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| <div class="subTitle">jakarta.servlet</div> |
| <h2 title="Interface Servlet" class="title">Interface Servlet</h2> |
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| <dl> |
| <dt>All Known Subinterfaces:</dt> |
| <dd><a href="../../jakarta/servlet/jsp/HttpJspPage.html" title="interface in jakarta.servlet.jsp">HttpJspPage</a>, <a href="../../jakarta/servlet/jsp/JspPage.html" title="interface in jakarta.servlet.jsp">JspPage</a></dd> |
| </dl> |
| <dl> |
| <dt>All Known Implementing Classes:</dt> |
| <dd><a href="../../jakarta/servlet/GenericServlet.html" title="class in jakarta.servlet">GenericServlet</a>, <a href="../../jakarta/servlet/http/HttpServlet.html" title="class in jakarta.servlet.http">HttpServlet</a></dd> |
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| <pre>public interface <span class="typeNameLabel">Servlet</span></pre> |
| <div class="block">Defines methods that all servlets must implement. |
| |
| <p> |
| A servlet is a small Java program that runs within a Web server. Servlets receive and respond to requests from Web |
| clients, usually across HTTP, the HyperText Transfer Protocol. |
| |
| <p> |
| To implement this interface, you can write a generic servlet that extends <code>jakarta.servlet.GenericServlet</code> |
| or an HTTP servlet that extends <code>jakarta.servlet.http.HttpServlet</code>. |
| |
| <p> |
| This interface defines methods to initialize a servlet, to service requests, and to remove a servlet from the server. |
| These are known as life-cycle methods and are called in the following sequence: |
| <ol> |
| <li>The servlet is constructed, then initialized with the <code>init</code> method. |
| <li>Any calls from clients to the <code>service</code> method are handled. |
| <li>The servlet is taken out of service, then destroyed with the <code>destroy</code> method, then garbage collected |
| and finalized. |
| </ol> |
| |
| <p> |
| In addition to the life-cycle methods, this interface provides the <code>getServletConfig</code> method, which the |
| servlet can use to get any startup information, and the <code>getServletInfo</code> method, which allows the servlet |
| to return basic information about itself, such as author, version, and copyright.</div> |
| <dl> |
| <dt><span class="seeLabel">See Also:</span></dt> |
| <dd><a href="../../jakarta/servlet/GenericServlet.html" title="class in jakarta.servlet"><code>GenericServlet</code></a>, |
| <a href="../../jakarta/servlet/http/HttpServlet.html" title="class in jakarta.servlet.http"><code>HttpServlet</code></a></dd> |
| </dl> |
| </li> |
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| <h3>Method Summary</h3> |
| <table class="memberSummary" border="0" cellpadding="3" cellspacing="0" summary="Method Summary table, listing methods, and an explanation"> |
| <caption><span id="t0" class="activeTableTab"><span>All Methods</span><span class="tabEnd"> </span></span><span id="t2" class="tableTab"><span><a href="javascript:show(2);">Instance Methods</a></span><span class="tabEnd"> </span></span><span id="t3" class="tableTab"><span><a href="javascript:show(4);">Abstract Methods</a></span><span class="tabEnd"> </span></span></caption> |
| <tr> |
| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Method and Description</th> |
| </tr> |
| <tr id="i0" class="altColor"> |
| <td class="colFirst"><code>void</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../jakarta/servlet/Servlet.html#destroy--">destroy</a></span>()</code> |
| <div class="block">Called by the servlet container to indicate to a servlet that the servlet is being taken out of service.</div> |
| </td> |
| </tr> |
| <tr id="i1" class="rowColor"> |
| <td class="colFirst"><code><a href="../../jakarta/servlet/ServletConfig.html" title="interface in jakarta.servlet">ServletConfig</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../jakarta/servlet/Servlet.html#getServletConfig--">getServletConfig</a></span>()</code> |
| <div class="block">Returns a <a href="../../jakarta/servlet/ServletConfig.html" title="interface in jakarta.servlet"><code>ServletConfig</code></a> object, which contains initialization and startup parameters for this servlet.</div> |
| </td> |
| </tr> |
| <tr id="i2" class="altColor"> |
| <td class="colFirst"><code>java.lang.String</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../jakarta/servlet/Servlet.html#getServletInfo--">getServletInfo</a></span>()</code> |
| <div class="block">Returns information about the servlet, such as author, version, and copyright.</div> |
| </td> |
| </tr> |
| <tr id="i3" class="rowColor"> |
| <td class="colFirst"><code>void</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../jakarta/servlet/Servlet.html#init-jakarta.servlet.ServletConfig-">init</a></span>(<a href="../../jakarta/servlet/ServletConfig.html" title="interface in jakarta.servlet">ServletConfig</a> config)</code> |
| <div class="block">Called by the servlet container to indicate to a servlet that the servlet is being placed into service.</div> |
| </td> |
| </tr> |
| <tr id="i4" class="altColor"> |
| <td class="colFirst"><code>void</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../jakarta/servlet/Servlet.html#service-jakarta.servlet.ServletRequest-jakarta.servlet.ServletResponse-">service</a></span>(<a href="../../jakarta/servlet/ServletRequest.html" title="interface in jakarta.servlet">ServletRequest</a> req, |
| <a href="../../jakarta/servlet/ServletResponse.html" title="interface in jakarta.servlet">ServletResponse</a> res)</code> |
| <div class="block">Called by the servlet container to allow the servlet to respond to a request.</div> |
| </td> |
| </tr> |
| </table> |
| </li> |
| </ul> |
| </li> |
| </ul> |
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| </a> |
| <h3>Method Detail</h3> |
| <a name="init-jakarta.servlet.ServletConfig-"> |
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| <h4>init</h4> |
| <pre>void init(<a href="../../jakarta/servlet/ServletConfig.html" title="interface in jakarta.servlet">ServletConfig</a> config) |
| throws <a href="../../jakarta/servlet/ServletException.html" title="class in jakarta.servlet">ServletException</a></pre> |
