|
DRAFT | ||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | ||||||||
java.lang.Objectjavax.el.ELResolver
javax.el.MapELResolver
public class MapELResolver
Defines property resolution behavior on instances of Map.
This resolver handles base objects of type java.util.Map.
It accepts any object as a property and uses that object as a key in
the map. The resulting value is the value in the map that is associated with
that key.
This resolver can be constructed in read-only mode, which means that
isReadOnly will always return true and
setValue(javax.el.ELContext, java.lang.Object, java.lang.Object, java.lang.Object) will always throw
PropertyNotWritableException.
ELResolvers are combined together using
CompositeELResolvers, to define rich semantics for evaluating
an expression. See the javadocs for ELResolver for details.
CompositeELResolver,
ELResolver,
Map| Field Summary |
|---|
| Fields inherited from class javax.el.ELResolver |
|---|
RESOLVABLE_AT_DESIGN_TIME, TYPE |
| Constructor Summary | |
|---|---|
MapELResolver()
Creates a new read/write MapELResolver. |
|
MapELResolver(boolean isReadOnly)
Creates a new MapELResolver whose read-only status is
determined by the given parameter. |
|
| Method Summary | |
|---|---|
java.lang.Class<?> |
getCommonPropertyType(ELContext context,
java.lang.Object base)
If the base object is a map, returns the most general type that this resolver accepts for the property argument. |
java.util.Iterator<java.beans.FeatureDescriptor> |
getFeatureDescriptors(ELContext context,
java.lang.Object base)
If the base object is a map, returns an Iterator
containing the set of keys available in the Map. |
java.lang.Class<?> |
getType(ELContext context,
java.lang.Object base,
java.lang.Object property)
If the base object is a map, returns the most general acceptable type for a value in this map. |
java.lang.Object |
getValue(ELContext context,
java.lang.Object base,
java.lang.Object property)
If the base object is a map, returns the value associated with the given key, as specified by the property argument. |
boolean |
isReadOnly(ELContext context,
java.lang.Object base,
java.lang.Object property)
If the base object is a map, returns whether a call to setValue(javax.el.ELContext, java.lang.Object, java.lang.Object, java.lang.Object) will always fail. |
void |
setValue(ELContext context,
java.lang.Object base,
java.lang.Object property,
java.lang.Object val)
If the base object is a map, attempts to set the value associated with the given key, as specified by the property argument. |
| Methods inherited from class javax.el.ELResolver |
|---|
invoke |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
|---|
public MapELResolver()
MapELResolver.
public MapELResolver(boolean isReadOnly)
MapELResolver whose read-only status is
determined by the given parameter.
isReadOnly - true if this resolver cannot modify
maps; false otherwise.| Method Detail |
|---|
public java.lang.Class<?> getType(ELContext context,
java.lang.Object base,
java.lang.Object property)
If the base is a Map, the propertyResolved
property of the ELContext object must be set to
true by this resolver, before returning. If this property
is not true after this method is called, the caller
should ignore the return value.
Assuming the base is a Map, this method will always
return Object.class. This is because Maps
accept any object as the value for a given key.
getType in class ELResolvercontext - The context of this evaluation.base - The map to analyze. Only bases of type Map
are handled by this resolver.property - The key to return the acceptable type for.
Ignored by this resolver.
propertyResolved property of
ELContext was set to true, then
the most general acceptable type; otherwise undefined.
java.lang.NullPointerException - if context is null
ELException - if an exception was thrown while performing
the property or variable resolution. The thrown exception
must be included as the cause property of this exception, if
available.
public java.lang.Object getValue(ELContext context,
java.lang.Object base,
java.lang.Object property)
property argument. If the
key was not found, null is returned.
If the base is a Map, the propertyResolved
property of the ELContext object must be set to
true by this resolver, before returning. If this property
is not true after this method is called, the caller
should ignore the return value.
Just as in Map.get(java.lang.Object), just because null
is returned doesn't mean there is no mapping for the key; it's also
possible that the Map explicitly maps the key to
null.
getValue in class ELResolvercontext - The context of this evaluation.base - The map to be analyzed. Only bases of type Map
are handled by this resolver.property - The key whose associated value is to be returned.
propertyResolved property of
ELContext was set to true, then
the value associated with the given key or null
if the key was not found. Otherwise, undefined.
java.lang.ClassCastException - if the key is of an inappropriate type
for this map (optionally thrown by the underlying Map).
java.lang.NullPointerException - if context is null, or if
the key is null and this map does not permit null keys (the
latter is optionally thrown by the underlying Map).
