public class CompositeELResolver extends ELResolver
getValue(ELContext, Object, Object)
,
getType(ELContext, Object, Object)
, setValue(ELContext, Object, Object, Object)
and isReadOnly(ELContext, Object, Object)
methods, an ELResolver is not responsible for
resolving all possible (base, property) pairs. In fact, most resolvers will only handle a base of a single type. To indicate that a resolver has successfully resolved a particular (base, property)
pair, it must set the propertyResolved property of the ELContext to true. If it could not handle the given pair, it must leave this property alone. The caller must ignore the return value of the
method if propertyResolved is false. The CompositeELResolver initializes the ELContext.propertyResolved flag to false, and uses it as a stop condition for iterating through its component resolvers.
The ELContext.propertyResolved flag is not used for the design-time methods getFeatureDescriptors(ELContext, Object)
and getCommonPropertyType(ELContext, Object)
. Instead, results
are collected and combined from all child ELResolvers for these methods.RESOLVABLE_AT_DESIGN_TIME, TYPE
Constructor and Description |
---|
CompositeELResolver() |
Modifier and Type | Method and Description |
---|---|
void |
add(ELResolver elResolver)
Adds the given resolver to the list of component resolvers.
|
Class<?> |
getCommonPropertyType(ELContext context,
Object base)
Returns the most general type that this resolver accepts for the property argument, given a base object.
|
Iterator<FeatureDescriptor> |
getFeatureDescriptors(ELContext context,
Object base)
Returns information about the set of variables or properties that can be resolved for the given base object.
|
Class<?> |
getType(ELContext context,
Object base,
Object property)
For a given base and property, attempts to identify the most general type that is acceptable for an object to be passed as the value parameter in a future call to the
setValue(ELContext, Object, Object, Object) method. |
Object |
getValue(ELContext context,
Object base,
Object property)
Attempts to resolve the given property object on the given base object by querying all component resolvers.
|
Object |
invoke(ELContext context,
Object base,
Object method,
Class<?>[] paramTypes,
Object[] params)
Attempts to resolve and invoke the given
method on the given base object by querying all component resolvers. |
boolean |
isReadOnly(ELContext context,
Object base,
Object property)
For a given base and property, attempts to determine whether a call to
setValue(ELContext, Object, Object, Object) will always fail. |
void |
setValue(ELContext context,
Object base,
Object property,
Object value)
Attempts to set the value of the given property object on the given base object.
|
public void add(ELResolver elResolver)
elResolver
- The component resolver to add.NullPointerException
- If the provided resolver is null.public Class<?> getCommonPropertyType(ELContext context, Object base)
getCommonPropertyType
in class ELResolver
context
- The context of this evaluation.base
- The base object to return the most general property type for, or null to enumerate the set of top-level variables that this resolver can evaluate.public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base)
getFeatureDescriptors
in class ELResolver
context
- The context of this evaluation.base
- The base object to return the most general property type for, or null to enumerate the set of top-level variables that this resolver can evaluate.public Class<?> getType(ELContext context, Object base, Object property)
setValue(ELContext, Object, Object, Object)
method. The result is obtained by querying all component resolvers. If this resolver handles the given (base, property) pair, 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. First, propertyResolved is set to false on the provided ELContext. Next, for each component resolver in this composite:
getType
in class ELResolver
context
- The context of this evaluation.base
- The base object to return the most general property type for, or null to enumerate the set of top-level variables that this resolver can evaluate.property
- The property or variable to return the acceptable type for.NullPointerException
- if context is nullPropertyNotFoundException
- 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)
getValue
in class ELResolver
context
- The context of this evaluation.base
- The base object to return the most general property type for, or null to enumerate the set of top-level variables that this resolver can evaluate.property
- The property or variable to return the acceptable type for.NullPointerException
- if context is nullPropertyNotFoundException
- 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 boolean isReadOnly(ELContext context, Object base, Object property)
setValue(ELContext, Object, Object, Object)
will always fail. The result is obtained by querying all component
resolvers. If this resolver handles the given (base, property) pair, 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. First, propertyResolved is set to false on the provided ELContext. Next, for each component resolver in this
composite:
isReadOnly
in class ELResolver
context
- The context of this evaluation.base
- The base object to return the most general property type for, or null to enumerate the set of top-level variables that this resolver can evaluate.property
- The property or variable to return the acceptable type for.NullPointerException
- if context is nullPropertyNotFoundException
- 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 value)
setValue
in class ELResolver
context
- The context of this evaluation.base
- The base object to return the most general property type for, or null to enumerate the set of top-level variables that this resolver can evaluate.property
- The property or variable to return the acceptable type for.value
- The value to set the property or variable to.NullPointerException
- if context is nullPropertyNotFoundException
- if base is not null and the specified property does not exist or is not readable.PropertyNotWritableException
- if the given (base, property) pair is handled by this ELResolver but the specified variable or property is not writable.ELException
- if an exception was thrown while attempting to set the property or variable. 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)
method
on the given base
object by querying all component resolvers.
If this resolver handles the given (base, method) pair, 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.
First, propertyResolved
is set to false
on the provided ELContext
.
Next, for each component resolver in this composite:
invoke()
method is called, passing in the provided context
, base
, method
, paramTypes
, and params
.ELContext
's propertyResolved
flag is false
then iteration continues.getValue()
is returned by this method.
If none of the component resolvers were able to perform this operation, the value null
is returned and the propertyResolved
flag remains set to false
Any exception thrown by component resolvers during the iteration is propagated to the caller of this method.
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 NoSuchMethodException is raised.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).Copyright © 2015 Alfresco. All rights reserved.