PageContextImpl (Apache Tomcat 7.0.109 API Documentation)

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

Methods
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, boolean escape)` 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: PageContext
    
    The ServletConfig instance.
    
    Specified by:
    
    getServletConfig in class PageContext
    
    Returns:
    the ServletConfig for this PageContext
  - getServletContext
```
public ServletContext getServletContext()
```
    Description copied from class: PageContext
    
    The ServletContext instance.
    
    Specified by:
    
    getServletContext in class PageContext
    
    Returns:
    the ServletContext for this PageContext
  - getRequest
```
public ServletRequest getRequest()
```
    Description copied from class: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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: 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,
                         boolean escape)
                                  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
    escape - Unused
    
    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

Class PageContextImpl

Field Summary

Fields inherited from class javax.servlet.jsp.PageContext

Method Summary

Methods inherited from class javax.servlet.jsp.PageContext

Methods inherited from class java.lang.Object

Method Detail

initialize

release

getAttribute

getAttribute

setAttribute

setAttribute

removeAttribute

getAttributesScope

findAttribute

getAttributeNamesInScope

removeAttribute

getOut

getSession

getServletConfig

getServletContext

getRequest

getResponse

getException

getPage

include

include

getVariableResolver

forward

pushBody

pushBody

popBody

getExpressionEvaluator

handlePageException

handlePageException

proprietaryEvaluate

getELContext