#513">513</a> 
<a name="514" href="#514">514</a>     <em class="jxr_javadoccomment">/**</em>
<a name="515" href="#515">515</a> <em class="jxr_javadoccomment">     * Determines whether or not a &lt;code&gt;FileItem&lt;/code&gt; instance represents</em>
<a name="516" href="#516">516</a> <em class="jxr_javadoccomment">     * a simple form field.</em>
<a name="517" href="#517">517</a> <em class="jxr_javadoccomment">     *</em>
<a name="518" href="#518">518</a> <em class="jxr_javadoccomment">     * @return &lt;code&gt;true&lt;/code&gt; if the instance represents a simple form</em>
<a name="519" href="#519">519</a> <em class="jxr_javadoccomment">     *         field; &lt;code&gt;false&lt;/code&gt; if it represents an uploaded file.</em>
<a name="520" href="#520">520</a> <em class="jxr_javadoccomment">     *</em>
<a name="521" href="#521">521</a> <em class="jxr_javadoccomment">     * @see #setFormField(boolean)</em>
<a name="522" href="#522">522</a> <em class="jxr_javadoccomment">     *</em>
<a name="523" href="#523">523</a> <em class="jxr_javadoccomment">     */</em>
<a name="524" href="#524">524</a>     <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">boolean</strong> isFormField() {
<a name="525" href="#525">525</a>         <strong class="jxr_keyword">return</strong> isFormField;
<a name="526" href="#526">526</a>     }
<a name="527" href="#527">527</a> 
<a name="528" href="#528">528</a> 
<a name="529" href="#529">529</a>     <em class="jxr_javadoccomment">/**</em>
<a name="530" href="#530">530</a> <em class="jxr_javadoccomment">     * Specifies whether or not a &lt;code&gt;FileItem&lt;/code&gt; instance represents</em>
<a name="531" href="#531">531</a> <em class="jxr_javadoccomment">     * a simple form field.</em>
<a name="532" href="#532">532</a> <em class="jxr_javadoccomment">     *</em>
<a name="533" href="#533">533</a> <em class="jxr_javadoccomment">     * @param state &lt;code&gt;true&lt;/code&gt; if the instance represents a simple form</em>
<a name="534" href="#534">534</a> <em class="jxr_javadoccomment">     *              field; &lt;code&gt;false&lt;/code&gt; if it represents an uploaded file.</em>
<a name="535" href="#535">535</a> <em class="jxr_javadoccomment">     *</em>
<a name="536" href="#536">536</a> <em class="jxr_javadoccomment">     * @see #isFormField()</em>
<a name="537" href="#537">537</a> <em class="jxr_javadoccomment">     *</em>
<a name="538" href="#538">538</a> <em class="jxr_javadoccomment">     */</em>