org.apache.jasper.runtime

Class PageContextImpl

java.lang.Object

javax.servlet.jsp.JspContext

javax.servlet.jsp.PageContext

org.apache.jasper.runtime.PageContextImpl

public class PageContextImpl
extends PageContext

Implementation of the PageContext class from the JSP spec. Also doubles as a VariableResolver for the EL.

Author:

Anil K. Vijendran, Larry Cable, Hans Bergsten, Pierre Delisle, Mark Roth, Jan Luehe, Jacob Hookom

Field Summary

Fields inherited from class javax.servlet.jsp.PageContext

APPLICATION, APPLICATION_SCOPE, CONFIG, EXCEPTION, OUT, PAGE, PAGE_SCOPE, PAGECONTEXT, REQUEST, REQUEST_SCOPE, RESPONSE, SESSION, SESSION_SCOPE

Method Summary

Modifier and Type	Method and Description
Object	findAttribute(String name) Searches for the named attribute in page, request, session (if valid), and application scope(s) in order and returns the value associated or null.
void	forward(String relativeUrlPath) This method is used to re-direct, or "forward" the current ServletRequest and ServletResponse to another active component in the application.
Object	getAttribute(String name) Returns the object associated with the name in the page scope or null if not found.
Object	getAttribute(String name, int scope) Return the object associated with the name in the specified scope or null if not found.
Enumeration<String>	getAttributeNamesInScope(int scope) Enumerate all the attributes in a given scope.
int	getAttributesScope(String name) Get the scope where a given attribute is defined.
ELContext	getELContext()
Exception	getException() Returns the exception associated with this page context, if any.
ExpressionEvaluator	getExpressionEvaluator() Deprecated.
JspWriter	getOut() The current value of the out object (a JspWriter).
Object	getPage() The current value of the page object (In a Servlet environment, this is an instance of javax.servlet.Servlet).
ServletRequest	getRequest() The current value of the request object (a ServletRequest).
ServletResponse	getResponse() The current value of the response object (a ServletResponse).
ServletConfig	getServletConfig() The ServletConfig instance.
ServletContext	getServletContext() The ServletContext instance.
HttpSession	getSession() The current value of the session object (an HttpSession).
VariableResolver	getVariableResolver() Deprecated.
void	handlePageException(Exception ex) This method is intended to process an unhandled 'page' level exception by forwarding the exception to the specified error page for this JSP.
void	handlePageException(Throwable t) This method is intended to process an unhandled 'page' level exception by forwarding the exception to the specified error page for this JSP.
void	include(String relativeUrlPath) Causes the resource specified to be processed as part of the current ServletRequest and ServletResponse being processed by the calling Thread.
void	include(String relativeUrlPath, boolean flush) Causes the resource specified to be processed as part of the current ServletRequest and ServletResponse being processed by the calling Thread.
void	initialize(Servlet servlet, ServletRequest request, ServletResponse response, String errorPageURL, boolean needsSession, int bufferSize, boolean autoFlush) The initialize method is called to initialize an uninitialized PageContext so that it may be used by a JSP Implementation class to service an incoming request and response within it's _jspService() method.
JspWriter	popBody() Return the previous JspWriter "out" saved by the matching pushBody(), and update the value of the "out" attribute in the page scope attribute namespace of the JspContext.
static Object	proprietaryEvaluate(String expression, Class<?> expectedType, PageContext pageContext, ProtectedFunctionMapper functionMap) Proprietary method to evaluate EL expressions.
BodyContent	pushBody() Return a new BodyContent object, save the current "out" JspWriter, and update the value of the "out" attribute in the page scope attribute namespace of the PageContext.
JspWriter	pushBody(Writer writer) Return a new JspWriter object that sends output to the provided Writer.
void	release() This method shall "reset" the internal state of a PageContext, releasing all internal references, and preparing the PageContext for potential reuse by a later invocation of initialize().
void	removeAttribute(String name) Remove the object reference associated with the given name from all scopes.
void	removeAttribute(String name, int scope) Remove the object reference associated with the specified name in the given scope.
void	setAttribute(String name, Object attribute) Register the name and value specified with page scope semantics.
void	setAttribute(String name, Object o, int scope) Register the name and value specified with appropriate scope semantics.

Methods inherited from class javax.servlet.jsp.PageContext

getErrorData

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

initialize

public void initialize(Servlet servlet,
                       ServletRequest request,
                       ServletResponse response,
                       String errorPageURL,
                       boolean needsSession,
                       int bufferSize,
                       boolean autoFlush)
                throws IOException

Description copied from class: javax.servlet.jsp.PageContext

The initialize method is called to initialize an uninitialized PageContext so that it may be used by a JSP Implementation class to service an incoming request and response within it's _jspService() method.

