Package javax.el

Class ELResolver

java.lang.Object

javax.el.ELResolver

Direct Known Subclasses:

ArrayELResolver, BeanELResolver, BeanNameELResolver, CompositeELResolver, ELResolverImpl, ImplicitObjectELResolver, JasperELResolver.GraalBeanELResolver, ListELResolver, MapELResolver, ResourceBundleELResolver, ScopedAttributeELResolver, StaticFieldELResolver, StreamELResolverImpl, TypeConverter

public abstract class ELResolver
extends Object

Author:

Jacob Hookom [jacob/hookom.net]

Field Summary

Fields

Modifier and Type	Field	Description
static String	RESOLVABLE_AT_DESIGN_TIME
static String	TYPE

Constructor Summary

Constructors

Constructor	Description
ELResolver()

Method Summary

Modifier and Type	Method	Description
Object	convertToType(ELContext context, Object obj, Class<?> type)	Converts the given object to the given type.
abstract Class<?>	getCommonPropertyType(ELContext context, Object base)	Obtain the most common type that is acceptable for the given base object.
abstract Iterator<FeatureDescriptor>	getFeatureDescriptors(ELContext context, Object base)	Obtain the feature descriptors for the resolvable properties of the given object.
abstract Class<?>	getType(ELContext context, Object base, Object property)	Obtain the most generally acceptable type that may be used to set the given property on the given object using the given context.
abstract Object	getValue(ELContext context, Object base, Object property)	Obtain the value of the given property on the given object using the given context.
Object	invoke(ELContext context, Object base, Object method, Class<?>[] paramTypes, Object[] params)	Invokes a method on the the given object.
abstract boolean	isReadOnly(ELContext context, Object base, Object property)	Determine if the given property on the given object is read-only using the given context.
abstract void	setValue(ELContext context, Object base, Object property, Object value)	Set the value of the given property on the given object using the given context.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

TYPE

public static final String TYPE

See Also:

Constant Field Values

RESOLVABLE_AT_DESIGN_TIME

public static final String RESOLVABLE_AT_DESIGN_TIME

See Also:

Constant Field Values

Constructor Detail

ELResolver

public ELResolver()

Method Detail

getValue

public abstract Object getValue(ELContext context,
                                Object base,
                                Object property)

Obtain the value of the given property on the given object using the given context.

Parameters:

context - The EL context for this evaluation

base - The base object on which the property is to be found

property - The property whose value is to be returned

Returns:

the value of the provided property

Throws:

NullPointerException - If the supplied context is null

PropertyNotFoundException - If the base/property combination provided to the resolver is one that the resolver can handle but no match was found or a match was found but was not readable

ELException - Wraps any exception throw whilst resolving the property

invoke

public Object invoke(ELContext context,
                     Object base,
                     Object method,
                     Class<?>[] paramTypes,
                     Object[] params)

Invokes a method on the the given object. This default implementation always returns null.

Parameters:

context - The EL context for this evaluation

base - The base object on which the method is to be found

method - The method to invoke

paramTypes - The types of the parameters of the method to invoke

params - The parameters with which to invoke the method

Returns:

Always null

Since:

EL 2.2

getType

public abstract Class<?> getType(ELContext context,
                                 Object base,
                                 Object property)

Obtain the most generally acceptable type that may be used to set the given property on the given object using the given context.

Parameters:

context - The EL context for this evaluation

base - The base object on which the property is to be found

property - The property whose type is to be returned

Returns:

the most general type that maybe used to set the provided property or null if the resolver is read-only.

Throws:

NullPointerException - If the supplied context is null

PropertyNotFoundException - If the base/property combination provided to the resolver is one that the resolver can handle but no match was found or a match was found but was not readable

ELException - Wraps any exception throw whilst resolving the property

setValue

public abstract void setValue(ELContext context,
                              Object base,
                              Object property,
                              Object value)

Set the value of the given property on the given object using the given context.

Parameters:

context - The EL context for this evaluation

base - The base object on which the property is to be found

property - The property whose value is to be set

value - The value to set the property to

Throws:

NullPointerException - If the supplied context is null

PropertyNotFoundException - If the base/property combination provided to the resolver is one that the resolver can handle but no match was found

PropertyNotWritableException - If the base/property combination provided to the resolver is one that the resolver can handle but the property was not writable

ELException - Wraps any exception throw whilst resolving the property

isReadOnly

public abstract boolean isReadOnly(ELContext context,
                                   Object base,
                                   Object property)

Determine if the given property on the given object is read-only using the given context.

Parameters:

context - The EL context for this evaluation

base - The base object on which the property is to be found

property - The property to be checked for read only status

Returns:

true if the identified property is read only, otherwise false

Throws:

NullPointerException - If the supplied context is null

PropertyNotFoundException - If the base/property combination provided to the resolver is one that the resolver can handle but no match was found

ELException - Wraps any exception throw whilst resolving the property

getFeatureDescriptors

public abstract Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context,
                                                                  Object base)

Obtain the feature descriptors for the resolvable properties of the given object.

Parameters:

context - The context in which the examination takes place

base - The object to examine

Returns:

An iterator, possibly empty, of feature descriptors of the given object

getCommonPropertyType

public abstract Class<?> getCommonPropertyType(ELContext context,
                                               Object base)

Obtain the most common type that is acceptable for the given base object.

Parameters:

context - The context in which the examination takes place

base - The object to examine

Returns:

{code null} if the most common type cannot be determine, otherwise the most common type

convertToType

public Object convertToType(ELContext context,
                            Object obj,
                            Class<?> type)

Converts the given object to the given type. This default implementation always returns null.

Parameters:

context - The EL context for this evaluation

obj - The object to convert

type - The type to which the object should be converted

Returns:

Always null

Since:

EL 3.0