ELException - if an exception was thrown while performing
the property or variable resolution. The thrown exception
must be included as the cause property of this exception, if
available.
public void setValue(ELContext context,
java.lang.Object base,
java.lang.Object property,
java.lang.Object val)
property argument.
If the base is a Map, the propertyResolved
property of the ELContext object must be set to
true by this resolver, before returning. If this property
is not true after this method is called, the caller
can safely assume no value was set.
If this resolver was constructed in read-only mode, this method will
always throw PropertyNotWritableException.
If a Map was created using
Collections.unmodifiableMap(java.util.Map extends K, ? extends V>), this method must
throw PropertyNotWritableException. Unfortunately,
there is no Collections API method to detect this. However, an
implementation can create a prototype unmodifiable Map
and query its runtime type to see if it matches the runtime type of
the base object as a workaround.
setValue in class ELResolvercontext - The context of this evaluation.base - The map to be modified. Only bases of type Map
are handled by this resolver.property - The key with which the specified value is to be
associated.val - The value to be associated with the specified key.
java.lang.ClassCastException - if the class of the specified key or
value prevents it from being stored in this map.
java.lang.NullPointerException - if context is null, or if
this map does not permit null keys or values, and
the specified key or value is null.
java.lang.IllegalArgumentException - if some aspect of this key or
value prevents it from being stored in this map.
ELException - if an exception was thrown while performing
the property or variable resolution. The thrown exception
must be included as the cause property of this exception, if
available.
PropertyNotWritableException - if this resolver was constructed
in read-only mode, or if the put operation is not supported by
the underlying map.
public boolean isReadOnly(ELContext context,
java.lang.Object base,
java.lang.Object property)
setValue(javax.el.ELContext, java.lang.Object, java.lang.Object, java.lang.Object) will always fail.
If the base is a Map, the propertyResolved
property of the ELContext object must be set to
true by this resolver, before returning. If this property
is not true after this method is called, the caller
should ignore the return value.
If this resolver was constructed in read-only mode, this method will
always return true.
If a Map was created using
Collections.unmodifiableMap(java.util.Map extends K, ? extends V>), this method must
return true. Unfortunately, there is no Collections API
method to detect this. However, an implementation can create a
prototype unmodifiable Map and query its runtime type
to see if it matches the runtime type of the base object as a
workaround.
isReadOnly in class ELResolvercontext - The context of this evaluation.base - The map to analyze. Only bases of type Map
are handled by this resolver.property - The key to return the read-only status for.
Ignored by this resolver.
propertyResolved property of
ELContext was set to true, then
true if calling the setValue method
will always fail or false if it is possible that
such a call may succeed; otherwise undefined.
java.lang.NullPointerException - if context is null
ELException - if an exception was thrown while performing
the property or variable resolution. The thrown exception
must be included as the cause property of this exception, if
available.
public java.util.Iterator<java.beans.FeatureDescriptor> getFeatureDescriptors(ELContext context,
java.lang.Object base)
Iterator
containing the set of keys available in the Map.
Otherwise, returns null.
The Iterator returned must contain zero or more
instances of FeatureDescriptor. Each info object
contains information about a key in the Map, and is initialized as
follows:
toString method on this key, or
"null" if the key is null.falsefalsetrueFeatureDescriptors:
ELResolver#TYPE - The return value of calling the getClass()
method on this key, or null if the key is
null.ELResolver#RESOLVABLE_AT_DESIGN_TIME - true
getFeatureDescriptors in class ELResolvercontext - The context of this evaluation.base - The map whose keys are to be iterated over. Only bases
of type Map are handled by this resolver.
Iterator containing zero or more (possibly
infinitely more) FeatureDescriptor objects, each
representing a key in this map, or null if
the base object is not a map.FeatureDescriptor
public java.lang.Class<?> getCommonPropertyType(ELContext context,
java.lang.Object base)
property argument.
Otherwise, returns null.
Assuming the base is a Map, this method will always
return Object.class. This is because Maps
accept any object as a key.
getCommonPropertyType in class ELResolvercontext - The context of this evaluation.base - The map to analyze. Only bases of type Map
are handled by this resolver.
null if base is not a Map; otherwise
Object.class.
|
DRAFT | ||||||||
| PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
| SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD | ||||||||
Copyright © 2009 Sun Microsystems, Inc. All Rights Reserved. Use is subject to license terms.
Generated on 24-November-2009 03:24