This method is typically called from JspFactory.getPageContext() in order to initialize state.

This method is required to create an initial JspWriter, and associate the "out" name in page scope with this newly created object.

This method should not be used by page or tag library authors.

Specified by:

initialize in class PageContext

Parameters:

servlet - The Servlet that is associated with this PageContext

request - The currently pending request for this Servlet

response - The currently pending response for this Servlet

errorPageURL - The value of the errorpage attribute from the page directive or null

needsSession - The value of the session attribute from the page directive

bufferSize - The value of the buffer attribute from the page directive

autoFlush - The value of the autoflush attribute from the page directive

Throws:

IOException - during creation of JspWriter

release

public void release()

Description copied from class: javax.servlet.jsp.PageContext

This method shall "reset" the internal state of a PageContext, releasing all internal references, and preparing the PageContext for potential reuse by a later invocation of initialize(). This method is typically called from JspFactory.releasePageContext().

Subclasses shall envelope this method.

This method should not be used by page or tag library authors.

Specified by:

release in class PageContext

getAttribute

public Object getAttribute(String name)

Description copied from class: javax.servlet.jsp.JspContext

Returns the object associated with the name in the page scope or null if not found.

Specified by:

getAttribute in class JspContext

Parameters:

name - the name of the attribute to get

Returns:

the object associated with the name in the page scope or null if not found.

getAttribute

public Object getAttribute(String name,
                           int scope)

Description copied from class: javax.servlet.jsp.JspContext

Return the object associated with the name in the specified scope or null if not found.

Specified by:

getAttribute in class JspContext

Parameters:

name - the name of the attribute to set

scope - the scope with which to associate the name/object

Returns:

the object associated with the name in the specified scope or null if not found.

setAttribute

public void setAttribute(String name,
                         Object attribute)

Description copied from class: javax.servlet.jsp.JspContext

Register the name and value specified with page scope semantics. If the value passed in is null, this has the same effect as calling removeAttribute( name, PageContext.PAGE_SCOPE ).

Specified by:

setAttribute in class JspContext

Parameters:

name - the name of the attribute to set

attribute - the value to associate with the name, or null if the attribute is to be removed from the page scope.

setAttribute

public void setAttribute(String name,
                         Object o,
                         int scope)

Description copied from class: javax.servlet.jsp.JspContext

Register the name and value specified with appropriate scope semantics. If the value passed in is null, this has the same effect as calling removeAttribute( name, scope ).

Specified by:

setAttribute in class JspContext

Parameters:

name - the name of the attribute to set

o - the object to associate with the name, or null if the attribute is to be removed from the specified scope.

scope - the scope with which to associate the name/object

removeAttribute

public void removeAttribute(String name,
                            int scope)

Description copied from class: javax.servlet.jsp.JspContext

Remove the object reference associated with the specified name in the given scope. Does nothing if there is no such object.

Specified by:

removeAttribute in class JspContext

Parameters:

name - The name of the object to remove.

scope - The scope where to look.

getAttributesScope

public int getAttributesScope(String name)

Description copied from class: javax.servlet.jsp.JspContext

Get the scope where a given attribute is defined.

Specified by:

getAttributesScope in class JspContext

Parameters:

name - the name of the attribute to return the scope for

Returns:

the scope of the object associated with the name specified or 0

findAttribute

public Object findAttribute(String name)

Description copied from class: javax.servlet.jsp.JspContext

Searches for the named attribute in page, request, session (if valid), and application scope(s) in order and returns the value associated or null.

Specified by:

findAttribute in class JspContext

Parameters:

name - the name of the attribute to search for

Returns:

the value associated or null

getAttributeNamesInScope

public Enumeration<String> getAttributeNamesInScope(int scope)

Description copied from class: javax.servlet.jsp.JspContext

Enumerate all the attributes in a given scope.

Specified by:

getAttributeNamesInScope in class JspContext

Parameters:

scope - the scope to enumerate all the attributes for

Returns:

an enumeration of names (java.lang.String) of all the attributes the specified scope

removeAttribute

public void removeAttribute(String name)

Description copied from class: javax.servlet.jsp.JspContext

Remove the object reference associated with the given name from all scopes. Does nothing if there is no such object.

Specified by:

removeAttribute in class JspContext

Parameters:

name - The name of the object to remove.

getOut

public JspWriter getOut()

Description copied from class: javax.servlet.jsp.JspContext

The current value of the out object (a JspWriter).

Specified by:

getOut in class JspContext

Returns:

the current JspWriter stream being used for client response

getSession

public HttpSession getSession()

Description copied from class: javax.servlet.jsp.PageContext

The current value of the session object (an HttpSession).

