javax.servlet.jsp.package.html Maven / Gradle / Ivy
Classes and interfaces for the Core JSP 2.1 API.
The javax.servlet.jsp package contains a number of classes and
interfaces that describe and define the contracts between a JSP page
implementation class and the runtime environment provided for an
instance of such a class by a conforming JSP container.
JSP Page Implementation Object Contract
This section describes the basic contract between a JSP Page
implementation object and its container.
The main contract is defined by the classes
{@link javax.servlet.jsp.JspPage}
and {@link javax.servlet.jsp.HttpJspPage}.
The {@link javax.servlet.jsp.JspFactory} class describes the mechanism to
portably instantiate all needed runtime objects,
and {@link javax.servlet.jsp.JspEngineInfo} provides basic information on
the current JSP container. Class {@link javax.servlet.jsp.JspApplicationContext}
stores application-scoped information relevant to JSP containers.
It was added in JSP 2.1 to support the integration of the unified
Expression Language.
None of these classes are intended to be used
by JSP page authors; an example of how these classes may be
used is included below.
Implicit Objects
The {@link javax.servlet.jsp.PageContext} object and the
{@link javax.servlet.jsp.JspWriter}
are available by default as implicit objects.
Exceptions
The {@link javax.servlet.jsp.JspException} class is the base class for all JSP
exceptions. The {@link javax.servlet.jsp.JspTagException} and
{@link javax.servlet.jsp.SkipPageException} exceptions are used by the
tag extension mechanism.
For JSP error pages, the {@link javax.servlet.jsp.ErrorData} class encapsulates information
about the error.
An Implementation Example
An instance of an implementation dependent subclass of the
{@link javax.servlet.jsp.PageContext}
abstract base class can be created by a JSP implementation class at
the beginning of it's _jspService() method via an
implementation default {@link javax.servlet.jsp.JspFactory}.
Here is one example of how to use these classes
public class foo implements Servlet {
// ...
public void _jspService(HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
JspFactory factory = JspFactory.getDefaultFactory();
PageContext pageContext = factory.getPageContext(
this,
request,
response,
null, // errorPageURL
false, // needsSession
JspWriter.DEFAULT_BUFFER,
true // autoFlush
);
// initialize implicit variables for scripting env ...
HttpSession session = pageContext.getSession();
JspWriter out = pageContext.getOut();
Object page = this;
try {
// body of translated JSP here ...
} catch (Exception e) {
out.clear();
pageContext.handlePageException(e);
} finally {
out.close();
factory.releasePageContext(pageContext);
}
}