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.
ELResolvers are combined together using CompositeELResolvers, 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,
ELResolverRESOLVABLE_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 |
|---|---|
java.lang.Class<?> |
getCommonPropertyType(ELContext context,
java.lang.Object base)
If the base object is not
null, returns the most general type that this resolver accepts for the
property argument. |
java.util.Iterator<java.beans.FeatureDescriptor> |
getFeatureDescriptors(ELContext context,
java.lang.Object base)
If the base object is not
null, returns an Iterator containing the set of JavaBeans
properties available on the given object. |
java.lang.Class<?> |
getType(ELContext context,
java.lang.Object base,
java.lang.Object property)
If the base object is not
null, returns the most general acceptable type that can be set on this bean
property. |
java.lang.Object |
getValue(ELContext context,
java.lang.Object base,
java.lang.Object property)
If the base object is not
null, returns the current value of the given property on this bean. |
java.lang.Object |
invoke(ELContext context,
java.lang.Object base,
java.lang.Object methodName,
java.lang.Class<?>[] paramTypes,
java.lang.Object[] params)
If the base object is not
null, invoke the method, with the given parameters on this bean. |
boolean |
isReadOnly(ELContext context,
java.lang.Object base,
java.lang.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,
java.lang.Object base,
java.lang.Object property,
java.lang.Object val)
If the base object is not
null, attempts to set the value of the given property on this bean. |
convertToTypepublic 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 java.lang.Class<?> getType(ELContext context, java.lang.Object base, java.lang.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 ELResolvercontext - 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.java.lang.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 java.lang.Object getValue(ELContext context, java.lang.Object base, java.lang.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 ELResolvercontext - 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.java.lang.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, java.lang.Object base, java.lang.Object property, java.lang.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 ELResolvercontext - 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.java.lang.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 java.lang.Object invoke(ELContext context, java.lang.Object base, java.lang.Object methodName, java.lang.Class<?>[] paramTypes, java.lang.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 corresponding parameter types of the method, and the method is then
invoked.
invoke in class ELResolvercontext - The context of this evaluation.base - The bean on which to invoke the methodmethodName - 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, java.lang.Object base, java.lang.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 ELResolvercontext - 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.java.lang.NullPointerException - if context is nullPropertyNotFoundException - 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 java.util.Iterator<java.beans.FeatureDescriptor> getFeatureDescriptors(ELContext context, java.lang.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 ELResolvercontext - 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.FeatureDescriptorpublic java.lang.Class<?> getCommonPropertyType(ELContext context, java.lang.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 ELResolvercontext - The context of this evaluation.base - The bean to analyze.null if base is null; otherwise Object.class.