httpconnection.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="475" href="#475">475</a> 
<a name="476" href="#476">476</a>     <em>/**<em>*</em></em>
<a name="477" href="#477">477</a> <em>     * Determines whether this connection is "stale", which is to say that either</em>
<a name="478" href="#478">478</a> <em>     * it is no longer open, or an attempt to read the connection would fail.</em>
<a name="479" href="#479">479</a> <em>     *</em>
<a name="480" href="#480">480</a> <em>     * &lt;p>Unfortunately, due to the limitations of the JREs prior to 1.4, it is</em>
<a name="481" href="#481">481</a> <em>     * not possible to test a connection to see if both the read and write channels</em>
<a name="482" href="#482">482</a> <em>     * are open - except by reading and writing.  This leads to a difficulty when</em>
<a name="483" href="#483">483</a> <em>     * some connections leave the "write" channel open, but close the read channel</em>
<a name="484" href="#484">484</a> <em>     * and ignore the request.  This function attempts to ameliorate that</em>
<a name="485" href="#485">485</a> <em>     * problem by doing a test read, assuming that the caller will be doing a</em>
<a name="486" href="#486">486</a> <em>     * write followed by a read, rather than the other way around.</em>
<a name="487" href="#487">487</a> <em>     * &lt;/p></em>
<a name="488" href="#488">488</a> <em>     *</em>
<a name="489" href="#489">489</a> <em>     * &lt;p>To avoid side-effects, the underlying connection is wrapped by a</em>
<a name="490" href="#490">490</a> <em>     * {@link BufferedInputStream}, so although data might be read, what is visible</em>
<a name="491" href="#491">491</a> <em>     * to clients of the connection will not change with this call.&lt;/p.</em>
<a name="492" href="#492">492</a> <em>     *</em>
<a name="493" href="#493">493</a> <em>     * @throws IOException if the stale connection test is interrupted.</em>
<a name="494" href="#494">494</a> <em>     * </em>
<a name="495" href="#495">495</a> <em>     * @return &lt;tt>true&lt;/tt> if the connection is already closed, or a read would</em>
<a name="496" href="#496">496</a> <em>     * fail.</em>
<a name="497" href="#497">497</a> <em>     */</em>
<a name="498" href="#498">498</a>     <strong>protected</strong> <strong>boolean</strong> isStale() throws IOException {
<a name="499" href="#499">499</a>         <strong>boolean</strong> isStale = <strong>true</strong>;
<a name="500" href="#500">500</a>         <strong>if</strong> (isOpen) {
<a name="501" href="#501">501</a>             <em class="comment">// the connection is open, but now we have to see if we can read it</em>
<a name="502" href="#502">502</a>             <em class="comment">// assume the connection is not stale.</em>
<a name="503" href="#503">503</a>             isStale = false;
<a name="504" href="#504">504</a>             <strong>try</strong> {
<a name="505" href="#505">505</a>                 <strong>if</strong> (inputStream.available() &lt;= 0) {
<a name="506" href="#506">506</a>                     <strong>try</strong> {
<a name="507" href="#507">507</a>                         socket.setSoTimeout(1);
<a name="508" href="#508">508</a>                         inputStream.mark(1);
<a name="509" href="#509">509</a>                         <strong>int</strong> byteRead = inputStream.read();
<a name="510" href="#510">510</a>                         <strong>if</strong> (byteRead == -1) {
<a name="511" href="#511">511</a>                             <em class="comment">// again - if the socket is reporting all data read,</em>
<a name="512" href="#512">512</a>                             <em class="comment">// probably stale</em>
<a name="513" href="#513">513</a>                             isStale = <strong>true</strong>;
<a name="514" href="#514">514</a>                         } <strong>else</strong> {
<a name="515" href="#515">515</a>                             inputStream.reset();
<a name="516" href="#516">516</a>                         }
<a name="517" href="#517">517</a>                     } <strong>finally</strong> {
<a name="518" href="#518">518</a>                         socket.setSoTimeout(<strong>this</strong>.params.getSoTimeout());
<a name="519" href="#519">519</a>                     }
<a name="520" href="#520">520</a>                 }
<a name="521" href="#521">521</a>             } <strong>catch</strong> (InterruptedIOException e) {
<a name="522" href="#522">522</a>                 <strong>if</strong> (!ExceptionUtil.isSocketTimeoutException(e)) {
<a name="523" href="#523">523</a>                     <strong>throw</strong> e;
