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java.lang.Objectorg.jdesktop.el.ELContext
public abstract class ELContext
Context information for expression evaluation.
To evaluate an Expression, an ELContext must be
provided. The ELContext holds:
ELResolver that will be consulted
to resolve model objects and their propertiesFunctionMapper that will be used
to resolve EL Functions.
VariableMapper that will be used
to resolve EL Variables.
ELResolversThe 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.
ELContextListener,
ELContextEvent,
ELResolver,
FunctionMapper,
VariableMapper,
javax.servlet.jsp.JspContext| Field Summary | |
|---|---|
static java.lang.Object |
UNRESOLVABLE_RESULT
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| Constructor Summary | |
|---|---|
ELContext()
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| Method Summary | |
|---|---|
java.lang.Object |
getContext(java.lang.Class key)
Returns the context object associated with the given key. |
abstract ELResolver |
getELResolver()
Retrieves the ELResolver associated with this context. |
abstract FunctionMapper |
getFunctionMapper()
Retrieves the FunctionMapper associated with this
ELContext. |
java.util.Locale |
getLocale()
Get the Locale stored by a previous invocation to
setLocale(java.util.Locale). |
abstract VariableMapper |
getVariableMapper()
Retrieves the VariableMapper associated with this
ELContext. |
boolean |
isPropertyResolved()
Returns whether an ELResolver has successfully resolved a
given (base, property) pair. |
void |
putContext(java.lang.Class key,
java.lang.Object contextObject)
Associates a context object with this ELContext. |
void |
setLocale(java.util.Locale locale)
Set the Locale for this instance. |
void |
setPropertyResolved(boolean resolved)
Called to indicate that a ELResolver has successfully
resolved a given (base, property) pair. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Field Detail |
|---|
public static final java.lang.Object UNRESOLVABLE_RESULT
| Constructor Detail |
|---|
public ELContext()
| Method Detail |
|---|
public void setPropertyResolved(boolean resolved)
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.
resolved - true if the property has been resolved, or false if
not.CompositeELResolverpublic boolean isPropertyResolved()
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.
CompositeELResolver
public void putContext(java.lang.Class key,
java.lang.Object contextObject)
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.
key - The key used by an @{link ELResolver} to identify this
context object.contextObject - The context object to add to the collection.
java.lang.NullPointerException - if key is null or contextObject is null.public java.lang.Object getContext(java.lang.Class 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.
key - The unique identifier that was used to associate the
context object with this ELContext.
java.lang.NullPointerException - if key is null.public abstract ELResolver getELResolver()
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.
public abstract FunctionMapper getFunctionMapper()
FunctionMapper associated with this
ELContext.
public java.util.Locale getLocale()
Locale stored by a previous invocation to
setLocale(java.util.Locale). 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.
Locale in which this instance is operating.
Used primarily for message localization.public void setLocale(java.util.Locale locale)
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( ).
public abstract VariableMapper getVariableMapper()
VariableMapper associated with this
ELContext.
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