Specified by:

getSession in class PageContext

Returns:

the HttpSession for this PageContext or null

getServletConfig

public ServletConfig getServletConfig()

Description copied from class: javax.servlet.jsp.PageContext

The ServletConfig instance.

Specified by:

getServletConfig in class PageContext

Returns:

the ServletConfig for this PageContext

getServletContext

public ServletContext getServletContext()

Description copied from class: javax.servlet.jsp.PageContext

The ServletContext instance.

Specified by:

getServletContext in class PageContext

Returns:

the ServletContext for this PageContext

getRequest

public ServletRequest getRequest()

Description copied from class: javax.servlet.jsp.PageContext

The current value of the request object (a ServletRequest).

Specified by:

getRequest in class PageContext

Returns:

The ServletRequest for this PageContext

getResponse

public ServletResponse getResponse()

Description copied from class: javax.servlet.jsp.PageContext

The current value of the response object (a ServletResponse).

Specified by:

getResponse in class PageContext

Returns:

the ServletResponse for this PageContext

getException

public Exception getException()

Returns the exception associated with this page context, if any.

Added wrapping for Throwables to avoid ClassCastException: see Bugzilla 31171 for details.

Specified by:

getException in class PageContext

Returns:

The Exception associated with this page context, if any.

getPage

public Object getPage()

Description copied from class: javax.servlet.jsp.PageContext

The current value of the page object (In a Servlet environment, this is an instance of javax.servlet.Servlet).

Specified by:

getPage in class PageContext

Returns:

the Page implementation class instance associated with this PageContext

include

public void include(String relativeUrlPath)
             throws ServletException,
                    IOException

Description copied from class: javax.servlet.jsp.PageContext

Causes the resource specified to be processed as part of the current ServletRequest and ServletResponse being processed by the calling Thread. The output of the target resources processing of the request is written directly to the ServletResponse output stream.

The current JspWriter "out" for this JSP is flushed as a side-effect of this call, prior to processing the include.

If the relativeUrlPath begins with a "/" then the URL specified is calculated relative to the DOCROOT of the ServletContext for this JSP. If the path does not begin with a "/" then the URL specified is calculated relative to the URL of the request that was mapped to the calling JSP.

It is only valid to call this method from a Thread executing within a _jspService(...) method of a JSP.

Specified by:

include in class PageContext

Parameters:

relativeUrlPath - specifies the relative URL path to the target resource to be included

Throws:

ServletException - if the page that was forwarded to throws a ServletException

IOException - if an I/O error occurred while forwarding

include

public void include(String relativeUrlPath,
                    boolean flush)
             throws ServletException,
                    IOException

Description copied from class: javax.servlet.jsp.PageContext

Causes the resource specified to be processed as part of the current ServletRequest and ServletResponse being processed by the calling Thread. The output of the target resources processing of the request is written directly to the current JspWriter returned by a call to getOut().

If flush is true, The current JspWriter "out" for this JSP is flushed as a side-effect of this call, prior to processing the include. Otherwise, the JspWriter "out" is not flushed.

If the relativeUrlPath begins with a "/" then the URL specified is calculated relative to the DOCROOT of the ServletContext for this JSP. If the path does not begin with a "/" then the URL specified is calculated relative to the URL of the request that was mapped to the calling JSP.

It is only valid to call this method from a Thread executing within a _jspService(...) method of a JSP.

Specified by:

include in class PageContext

Parameters:

relativeUrlPath - specifies the relative URL path to the target resource to be included

flush - True if the JspWriter is to be flushed before the include, or false if not.

Throws:

ServletException - if the page that was forwarded to throws a ServletException

IOException - if an I/O error occurred while forwarding

getVariableResolver

@Deprecated
public VariableResolver getVariableResolver()

Deprecated.

Description copied from class: javax.servlet.jsp.JspContext

Returns an instance of a VariableResolver that provides access to the implicit objects specified in the JSP specification using this JspContext as the context object.

Specified by:

getVariableResolver in class JspContext

Returns:

A valid instance of a VariableResolver.

forward

public void forward(String relativeUrlPath)
             throws ServletException,
                    IOException

Description copied from class: javax.servlet.jsp.PageContext

This method is used to re-direct, or "forward" the current ServletRequest and ServletResponse to another active component in the application.

If the relativeUrlPath begins with a "/" then the URL specified is calculated relative to the DOCROOT of the ServletContext for this JSP. If the path does not begin with a "/" then the URL specified is calculated relative to the URL of the request that was mapped to the calling JSP.

It is only valid to call this method from a Thread executing within a _jspService(...) method of a JSP.

Once this method has been called successfully, it is illegal for the calling Thread to attempt to modify the ServletResponse object. Any such attempt to do so, shall result in undefined behavior. Typically, callers immediately return from _jspService(...) after calling this method.

