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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Frameset//EN""http://www.w3.org/TR/REC-html40/frameset.dtd"><!--NewPage--><HTML><HEAD><!-- Generated by javadoc on Fri Apr 04 16:56:25 PST 2003 --><TITLE>: Class HttpServlet</TITLE><LINK REL ="stylesheet" TYPE="text/css" HREF="../../../stylesheet.css" TITLE="Style"></HEAD><BODY BGCOLOR="white"><!-- ========== START OF NAVBAR ========== --><A NAME="navbar_top"><!-- --></A><TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0"><TR><TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"><A NAME="navbar_top_firstrow"><!-- --></A><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3"> <TR ALIGN="center" VALIGN="top"> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../overview-summary.html"><FONT ID="NavBarFont1"><B>Overview</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT ID="NavBarFont1"><B>Package</B></FONT></A> </TD> <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT ID="NavBarFont1"><B>Tree</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../deprecated-list.html"><FONT ID="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../index-all.html"><FONT ID="NavBarFont1"><B>Index</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../help-doc.html"><FONT ID="NavBarFont1"><B>Help</B></FONT></A> </TD> </TR></TABLE></TD><TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM></EM></TD></TR><TR><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../javax/servlet/http/Cookie.html"><B>PREV CLASS</B></A> <A HREF="../../../javax/servlet/http/HttpServletRequestWrapper.html"><B>NEXT CLASS</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../index.html" TARGET="_top"><B>FRAMES</B></A> <A HREF="HttpServlet.html" TARGET="_top"><B>NO FRAMES</B></A></FONT></TD></TR><TR><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: INNER | FIELD | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: FIELD | <A HREF="#constructor_detail">CONSTR</A> | <A HREF="#method_detail">METHOD</A></FONT></TD></TR></TABLE><!-- =========== END OF NAVBAR =========== --><HR><!-- ======== START OF CLASS DATA ======== --><H2><FONT SIZE="-1">javax.servlet.http</FONT><BR>Class HttpServlet</H2><PRE>java.lang.Object | +--<A HREF="../../../javax/servlet/GenericServlet.html">javax.servlet.GenericServlet</A> | +--<B>javax.servlet.http.HttpServlet</B></PRE><HR><DL><DT>public abstract class <B>HttpServlet</B><DT>extends <A HREF="../../../javax/servlet/GenericServlet.html">GenericServlet</A><DT>implements java.io.Serializable</DL><P>Provides an abstract class to be subclassed to create an HTTP servlet suitable for a Web site. A subclass of <code>HttpServlet</code> must override at least one method, usually one of these: <ul> <li> <code>doGet</code>, if the servlet supports HTTP GET requests <li> <code>doPost</code>, for HTTP POST requests <li> <code>doPut</code>, for HTTP PUT requests <li> <code>doDelete</code>, for HTTP DELETE requests <li> <code>init</code> and <code>destroy</code>, to manage resources that are held for the life of the servlet <li> <code>getServletInfo</code>, which the servlet uses to provide information about itself </ul> <p>There's almost no reason to override the <code>service</code> method. <code>service</code> handles standard HTTP requests by dispatching them to the handler methods for each HTTP request type (the <code>do</code><i>XXX</i> methods listed above). <p>Likewise, there's almost no reason to override the <code>doOptions</code> and <code>doTrace</code> methods. <p>Servlets typically run on multithreaded servers, so be aware that a servlet must handle concurrent requests and be careful to synchronize access to shared resources. Shared resources include in-memory data such as instance or class variables and external objects such as files, database connections, and network connections. See the <a href="http://java.sun.com/Series/Tutorial/java/threads/multithreaded.html"> Java Tutorial on Multithreaded Programming</a> for more information on handling multiple threads in a Java program.<P><DL><DT><B>See Also: </B><DD><A HREF="../../../serialized-form.html#javax.servlet.http.HttpServlet">Serialized Form</A></DL><HR><P><!-- ======== INNER CLASS SUMMARY ======== --><!-- =========== FIELD SUMMARY =========== --><!-- ======== CONSTRUCTOR SUMMARY ======== --><A NAME="constructor_summary"><!-- --></A><TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%"><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TD COLSPAN=2><FONT SIZE="+2"><B>Constructor Summary</B></FONT></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><B><A HREF="../../../javax/servlet/http/HttpServlet.html#HttpServlet()">HttpServlet</A></B>()</CODE><BR> Does nothing, because this is an abstract class.</TD></TR></TABLE> <!-- ========== METHOD SUMMARY =========== --><A NAME="method_summary"><!-- --></A><TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%"><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TD COLSPAN=2><FONT SIZE="+2"><B>Method Summary</B></FONT></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected void</CODE></FONT></TD><TD><CODE><B><A HREF="../../../javax/servlet/http/HttpServlet.html#doDelete(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)">doDelete</A></B>(<A HREF="../../../javax/servlet/http/HttpServletRequest.html">HttpServletRequest</A> req, <A HREF="../../../javax/servlet/http/HttpServletResponse.html">HttpServletResponse</A> resp)</CODE><BR> Called by the server (via the <code>service</code> method) to allow a servlet to handle a DELETE request.