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javax.servlet.jsp.el Class ScopedAttributeELResolver
java.lang.Object javax.el.ELResolver javax.servlet.jsp.el.ScopedAttributeELResolver
public class ScopedAttributeELResolver
- extends ELResolver
Defines variable resolution behavior for scoped attributes.
This resolver handles all variable resolutions (where base
is null
. It searches PageContext.findAttribute()
for a matching attribute. If not found, it will return null
,
or in the case of setValue
it will create a new attribute
in the page scope with the given name.
- Since:
- JSP 2.1
- See Also:
ELResolver
Field Summary |
---|
Fields inherited from class javax.el.ELResolver |
---|
RESOLVABLE_AT_DESIGN_TIME, TYPE |
Constructor Summary | |
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ScopedAttributeELResolver()
|
Method Summary | |
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Class<String> |
getCommonPropertyType(ELContext context,
Object base)
If the base object is null , returns
String.class . |
Iterator<FeatureDescriptor> |
getFeatureDescriptors(ELContext context,
Object base)
If the base object is null , returns an
Iterator containing FeatureDescriptor objects
with information about each scoped attribute resolved by this
resolver. |
Class<Object> |
getType(ELContext context,
Object base,
Object property)
If the base object is null , returns
Object.class to indicate that any type is valid to
set for a scoped attribute. |
Object |
getValue(ELContext context,
Object base,
Object property)
If the base object is null , searches the page,
request, session and application scopes for an attribute with
the given name and returns it, or null if no
attribute exists with the current name. |
boolean |
isReadOnly(ELContext context,
Object base,
Object property)
If the base object is null , returns false
to indicate that scoped attributes are never read-only. |
void |
setValue(ELContext context,
Object base,
Object property,
Object val)
If the base object is null , sets an existing scoped
attribute to the new value, or creates a new scoped attribute if one
does not exist by this name. |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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ScopedAttributeELResolver
public ScopedAttributeELResolver()
Method Detail |
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getValue
public Object getValue(ELContext context, Object base, Object property)
- If the base object is
null
, searches the page, request, session and application scopes for an attribute with the given name and returns it, ornull
if no attribute exists with the current name.The
propertyResolved
property of theELContext
object must be set totrue
by this resolver before returning if base isnull
. If this property is nottrue
after this method is called, the caller should ignore the return value. - Specified by:
getValue
in classELResolver
- Parameters:
context
- The context of this evaluation.base
- Onlynull
is handled by this resolver. Other values will result in an immediate return.property
- The name of the scoped attribute to resolve.- Returns:
- If the
propertyResolved
property ofELContext
was set totrue
, then the scoped attribute; otherwise undefined. - Throws:
NullPointerException
- if context isnull
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.
getType
public Class<Object> getType(ELContext context, Object base, Object property)
- If the base object is
null
, returnsObject.class
to indicate that any type is valid to set for a scoped attribute.The
propertyResolved
property of theELContext
object must be set totrue
by this resolver before returning if base isnull
. If this property is nottrue
after this method is called, the caller should ignore the return value. - Specified by:
getType
in classELResolver
- Parameters:
context
- The context of this evaluation.base
- Onlynull
is handled by this resolver. Other values will result in an immediate return.property
- The name of the scoped attribute to resolve.- Returns:
- If the
propertyResolved
property ofELContext
was set totrue
, thenObject.class
; otherwise undefined. - Throws:
NullPointerException
- if context isnull
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.
setValue
public void setValue(ELContext context, Object base, Object property, Object val)
- If the base object is
null
, sets an existing scoped attribute to the new value, or creates a new scoped attribute if one does not exist by this name.If the provided attribute name matches the key of an attribute in page scope, request scope, session scope, or application scope, the corresponding attribute value will be replaced by the provided value. Otherwise, a new page scope attribute will be created with the given name and value.
The
propertyResolved
property of theELContext
object must be set totrue
by this resolver before returning if base isnull
. If this property is nottrue
after this method is called, the caller should ignore the return value. - Specified by:
setValue
in classELResolver
- Parameters:
context
- The context of this evaluation.base
- Onlynull
is handled by this resolver. Other values will result in an immediate return.property
- The name of the scoped attribute to set.val
- The value for the scoped attribute.- Throws:
NullPointerException
- if context isnull
.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.
isReadOnly
public boolean isReadOnly(ELContext context, Object base, Object property)
- If the base object is
null
, returnsfalse
to indicate that scoped attributes are never read-only.The
propertyResolved
property of theELContext
object must be set totrue
by this resolver before returning if base isnull
. If this property is nottrue
after this method is called, the caller should ignore the return value. - Specified by:
isReadOnly
in classELResolver
- Parameters:
context
- The context of this evaluation.base
- Onlynull
is handled by this resolver. Other values will result in an immediate return.property
- The name of the scoped attribute.- Returns:
- If the
propertyResolved
property ofELContext
was set totrue
, thenfalse
; otherwise undefined. - Throws:
NullPointerException
- if context isnull
.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.
getFeatureDescriptors
public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base)
- If the base object is
null
, returns anIterator
containingFeatureDescriptor
objects with information about each scoped attribute resolved by this resolver. Otherwise, returnsnull
.The
Iterator
returned must contain one instance ofFeatureDescriptor
for each scoped attribute found in any scope. Each info object contains information about a single scoped attribute, and is initialized as follows:- displayName - The name of the scoped attribute.
- name - Same as displayName property.
- shortDescription - A suitable description for the scoped attribute. Should include the attribute's current scope (page, request, session, application). Will vary by implementation.
- expert -
false
- hidden -
false
- preferred -
true
FeatureDescriptor
s:
ELResolver.TYPE
- The current runtime type of the scoped attribute.ELResolver.RESOLVABLE_AT_DESIGN_TIME
- true
.
- Specified by:
getFeatureDescriptors
in classELResolver
- Parameters:
context
- The context of this evaluation.base
- Onlynull
is handled by this resolver. Other values will result in anull
return value.- Returns:
- An
Iterator
containing oneFeatureDescriptor
object for each scoped attribute, ornull
ifbase
is notnull
. - See Also:
FeatureDescriptor
getCommonPropertyType
public Class<String> getCommonPropertyType(ELContext context, Object base)
- If the base object is
null
, returnsString.class
. Otherwise, returnsnull
. - Specified by:
getCommonPropertyType
in classELResolver
- Parameters:
context
- The context of this evaluation.base
- Onlynull
is handled by this resolver. Other values will result in anull
return value.- Returns:
null
if base is notnull
; otherwiseString.class
.
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