public class StaticFieldELResolver extends ELResolver
An ELResolver
for resolving static fields, enum constants and
static methods. Also handles constructor calls as a special case.
The resolver handles base objects of the type ELClass
, which
is usually generated by an EL implementation.
ELClass
RESOLVABLE_AT_DESIGN_TIME, TYPE
Constructor and Description |
---|
StaticFieldELResolver() |
Modifier and Type | Method and Description |
---|---|
Class<?> |
getCommonPropertyType(ELContext context,
Object base)
Returns the type of the property.
|
Iterator<FeatureDescriptor> |
getFeatureDescriptors(ELContext context,
Object base)
Returns the properties that can be resolved.
|
Class<?> |
getType(ELContext context,
Object base,
Object property)
Returns the type of a static field.
|
Object |
getValue(ELContext context,
Object base,
Object property)
Returns the value of a static field.
|
Object |
invoke(ELContext context,
Object base,
Object method,
Class<?>[] paramTypes,
Object[] params)
Invokes a public static method or the constructor for a class.
|
boolean |
isReadOnly(ELContext context,
Object base,
Object property)
Inquires whether the static field is writable.
|
void |
setValue(ELContext context,
Object base,
Object property,
Object value)
Attempts to write to a static field.
|
convertToType
public Object getValue(ELContext context, Object base, Object property)
Returns the value of a static field.
If the base object is an instance of ELClass
and the
property is String, 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.
ELClass
, return the value of the static field.
An Enum constant is a
public static field of an Enum object, and is a special case of this.getValue
in class ELResolver
context
- The context of this evaluation.base
- An ELClass
.property
- A static field name.propertyResolved
property of
ELContext
was set to true
, then
the static field value.NullPointerException
- if context is null
.PropertyNotFoundException
- if the specified class does not exist,
or if the field is not a public static filed of the class,
or if the field is inaccessible.public void setValue(ELContext context, Object base, Object property, Object value)
Attempts to write to a static field.
If the base object is an instance of ELClass
and the
property is String, a PropertyNotWritableException
will always be thrown, because writing to a static field is not
allowed.
setValue
in class ELResolver
context
- The context of this evaluation.base
- An ELClass
property
- The name of the fieldvalue
- The value to set the field of the class to.NullPointerException
- if context is null
PropertyNotWritableException
public Object invoke(ELContext context, Object base, Object method, Class<?>[] paramTypes, Object[] params)
Invokes a public static method or the constructor for a class.
If the base object is an instance ofELClass
and the
method is a String,
the propertyResolved
property of the
ELContext
object must be set to true
by the resolver, before returning. If this property is not
true
after this method is called, the caller
should ignore the return value.
Invoke the public static method specified by method
.
The process involved in the method selection is
the same as that used in BeanELResolver
.
As a special case, if the name of the method is "<init>", the constructor for the class will be invoked.
invoke
in class ELResolver
base
- An ELClass
method
- When coerced to a String
,
the simple name of the method.paramTypes
- An array of Class objects identifying the
method's formal parameter types, in declared order.
Use an empty array if the method has no parameters.
Can be null
, in which case the method's formal
parameter types are assumed to be unknown.params
- The parameters to pass to the method, or
null
if no parameters.context
- The context of this evaluation.null
if
the method has a void
return type).MethodNotFoundException
- if no suitable method can be found.ELException
- if an exception was thrown while performing
(base, method) resolution. The thrown exception must be
included as the cause property of this exception, if
available. If the exception thrown is an
InvocationTargetException
, extract its
cause
and pass it to the
ELException
constructor.public Class<?> getType(ELContext context, Object base, Object property)
Returns the type of a static field.
If the base object is an instance of ELClass
and the
property is a String,
the propertyResolved
property of the
ELContext
object must be set to true
by the resolver, before returning. If this property is not
true
after this method is called, the caller can
safely assume no value has been set.
getType
in class ELResolver
context
- The context of this evaluation.base
- An ELClass
.property
- The name of the field.propertyResolved
property of
ELContext
was set to true
, then
the type of the type of the field.NullPointerException
- if context is null
.PropertyNotFoundException
- if field is not a public static
filed of the class, or if the field is inaccessible.public boolean isReadOnly(ELContext context, Object base, Object property)
Inquires whether the static field is writable.
If the base object is an instance of ELClass
and the
property is a String,
the propertyResolved
property of the
ELContext
object must be set to true
by the resolver, before returning. If this property is not
true
after this method is called, the caller can
safely assume no value has been set.
Always returns a true
because writing to a static field
is not allowed.
isReadOnly
in class ELResolver
context
- The context of this evaluation.base
- An ELClass
.property
- The name of the bean.true
NullPointerException
- if context is null
.public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base)
null
, since there is no reason to
iterate through a list of one element: field name.getFeatureDescriptors
in class ELResolver
context
- The context of this evaluation.base
- An ELClass
.null
.FeatureDescriptor
public Class<?> getCommonPropertyType(ELContext context, Object base)
String.class
, since a field name is a String.getCommonPropertyType
in class ELResolver
context
- The context of this evaluation.base
- An ELClass
.String.class
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