public class BeanELResolver extends ELResolver
This resolver handles base objects of any type, as long as the
base is not null
. It accepts any object as a property
or method, and coerces it to a string.
For property resolution, the property string is used to find a JavaBeans compliant property on the base object. The value is accessed using JavaBeans getters and setters.
For method resolution, the method string is the name of the method in the bean. The parameter types can be optionally specified to identify the method. If the parameter types are not specified, the parameter objects are used in the method resolution.
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
.
ELResolver
s are combined together using
CompositeELResolver
s, to define rich semantics for evaluating
an expression. See the javadocs for ELResolver
for details.
Because this resolver handles base objects of any type, it should be placed near the end of a composite resolver. Otherwise, it will claim to have resolved a property before any resolvers that come after it get a chance to test if they can do so as well.
CompositeELResolver
,
ELResolver
Modifier and Type | Class and Description |
---|---|
protected static class |
BeanELResolver.BeanProperties |
protected static class |
BeanELResolver.BeanProperty |
RESOLVABLE_AT_DESIGN_TIME, TYPE
Constructor and Description |
---|
BeanELResolver()
Creates a new read/write
BeanELResolver . |
BeanELResolver(boolean isReadOnly)
Creates a new
BeanELResolver whose read-only status is
determined by the given parameter. |
Modifier and Type | Method and Description |
---|---|
Class<?> |
getCommonPropertyType(ELContext context,
Object base)
If the base object is not
null , returns the most
general type that this resolver accepts for the
property argument. |
Iterator<FeatureDescriptor> |
getFeatureDescriptors(ELContext context,
Object base)
If the base object is not
null , returns an
Iterator containing the set of JavaBeans properties
available on the given object. |
Class<?> |
getType(ELContext context,
Object base,
Object property)
If the base object is not
null , returns the most
general acceptable type that can be set on this bean property. |
Object |
getValue(ELContext context,
Object base,
Object property)
If the base object is not
null , returns the current
value of the given property on this bean. |
Object |
invoke(ELContext context,
Object base,
Object method,
Class<?>[] paramTypes,
Object[] params)
If the base object is not
null , invoke the method, with
the given parameters on this bean. |
boolean |
isReadOnly(ELContext context,
Object base,
Object property)
If the base object is not
null , 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,
Object base,
Object property,
Object val)
If the base object is not
null , attempts to set the
value of the given property on this bean. |
public BeanELResolver()
BeanELResolver
.public BeanELResolver(boolean isReadOnly)
BeanELResolver
whose read-only status is
determined by the given parameter.isReadOnly
- true
if this resolver cannot modify
beans; false
otherwise.public Class<?> getType(ELContext context, Object base, Object property)
null
, returns the most
general acceptable type that can be set on this bean property.
If the base is not null
, 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.
The provided property will first be coerced to a String
.
If there is a BeanInfoProperty
for this property and
there were no errors retrieving it, the propertyType
of
the propertyDescriptor
is returned. Otherwise, a
PropertyNotFoundException
is thrown.
getType
in class ELResolver
context
- The context of this evaluation.base
- The bean to analyze.property
- The name of the property to analyze. Will be coerced to
a String
.propertyResolved
property of
ELContext
was set to true
, then
the most general acceptable type; otherwise undefined.NullPointerException
- if context is null
PropertyNotFoundException
- if base
is not
null
and the specified property does not exist
or is not readable.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 Object getValue(ELContext context, Object base, Object property)
null
, returns the current
value of the given property on this bean.
If the base is not null
, 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.
The provided property name will first be coerced to a
String
. If the property is a readable property of the
base object, as per the JavaBeans specification, then return the
result of the getter call. If the getter throws an exception,
it is propagated to the caller. If the property is not found or is
not readable, a PropertyNotFoundException
is thrown.
getValue
in class ELResolver
context
- The context of this evaluation.base
- The bean on which to get the property.property
- The name of the property to get. Will be coerced to
a String
.propertyResolved
property of
ELContext
was set to true
, then
the value of the given property. Otherwise, undefined.NullPointerException
- if context is null
.PropertyNotFoundException
- if base
is not
null
and the specified property does not exist
or is not readable.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, Object base, Object property, Object val)
null
, attempts to set the
value of the given property on this bean.