<a name="524" href="#524">524</a>                 }
<a name="525" href="#525">525</a>                 <em class="comment">// aha - the connection is NOT stale - continue on!</em>
<a name="526" href="#526">526</a>             } <strong>catch</strong> (IOException e) {
<a name="527" href="#527">527</a>                 <em class="comment">// oops - the connection is stale, the read or soTimeout failed.</em>
<a name="528" href="#528">528</a>                 LOG.debug(
<a name="529" href="#529">529</a>                     <span class="string">"An error occurred while reading from the socket, is appears to be stale"</span>,
<a name="530" href="#530">530</a>                     e
<a name="531" href="#531">531</a>                 );
<a name="532" href="#532">532</a>                 isStale = <strong>true</strong>;
<a name="533" href="#533">533</a>             }
<a name="534" href="#534">534</a>         }
<a name="535" href="#535">535</a> 
<a name="536" href="#536">536</a>         <strong>return</strong> isStale;
<a name="537" href="#537">537</a>     }
<a name="538" href="#538">538</a> 
<a name="539" href="#539">539</a>     <em>/**<em>*</em></em>
<a name="540" href="#540">540</a> <em>     * Returns &lt;tt>true&lt;/tt> if the connection is established via a proxy,</em>
<a name="541" href="#541">541</a> <em>     * &lt;tt>false&lt;/tt> otherwise.</em>
<a name="542" href="#542">542</a> <em>     *</em>
<a name="543" href="#543">543</a> <em>     * @return &lt;tt>true&lt;/tt> if a proxy is used to establish the connection, </em>
<a name="544" href="#544">544</a> <em>     * &lt;tt>false&lt;/tt> otherwise.</em>
<a name="545" href="#545">545</a> <em>     */</em>
<a name="546" href="#546">546</a>     <strong>public</strong> <strong>boolean</strong> isProxied() {
<a name="547" href="#547">547</a>         <strong>return</strong> (!(<strong>null</strong> == proxyHostName || 0 >= proxyPortNumber));
<a name="548" href="#548">548</a>     }
<a name="549" href="#549">549</a> 
<a name="550" href="#550">550</a>     <em>/**<em>*</em></em>
<a name="551" href="#551">551</a> <em>     * Set the state to keep track of the last response for the last request.</em>
<a name="552" href="#552">552</a> <em>     *</em>
<a name="553" href="#553">553</a> <em>     * &lt;p>The connection managers use this to ensure that previous requests are</em>
<a name="554" href="#554">554</a> <em>     * properly closed before a new request is attempted.  That way, a GET</em>
<a name="555" href="#555">555</a> <em>     * request need not be read in its entirety before a new request is issued.</em>
<a name="556" href="#556">556</a> <em>     * Instead, this stream can be closed as appropriate.&lt;/p></em>
<a name="557" href="#557">557</a> <em>     *</em>
<a name="558" href="#558">558</a> <em>     * @param inStream  The stream associated with an HttpMethod.</em>
<a name="559" href="#559">559</a> <em>     */</em>
<a name="560" href="#560">560</a>     <strong>public</strong> <strong>void</strong> setLastResponseInputStream(InputStream inStream) {
<a name="561" href="#561">561</a>         lastResponseInputStream = inStream;
<a name="562" href="#562">562</a>     }
<a name="563" href="#563">563</a> 
<a name="564" href="#564">564</a>     <em>/**<em>*</em></em>
<a name="565" href="#565">565</a> <em>     * Returns the stream used to read the last response's body.</em>
<a name="566" href="#566">566</a> <em>     *</em>
<a name="567" href="#567">567</a> <em>     * &lt;p>Clients will generally not need to call this function unless</em>
<a name="568" href="#568">568</a> <em>     * using HttpConnection directly, instead of calling {@link HttpClient#executeMethod}.</em>
<a name="569" href="#569">569</a> <em>     * For those clients, call this function, and if it returns a non-null stream,</em>
<a name="570" href="#570">570</a> <em>     * close the stream before attempting to execute a method.  Note that</em>
<a name="571" href="#571">571</a> <em>     * calling "close" on the stream returned by this function &lt;i>may&lt;/i> close</em>
<a name="572" href="#572">572</a> <em>     * the connection if the previous response contained a "Connection: close" header. &lt;/p></em>
<a name="573" href="#573">573</a> <em>     *</em>
<a name="574" href="#574">574</a> <em>     * @return An {@link InputStream} corresponding to the body of the last</em>
<a name="575" href="#575">575</a> <em>     *  response.</em>
<a name="576" href="#576">576</a> <em>     */</em>
<a name="577" href="#577">577</a>     <strong>public</strong> InputStream getLastResponseInputStream() {
