Class 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
    • 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: jakarta.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: jakarta.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: jakarta.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: jakarta.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: jakarta.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: jakarta.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: jakarta.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: jakarta.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: jakarta.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: jakarta.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: jakarta.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.
      • 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: jakarta.servlet.jsp.PageContext
        The current value of the page object (In a Servlet environment, this is an instance of jakarta.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: jakarta.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: jakarta.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
      • forward

        public void forward​(String relativeUrlPath)
                     throws ServletException,
                            IOException
        Description copied from class: jakarta.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: jakarta.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: jakarta.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: jakarta.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: jakarta.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: jakarta.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