| <div class="block">Called by the servlet container to indicate to a servlet that the servlet is being placed into service. |
| |
| <p> |
| The servlet container calls the <code>init</code> method exactly once after instantiating the servlet. The |
| <code>init</code> method must complete successfully before the servlet can receive any requests. The container will |
| ensure that actions performed in the <code>init</code> method will be visible to any threads that subsequently call |
| the <code>service</code> method according to the rules in JSR-133 (i.e. there is a 'happens before' relationship |
| between <code>init</code> and <code>service</code>). |
| |
| <p> |
| The servlet container cannot place the servlet into service if the <code>init</code> method |
| <ol> |
| <li>Throws a <code>ServletException</code> |
| <li>Does not return within a time period defined by the Web server |
| </ol></div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>config</code> - a <code>ServletConfig</code> object containing the servlet's configuration and initialization |
| parameters</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code><a href="../../jakarta/servlet/ServletException.html" title="class in jakarta.servlet">ServletException</a></code> - if an exception has occurred that interferes with the servlet's normal operation</dd> |
| <dt><span class="seeLabel">See Also:</span></dt> |
| <dd><a href="../../jakarta/servlet/UnavailableException.html" title="class in jakarta.servlet"><code>UnavailableException</code></a>, |
| <a href="../../jakarta/servlet/Servlet.html#getServletConfig--"><code>getServletConfig()</code></a></dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="getServletConfig--"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>getServletConfig</h4> |
| <pre><a href="../../jakarta/servlet/ServletConfig.html" title="interface in jakarta.servlet">ServletConfig</a> getServletConfig()</pre> |
| <div class="block">Returns a <a href="../../jakarta/servlet/ServletConfig.html" title="interface in jakarta.servlet"><code>ServletConfig</code></a> object, which contains initialization and startup parameters for this servlet. The |
| <code>ServletConfig</code> object returned is the one passed to the <code>init</code> method. |
| |
| <p> |
| Implementations of this interface are responsible for storing the <code>ServletConfig</code> object so that this |
| method can return it. The <a href="../../jakarta/servlet/GenericServlet.html" title="class in jakarta.servlet"><code>GenericServlet</code></a> class, which implements this interface, already does this.</div> |
| <dl> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>the <code>ServletConfig</code> object that initializes this servlet</dd> |
| <dt><span class="seeLabel">See Also:</span></dt> |
| <dd><a href="../../jakarta/servlet/Servlet.html#init-jakarta.servlet.ServletConfig-"><code>init(jakarta.servlet.ServletConfig)</code></a></dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="service-jakarta.servlet.ServletRequest-jakarta.servlet.ServletResponse-"> |
| <!-- --> |
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| <h4>service</h4> |
| <pre>void service(<a href="../../jakarta/servlet/ServletRequest.html" title="interface in jakarta.servlet">ServletRequest</a> req, |
| <a href="../../jakarta/servlet/ServletResponse.html" title="interface in jakarta.servlet">ServletResponse</a> res) |
| throws <a href="../../jakarta/servlet/ServletException.html" title="class in jakarta.servlet">ServletException</a>, |
| java.io.IOException</pre> |
| <div class="block">Called by the servlet container to allow the servlet to respond to a request. |
| |
| <p> |
| This method is only called after the servlet's <code>init()</code> method has completed successfully. |
| |
| <p> |
| The status code of the response always should be set for a servlet that throws or sends an error. |
| |
| |
| <p> |
| Servlets typically run inside multithreaded servlet containers that can handle multiple requests concurrently. |
| Developers must be aware to synchronize access to any shared resources such as files, network connections, and as |
| well as the servlet's class and instance variables.</div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>req</code> - the <code>ServletRequest</code> object that contains the client's request</dd> |
| <dd><code>res</code> - the <code>ServletResponse</code> object that contains the servlet's response</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code><a href="../../jakarta/servlet/ServletException.html" title="class in jakarta.servlet">ServletException</a></code> - if an exception occurs that interferes with the servlet's normal operation</dd> |
| <dd><code>java.io.IOException</code> - if an input or output exception occurs</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="getServletInfo--"> |
| <!-- --> |
| </a> |
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| <h4>getServletInfo</h4> |
| <pre>java.lang.String getServletInfo()</pre> |
| <div class="block">Returns information about the servlet, such as author, version, and copyright. |
| |
| <p> |
| The string that this method returns should be plain text and not markup of any kind (such as HTML, XML, etc.).</div> |
| <dl> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>a <code>String</code> containing servlet information</dd> |
| </dl> |
| </li> |
| </ul> |
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| <!-- --> |
| </a> |
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| <h4>destroy</h4> |
| <pre>void destroy()</pre> |
| <div class="block">Called by the servlet container to indicate to a servlet that the servlet is being taken out of service. This method |
| is only called once all threads within the servlet's <code>service</code> method have exited or after a timeout |
| period has passed. After the servlet container calls this method, it will not call the <code>service</code> method |
| again on this servlet. |
| |
| <p> |
| This method gives the servlet an opportunity to clean up any resources that are being held (for example, memory, file |
| handles, threads) and make sure that any persistent state is synchronized with the servlet's current state in memory.</div> |
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