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected void</CODE></FONT></TD><TD><CODE><B><A HREF="../../../javax/servlet/http/HttpServlet.html#doGet(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)">doGet</A></B>(<A HREF="../../../javax/servlet/http/HttpServletRequest.html">HttpServletRequest</A> req, <A HREF="../../../javax/servlet/http/HttpServletResponse.html">HttpServletResponse</A> resp)</CODE><BR> Called by the server (via the <code>service</code> method) to allow a servlet to handle a GET request.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected void</CODE></FONT></TD><TD><CODE><B><A HREF="../../../javax/servlet/http/HttpServlet.html#doHead(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)">doHead</A></B>(<A HREF="../../../javax/servlet/http/HttpServletRequest.html">HttpServletRequest</A> req, <A HREF="../../../javax/servlet/http/HttpServletResponse.html">HttpServletResponse</A> resp)</CODE><BR> Receives an HTTP HEAD request from the protected <code>service</code> method and handles the request.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected void</CODE></FONT></TD><TD><CODE><B><A HREF="../../../javax/servlet/http/HttpServlet.html#doOptions(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)">doOptions</A></B>(<A HREF="../../../javax/servlet/http/HttpServletRequest.html">HttpServletRequest</A> req, <A HREF="../../../javax/servlet/http/HttpServletResponse.html">HttpServletResponse</A> resp)</CODE><BR> Called by the server (via the <code>service</code> method) to allow a servlet to handle a OPTIONS request.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected void</CODE></FONT></TD><TD><CODE><B><A HREF="../../../javax/servlet/http/HttpServlet.html#doPost(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)">doPost</A></B>(<A HREF="../../../javax/servlet/http/HttpServletRequest.html">HttpServletRequest</A> req, <A HREF="../../../javax/servlet/http/HttpServletResponse.html">HttpServletResponse</A> resp)</CODE><BR> Called by the server (via the <code>service</code> method) to allow a servlet to handle a POST request.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected void</CODE></FONT></TD><TD><CODE><B><A HREF="../../../javax/servlet/http/HttpServlet.html#doPut(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)">doPut</A></B>(<A HREF="../../../javax/servlet/http/HttpServletRequest.html">HttpServletRequest</A> req, <A HREF="../../../javax/servlet/http/HttpServletResponse.html">HttpServletResponse</A> resp)</CODE><BR> Called by the server (via the <code>service</code> method) to allow a servlet to handle a PUT request.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected void</CODE></FONT></TD><TD><CODE><B><A HREF="../../../javax/servlet/http/HttpServlet.html#doTrace(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)">doTrace</A></B>(<A HREF="../../../javax/servlet/http/HttpServletRequest.html">HttpServletRequest</A> req, <A HREF="../../../javax/servlet/http/HttpServletResponse.html">HttpServletResponse</A> resp)</CODE><BR> Called by the server (via the <code>service</code> method) to allow a servlet to handle a TRACE request.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected long</CODE></FONT></TD><TD><CODE><B><A HREF="../../../javax/servlet/http/HttpServlet.html#getLastModified(javax.servlet.http.HttpServletRequest)">getLastModified</A></B>(<A HREF="../../../javax/servlet/http/HttpServletRequest.html">HttpServletRequest</A> req)</CODE><BR> Returns the time the <code>HttpServletRequest</code> object was last modified, in milliseconds since midnight January 1, 1970 GMT.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE>protected void</CODE></FONT></TD><TD><CODE><B><A HREF="../../../javax/servlet/http/HttpServlet.html#service(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)">service</A></B>(<A HREF="../../../javax/servlet/http/HttpServletRequest.html">HttpServletRequest</A> req, <A HREF="../../../javax/servlet/http/HttpServletResponse.html">HttpServletResponse</A> resp)</CODE><BR> Receives standard HTTP requests from the public <code>service</code> method and dispatches them to the <code>do</code><i>XXX</i> methods defined in this class.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../../javax/servlet/http/HttpServlet.html#service(javax.servlet.ServletRequest, javax.servlet.ServletResponse)">service</A></B>(<A HREF="../../../javax/servlet/ServletRequest.html">ServletRequest</A> req, <A HREF="../../../javax/servlet/ServletResponse.html">ServletResponse</A> res)</CODE><BR> Dispatches client requests to the protected <code>service</code> method.</TD></TR></TABLE> <A NAME="methods_inherited_from_class_javax.servlet.GenericServlet"><!-- --></A><TABLE BORDER="1" CELLPADDING="3" CELLSPACING="0" WIDTH="100%"><TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor"><TD><B>Methods inherited from class javax.servlet.<A HREF="../../../javax/servlet/GenericServlet.html">GenericServlet</A></B></TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><A HREF="../../../javax/servlet/GenericServlet.html#destroy()">destroy</A>, <A HREF="../../../javax/servlet/GenericServlet.html#getInitParameter(java.lang.String)">getInitParameter</A>, <A HREF="../../../javax/servlet/GenericServlet.html#getInitParameterNames()">getInitParameterNames</A>, ⌨️ 快捷键说明
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