If the base is not null
, 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
.
The provided property name will first be coerced to a
String
. If property is a writable property of
base
(as per the JavaBeans Specification), the setter
method is called (passing value
). If the property exists
but does not have a setter, then a
PropertyNotFoundException
is thrown. If the property
does not exist, a PropertyNotFoundException
is thrown.
setValue
in class ELResolver
context
- The context of this evaluation.base
- The bean on which to set the property.property
- The name of the property to set. Will be coerced to
a String
.val
- The value to be associated with the specified key.NullPointerException
- if context is null
.PropertyNotFoundException
- if base
is not
null
and the specified property does not exist.PropertyNotWritableException
- if this resolver was constructed
in read-only mode, or if there is no setter for the property.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 Object invoke(ELContext context, Object base, Object method, Class<?>[] paramTypes, Object[] params)
null
, invoke the method, with
the given parameters on this bean. The return value from the method
is returned.
If the base is not null
, 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.
The provided method object will first be coerced to a
String
. The methods in the bean is then examined and
an attempt will be made to select one for invocation. If no suitable
can be found, a MethodNotFoundException
is thrown.
If the given paramTypes is not null
, select the method
with the given name and parameter types.
Else select the method with the given name that has the same number
of parameters. If there are more than one such method, the method
selection process is undefined.
Else select the method with the given name that takes a variable
number of arguments.
Note the resolution for overloaded methods will likely be clarified
in a future version of the spec.
The provide parameters are coerced to the correcponding parameter
types of the method, and the method is then invoked.
invoke
in class ELResolver
context
- The context of this evaluation.base
- The bean on which to invoke the methodmethod
- The simple name of the method to invoke.
Will be coerced to a String
. If method is
"<init>"or "<clinit>" a MethodNotFoundException is
thrown.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.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 boolean isReadOnly(ELContext context, Object base, Object property)
null
, returns whether a call
to setValue(javax.el.ELContext, java.lang.Object, java.lang.Object, java.lang.Object)
will always fail.
If the base is not null
, 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 return true
.
The provided property name will first be coerced to a
String
. If property is a writable property of
base
, false
is returned. If the property is
found but is not writable, true
is returned. If the
property is not found, a PropertyNotFoundException
is thrown.
isReadOnly
in class ELResolver
context
- The context of this evaluation.base
- The bean to analyze.property
- The name of the property to analyzed. Will be coerced to
a String
.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.NullPointerException
- if context is null
PropertyNotFoundException
- if base
is not
null
and the specified property does not exist.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 Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base)
null
, returns an
Iterator
containing the set of JavaBeans properties
available on the given object. Otherwise, returns null
.
The Iterator
returned must contain zero or more
instances of FeatureDescriptor
. Each info object
contains information about a property in the bean, as obtained by
calling the BeanInfo.getPropertyDescriptors
method.
The FeatureDescriptor
is initialized using the same
fields as are present in the PropertyDescriptor
,
with the additional required named attributes "type
" and
"resolvableAtDesignTime
" set as follows:
ELResolver.TYPE
- The runtime type of the property, from
PropertyDescriptor.getPropertyType()
.ELResolver.RESOLVABLE_AT_DESIGN_TIME
- true
.getFeatureDescriptors
in class ELResolver
context
- The context of this evaluation.base
- The bean to analyze.Iterator
containing zero or more
FeatureDescriptor
objects, each representing a property
on this bean, or null
if the base
object is null
.FeatureDescriptor
public Class<?> getCommonPropertyType(ELContext context, Object base)
null
, returns the most
general type that this resolver accepts for the
property
argument. Otherwise, returns null
.
Assuming the base is not null
, this method will always
return Object.class
. This is because any object is
accepted as a key and is coerced into a string.
getCommonPropertyType
in class ELResolver
context
- The context of this evaluation.base
- The bean to analyze.null
if base is null
; otherwise
Object.class
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