Specified by:

forward in class PageContext

Parameters:

relativeUrlPath - specifies the relative URL path to the target resource as described above

Throws:

ServletException - if the page that was forwarded to throws a ServletException

IOException - if an I/O error occurred while forwarding

pushBody

public BodyContent pushBody()

Description copied from class: javax.servlet.jsp.PageContext

Return a new BodyContent object, save the current "out" JspWriter, and update the value of the "out" attribute in the page scope attribute namespace of the PageContext.

Overrides:

pushBody in class PageContext

Returns:

the new BodyContent

pushBody

public JspWriter pushBody(Writer writer)

Description copied from class: javax.servlet.jsp.JspContext

Return a new JspWriter object that sends output to the provided Writer. Saves the current "out" JspWriter, and updates the value of the "out" attribute in the page scope attribute namespace of the JspContext.

The returned JspWriter must implement all methods and behave as though it were unbuffered. More specifically:

• clear() must throw an IOException
• clearBuffer() does nothing
• getBufferSize() always returns 0
• getRemaining() always returns 0

Overrides:

pushBody in class JspContext

Parameters:

writer - The Writer for the returned JspWriter to send output to.

Returns:

a new JspWriter that writes to the given Writer.

popBody

public JspWriter popBody()

Description copied from class: javax.servlet.jsp.JspContext

Return the previous JspWriter "out" saved by the matching pushBody(), and update the value of the "out" attribute in the page scope attribute namespace of the JspContext.

Overrides:

popBody in class JspContext

Returns:

the saved JspWriter.

getExpressionEvaluator

@Deprecated
public ExpressionEvaluator getExpressionEvaluator()

Deprecated.

Provides programmatic access to the ExpressionEvaluator. The JSP Container must return a valid instance of an ExpressionEvaluator that can parse EL expressions.

Specified by:

getExpressionEvaluator in class JspContext

Returns:

A valid instance of an ExpressionEvaluator.

handlePageException

public void handlePageException(Exception ex)
                         throws IOException,
                                ServletException

Description copied from class: javax.servlet.jsp.PageContext

This method is intended to process an unhandled 'page' level exception by forwarding the exception to the specified error page for this JSP. If forwarding is not possible (for example because the response has already been committed), an implementation dependent mechanism should be used to invoke the error page (e.g. "including" the error page instead).

If no error page is defined in the page, the exception should be rethrown so that the standard servlet error handling takes over.

A JSP implementation class shall typically clean up any local state prior to invoking this and will return immediately thereafter. It is illegal to generate any output to the client, or to modify any ServletResponse state after invoking this call.

This method is kept for backwards compatibility reasons. Newly generated code should use PageContext.handlePageException(Throwable).

Specified by:

handlePageException in class PageContext

Parameters:

ex - the exception to be handled

Throws:

IOException - if an I/O error occurred while invoking the error page

ServletException - if an error occurs while invoking the error page

See Also:

PageContext.handlePageException(Throwable)

handlePageException

public void handlePageException(Throwable t)
                         throws IOException,
                                ServletException

Description copied from class: javax.servlet.jsp.PageContext

This method is intended to process an unhandled 'page' level exception by forwarding the exception to the specified error page for this JSP. If forwarding is not possible (for example because the response has already been committed), an implementation dependent mechanism should be used to invoke the error page (e.g. "including" the error page instead).

If no error page is defined in the page, the exception should be rethrown so that the standard servlet error handling takes over.

This method is intended to process an unhandled "page" level exception by redirecting the exception to either the specified error page for this JSP, or if none was specified, to perform some implementation dependent action.

A JSP implementation class shall typically clean up any local state prior to invoking this and will return immediately thereafter. It is illegal to generate any output to the client, or to modify any ServletResponse state after invoking this call.

Specified by:

handlePageException in class PageContext

Parameters:

t - the throwable to be handled

Throws:

IOException - if an I/O error occurred while invoking the error page

ServletException - if an error occurs while invoking the error page

See Also:

PageContext.handlePageException(Exception)

proprietaryEvaluate

public static Object proprietaryEvaluate(String expression,
                                         Class<?> expectedType,
                                         PageContext pageContext,
                                         ProtectedFunctionMapper functionMap)
                                  throws ELException

Proprietary method to evaluate EL expressions. XXX - This method should go away once the EL interpreter moves out of JSTL and into its own project. For now, this is necessary because the standard machinery is too slow.

Parameters:

expression - The expression to be evaluated

expectedType - The expected resulting type

pageContext - The page context

functionMap - Maps prefix and name to Method

Returns:

The result of the evaluation

Throws:

ELException - If an error occurs during the evaluation

getELContext

public ELContext getELContext()

Specified by:

getELContext in class JspContext