pagecontext.html
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Java 2 Platform EE v1.3: Class PageContext
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javax.servlet.jsp</FONT>
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Class PageContext</H2>
<PRE>
java.lang.Object
|
+--<B>javax.servlet.jsp.PageContext</B>
</PRE>
<HR>
<DL>
<DT>public abstract class <B>PageContext</B><DT>extends java.lang.Object</DL>
<P>
<p>
A PageContext instance provides access to all the namespaces associated
with a JSP page, provides access to several page attributes, as well as
a layer above the implementation details. Implicit objects are added
the pageContext automatically.
<p> The <code> PageContext </code> class is an abstract class, designed to be
extended to provide implementation dependent implementations thereof, by
conformant JSP engine runtime environments. A PageContext instance is
obtained by a JSP implementation class by calling the
JspFactory.getPageContext() method, and is released by calling
JspFactory.releasePageContext().
<p> An example of how PageContext, JspFactory, and other classes can be
used within a JSP Page Implementation object is given elsewhere.
<p>
The PageContext provides a number of facilities to the page/component author and
page implementor, including:
<ul>
<li>a single API to manage the various scoped namespaces
<li>a number of convenience API's to access various public objects
<li>a mechanism to obtain the JspWriter for output
<li>a mechanism to manage session usage by the page
<li>a mechanism to expose page directive attributes to the scripting environment
<li>mechanisms to forward or include the current request to other active components in the application
<li>a mechanism to handle errorpage exception processing
</ul>
<p><B>Methods Intended for Container Generated Code</B>
<p>Some methods are intended to be used by the code generated by the
container, not by code written by JSP page authors, or JSP tag library authors.
<p>The methods supporting <B>lifecycle</B> are <code>initialize()</code>
and <code>release()</code>
<p>
The following methods enable the <B>management of nested</B> JspWriter streams to
implement Tag Extensions: <code>pushBody()</code> and <code>popBody()</code>
<p><B>Methods Intended for JSP authors</B>
<p>
Some methods provide <B>uniform access</B> to the diverse objects
representing scopes.
The implementation must use the underlying Servlet machinery
corresponding to that scope, so information can be passed back and
forth between Servlets and JSP pages. The methods are:
<code>setAttribute()</code>, <code>getAttribute()</code>,
<code>findAttribute()</code>, <code>removeAttribute()</code>,
<code>getAttributesScope()</code> and <code>getAttributeNamesInScope()</code> .
<p>
The following methods provide <B>convenient access</B> to implicit objects:
<ul>
<code>getOut()</code>, <code>getException()</code>, <code>getPage()</code>
<code>getRequest()</code>, <code>getResponse()</code>,
<code>getSession()</code>, <code>getServletConfig()</code>
and <code>getServletContext()</code>.
<p>
The following methods provide support for <B>forwarding, inclusion
and error handling</B>:
<code>forward()</code>, <code>include()</code>,
and <code>handlePageException()</code>.
<P>
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<CODE>static java.lang.String</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#APPLICATION">APPLICATION</A></B></CODE>
<BR>
Name used to store ServletContext in PageContext name table.</TD>
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<CODE>static int</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#APPLICATION_SCOPE">APPLICATION_SCOPE</A></B></CODE>
<BR>
Application scope: named reference remains available in the
ServletContext until it is reclaimed.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static java.lang.String</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#CONFIG">CONFIG</A></B></CODE>
<BR>
Name used to store ServletConfig in PageContext name table.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static java.lang.String</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#EXCEPTION">EXCEPTION</A></B></CODE>
<BR>
Name used to store uncaught exception in ServletRequest attribute list and PageContext name table.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static java.lang.String</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#OUT">OUT</A></B></CODE>
<BR>
Name used to store current JspWriter in PageContext name table.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static java.lang.String</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#PAGE">PAGE</A></B></CODE>
<BR>
Name used to store the Servlet in this PageContext's nametables.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static int</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#PAGE_SCOPE">PAGE_SCOPE</A></B></CODE>
<BR>
Page scope: (this is the default) the named reference remains available
in this PageContext until the return from the current Servlet.service()
invocation.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static java.lang.String</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#PAGECONTEXT">PAGECONTEXT</A></B></CODE>
<BR>
Name used to store this PageContext in it's own name table.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static java.lang.String</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#REQUEST">REQUEST</A></B></CODE>
<BR>
Name used to store ServletRequest in PageContext name table.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static int</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#REQUEST_SCOPE">REQUEST_SCOPE</A></B></CODE>
<BR>
Request scope: the named reference remains available from the ServletRequest
associated with the Servlet until the current request is completed.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static java.lang.String</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#RESPONSE">RESPONSE</A></B></CODE>
<BR>
Name used to store ServletResponse in PageContext name table.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static java.lang.String</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#SESSION">SESSION</A></B></CODE>
<BR>
Name used to store HttpSession in PageContext name table.</TD>
</TR>
<TR BGCOLOR="white" CLASS="TableRowColor">
<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
<CODE>static int</CODE></FONT></TD>
<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#SESSION_SCOPE">SESSION_SCOPE</A></B></CODE>
<BR>
Session scope (only valid if this page participates in a session):
the named reference remains available from the HttpSession (if any)
associated with the Servlet until the HttpSession is invalidated.</TD>
</TR>
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<TD><CODE><B><A HREF="../../../javax/servlet/jsp/PageContext.html#PageContext()">PageContext</A></B>()</CODE>
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