<a name="578" href="#578">578</a>         <strong>return</strong> lastResponseInputStream;
<a name="579" href="#579">579</a>     }
<a name="580" href="#580">580</a> 
<a name="581" href="#581">581</a>     <em class="comment">// --------------------------------------------------- Other Public Methods</em>
<a name="582" href="#582">582</a> 
<a name="583" href="#583">583</a>     <em>/**<em>*</em></em>
<a name="584" href="#584">584</a> <em>     * Returns {@link HttpConnectionParams HTTP protocol parameters} associated with this method.</em>
<a name="585" href="#585">585</a> <em>     *</em>
<a name="586" href="#586">586</a> <em>     * @return HTTP parameters.</em>
<a name="587" href="#587">587</a> <em>     *</em>
<a name="588" href="#588">588</a> <em>     * @since 3.0</em>
<a name="589" href="#589">589</a> <em>     */</em>
<a name="590" href="#590">590</a>     <strong>public</strong> HttpConnectionParams getParams() {
<a name="591" href="#591">591</a>         <strong>return</strong> <strong>this</strong>.params;
<a name="592" href="#592">592</a>     }
<a name="593" href="#593">593</a> 
<a name="594" href="#594">594</a>     <em>/**<em>*</em></em>
<a name="595" href="#595">595</a> <em>     * Assigns {@link HttpConnectionParams HTTP protocol parameters} for this method.</em>
<a name="596" href="#596">596</a> <em>     * </em>
<a name="597" href="#597">597</a> <em>     * @since 3.0</em>
<a name="598" href="#598">598</a> <em>     * </em>
<a name="599" href="#599">599</a> <em>     * @see HttpConnectionParams</em>
<a name="600" href="#600">600</a> <em>     */</em>
<a name="601" href="#601">601</a>     <strong>public</strong> <strong>void</strong> setParams(<strong>final</strong> HttpConnectionParams params) {
<a name="602" href="#602">602</a>         <strong>if</strong> (params == <strong>null</strong>) {
<a name="603" href="#603">603</a>             <strong>throw</strong> <strong>new</strong> IllegalArgumentException(<span class="string">"Parameters may not be null"</span>);
<a name="604" href="#604">604</a>         }
<a name="605" href="#605">605</a>         <strong>this</strong>.params = params;
<a name="606" href="#606">606</a>     }
<a name="607" href="#607">607</a> 
<a name="608" href="#608">608</a>     <em>/**<em>*</em></em>
<a name="609" href="#609">609</a> <em>     * Set the {@link Socket}'s timeout, via {@link Socket#setSoTimeout}.  If the</em>
<a name="610" href="#610">610</a> <em>     * connection is already open, the SO_TIMEOUT is changed.  If no connection</em>
<a name="611" href="#611">611</a> <em>     * is open, then subsequent connections will use the timeout value.</em>
<a name="612" href="#612">612</a> <em>     * &lt;p></em>
<a name="613" href="#613">613</a> <em>     * Note: This is not a connection timeout but a timeout on network traffic!</em>
<a name="614" href="#614">614</a> <em>     *</em>
<a name="615" href="#615">615</a> <em>     * @param timeout the timeout value</em>
<a name="616" href="#616">616</a> <em>     * @throws SocketException - if there is an error in the underlying</em>
<a name="617" href="#617">617</a> <em>     * protocol, such as a TCP error.</em>
<a name="618" href="#618">618</a> <em>     * </em>
<a name="619" href="#619">619</a> <em>     * @deprecated Use {@link HttpConnectionParams#setSoTimeout(int)},</em>
<a name="620" href="#620">620</a> <em>     * {@link HttpConnection#getParams()}.</em>
<a name="621" href="#621">621</a> <em>     */</em>
<a name="622" href="#622">622</a>     <strong>public</strong> <strong>void</strong> setSoTimeout(<strong>int</strong> timeout)
<a name="623" href="#623">623</a>         throws SocketException, IllegalStateException {
<a name="624" href="#624">624</a>         <strong>this</strong>.params.setSoTimeout(timeout);
<a name="625" href="#625">625</a>         <strong>if</strong> (<strong>this</strong>.socket != <strong>null</strong>) {
<a name="626" href="#626">626</a>             <strong>this</strong>.socket.setSoTimeout(timeout);
<a name="627" href="#627">627</a>         }
<a name="628" href="#628">628</a>     }
<a name="629" href="#629">629</a> 
<a name="630" href="#630">630</a>     <em>/**<em>*</em></em>
<a name="631" href="#631">631</a> <em>     * Sets &lt;code>SO_TIMEOUT&lt;/code> value directly on the underlying {@link Socket socket}. </em>
<a name="632" href="#632">632</a> <em>     * This method does not change the default read timeout value set via </em>
<a name="633" href="#633">633</a> <em>     * {@link HttpConnectionParams}.</em>
<a name="634" href="#634">634</a> <em>     *</em>
<a name="635" href="#635">635</a> <em>     * @param timeout the timeout value</em>