| java.lang.Object
 javax.el.ELContext
| ELContext | | abstract public class ELContext (Code) | | Context information for expression evaluation.
To evaluate an
Expression , an ELContext must be
provided. The ELContext holds:
- a reference to the base
ELResolver that will be consulted
to resolve model objects and their properties
- a reference to
FunctionMapper that will be used
to resolve EL Functions.
- a reference to
VariableMapper that will be used
to resolve EL Variables.
- a collection of all the relevant context objects for use by
ELResolvers
- state information during the evaluation of an expression, such as
whether a property has been resolved yet
The collection of context objects is necessary because each
ELResolver may need access to a different context object.
For example, JSP and Faces resolvers need access to a
javax.servlet.jsp.JspContext and a
javax.faces.context.FacesContext , respectively.
Creation of ELContext objects is controlled through
the underlying technology. For example, in JSP the
JspContext.getELContext() factory method is used.
Some technologies provide the ability to add an
ELContextListener so that applications and frameworks can ensure their own context objects
are attached to any newly created ELContext.
Because it stores state during expression evaluation, an
ELContext object is not thread-safe. Care should be taken
to never share an ELContext instance between two or more
threads.
See Also: ELContextListener
See Also: ELContextEvent
See Also: ELResolver
See Also: FunctionMapper
See Also: VariableMapper
See Also: javax.servlet.jsp.JspContext
since:
JSP 2.1 |
| Method Summary | |
| public Object | getContext(Class key)
Returns the context object associated with the given key.
The ELContext maintains a collection of context objects
relevant to the evaluation of an expression. | | abstract public ELResolver | getELResolver()
Retrieves the ELResolver associated with this context.
The ELContext maintains a reference to the
ELResolver that will be consulted to resolve variables
and properties during an expression evaluation. | | abstract public FunctionMapper | getFunctionMapper()
Retrieves the FunctionMapper associated with this
ELContext. | | public Locale | getLocale()
Get the Locale stored by a previous invocation to
ELContext.setLocale . | | abstract public VariableMapper | getVariableMapper()
Retrieves the VariableMapper associated with this
ELContext. | | public boolean | isPropertyResolved()
Returns whether an
ELResolver has successfully resolved a
given (base, property) pair. | | public void | putContext(Class key, Object contextObject)
Associates a context object with this ELContext.
The ELContext maintains a collection of context objects
relevant to the evaluation of an expression. | | public void | setLocale(Locale locale)
Set the Locale for this instance. | | public void | setPropertyResolved(boolean resolved)
Called to indicate that a ELResolver has successfully
resolved a given (base, property) pair. |
| getContext | | public Object getContext(Class key)(Code) | | Returns the context object associated with the given key.
The ELContext maintains a collection of context objects
relevant to the evaluation of an expression. These context objects
are used by ELResolvers. This method is used to
retrieve the context with the given key from the collection.
By convention, the object returned will be of the type specified by
the key. However, this is not required and the key is
used strictly as a unique identifier.
Parameters:
key - The unique identifier that was used to associate thecontext object with this ELContext. The context object associated with the given key, or nullif no such context was found.
throws:
NullPointerException - if key is null. |
| getELResolver | | abstract public ELResolver getELResolver()(Code) | | Retrieves the ELResolver associated with this context.
The ELContext maintains a reference to the
ELResolver that will be consulted to resolve variables
and properties during an expression evaluation. This method
retrieves the reference to the resolver.
Once an ELContext is constructed, the reference to the
ELResolver associated with the context cannot be changed.
The resolver to be consulted for variable andproperty resolution during expression evaluation. |
| getFunctionMapper | | abstract public FunctionMapper getFunctionMapper()(Code) | | Retrieves the FunctionMapper associated with this
ELContext.
The function mapper to be consulted for the resolution ofEL functions. |
| getLocale | | public Locale getLocale()(Code) | | Get the Locale stored by a previous invocation to
ELContext.setLocale . If this method returns non null,
this Locale must be used for all localization needs
in the implementation. The Locale must not be cached
to allow for applications that change Locale dynamically.
The Locale in which this instance is operating.Used primarily for message localization. |
| getVariableMapper | | abstract public VariableMapper getVariableMapper()(Code) | | Retrieves the VariableMapper associated with this
ELContext.
The variable mapper to be consulted for the resolution ofEL variables. |
| isPropertyResolved | | public boolean isPropertyResolved()(Code) | | Returns whether an
ELResolver has successfully resolved a
given (base, property) pair.
The
CompositeELResolver checks this property to determine
whether it should consider or skip other component resolvers.
See Also: CompositeELResolver true if the property has been resolved, or false if not. |
| putContext | | public void putContext(Class key, Object contextObject)(Code) | | Associates a context object with this ELContext.
The ELContext maintains a collection of context objects
relevant to the evaluation of an expression. These context objects
are used by ELResolvers. This method is used to
add a context object to that collection.
By convention, the contextObject will be of the
type specified by the key. However, this is not
required and the key is used strictly as a unique identifier.
Parameters:
key - The key used by an @{link ELResolver} to identify thiscontext object.
Parameters:
contextObject - The context object to add to the collection.
throws:
NullPointerException - if key is null or contextObject is null. |
| setLocale | | public void setLocale(Locale locale)(Code) | | Set the Locale for this instance. This method may be
called by the party creating the instance, such as JavaServer
Faces or JSP, to enable the EL implementation to provide localized
messages to the user. If no Locale is set, the implementation
must use the locale returned by Locale.getDefault( ).
|
| setPropertyResolved | | public void setPropertyResolved(boolean resolved)(Code) | | Called to indicate that a ELResolver has successfully
resolved a given (base, property) pair.
The
CompositeELResolver checks this property to determine
whether it should consider or skip other component resolvers.
See Also: CompositeELResolver
Parameters:
resolved - true if the property has been resolved, or false ifnot. |
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