Interface | Description |
---|---|
HttpJspPage |
The HttpJspPage interface describes the interaction that a JSP Page
Implementation Class must satisfy when using the HTTP protocol.
|
JspApplicationContext |
Stores application-scoped information relevant to JSP containers.
|
JspPage |
The JspPage interface describes the generic interaction that a JSP Page
Implementation class must satisfy; pages that use the HTTP protocol
are described by the HttpJspPage interface.
|
Class | Description |
---|---|
ErrorData |
Contains information about an error, for error pages.
|
JspContext |
JspContext serves as the base class for the
PageContext class and abstracts all information that is not specific
to servlets. |
JspEngineInfo |
The JspEngineInfo is an abstract class that provides information on the
current JSP engine.
|
JspFactory |
The JspFactory is an abstract class that defines a number of factory
methods available to a JSP page at runtime for the purposes of creating
instances of various interfaces and classes used to support the JSP
implementation.
|
JspWriter |
The actions and template data in a JSP page is written using the
JspWriter object that is referenced by the implicit variable out which
is initialized automatically using methods in the PageContext object.
|
PageContext |
PageContext extends JspContext to provide useful context information for
when JSP technology is used in a Servlet environment.
|
Exception | Description |
---|---|
JspException |
A generic exception known to the JSP engine; uncaught
JspExceptions will result in an invocation of the errorpage
machinery.
|
JspTagException |
Exception to be used by a Tag Handler to indicate some unrecoverable
error.
|
SkipPageException |
Exception to indicate the calling page must cease evaluation.
|
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.
This section describes the basic contract between a JSP Page implementation object and its container.
The main contract is defined by the classes
JspPage
and HttpJspPage
.
The JspFactory
class describes the mechanism to
portably instantiate all needed runtime objects,
and JspEngineInfo
provides basic information on
the current JSP container. Class 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.
PageContext
object and the
JspWriter
are available by default as implicit objects.
The JspException
class is the base class for all JSP
exceptions. The JspTagException
and
SkipPageException
exceptions are used by the
tag extension mechanism.
ErrorData
class encapsulates information
about the error.
An instance of an implementation dependent subclass of the
PageContext
abstract base class can be created by a JSP implementation class at
the beginning of it's _jspService()
method via an
implementation default 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);
}
}
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