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ResourceBundleELResolver (Java EE 5 SDK) - Java Platform, Enterprise Edition v5.0 API Specifications

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javax.el
Class ResourceBundleELResolver

java.lang.Object
  extended by javax.el.ELResolver
      extended by javax.el.ResourceBundleELResolver

public class ResourceBundleELResolver
extends ELResolver

Defines property resolution behavior on instances of ResourceBundle.

This resolver handles base objects of type java.util.ResourceBundle. It accepts any object as a property and coerces it to a java.lang.String for invoking ResourceBundle.getObject(java.lang.String).

This resolver is read only and will throw a PropertyNotWritableException if setValue is called.

ELResolvers are combined together using CompositeELResolvers, to define rich semantics for evaluating an expression. See the javadocs for ELResolver for details.

Since:
JSP 2.1
See Also:
CompositeELResolver, ELResolver, ResourceBundle

Field Summary
 
Fields inherited from class javax.el.ELResolver
RESOLVABLE_AT_DESIGN_TIME, TYPE
 
Constructor Summary
ResourceBundleELResolver()
           
 
Method Summary
 Class<?> getCommonPropertyType(ELContext context, Object base)
          If the base object is a ResourceBundle, returns the most general type that this resolver accepts for the property argument.
 Iterator getFeatureDescriptors(ELContext context, Object base)
          If the base object is a ResourceBundle, returns an Iterator containing the set of keys available in the ResourceBundle.
 Class<?> getType(ELContext context, Object base, Object property)
          If the base object is an instance of ResourceBundle, return null, since the resolver is read only.
 Object getValue(ELContext context, Object base, Object property)
          If the base object is an instance of ResourceBundle, the provided property will first be coerced to a String.
 boolean isReadOnly(ELContext context, Object base, Object property)
          If the base object is not null and an instanceof ResourceBundle, return true.
 void setValue(ELContext context, Object base, Object property, Object value)
          If the base object is a ResourceBundle, throw a PropertyNotWritableException.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ResourceBundleELResolver

public ResourceBundleELResolver()
Method Detail

getValue

public Object getValue(ELContext context,
                       Object base,
                       Object property)
If the base object is an instance of ResourceBundle, the provided property will first be coerced to a String. The Object returned by getObject on the base ResourceBundle will be returned.

If the base is ResourceBundle, 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.

Specified by:
getValue in class ELResolver
Parameters:
context - The context of this evaluation.
base - The ResourceBundle to analyze.
property - The name of the property to analyze. Will be coerced to a String.
Returns:
If the propertyResolved property of ELContext was set to true, then null if property is null; otherwise the Object for the given key (property coerced to String) from the ResourceBundle. If no object for the given key can be found, then the String "???" + key + "???".
Throws:
NullPointerException - if context is null
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.

getType

public Class<?> getType(ELContext context,
                        Object base,
                        Object property)
If the base object is an instance of ResourceBundle, return null, since the resolver is read only.

If the base is ResourceBundle, 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.

Specified by:
getType in class ELResolver
Parameters:
context - The context of this evaluation.
base - The ResourceBundle to analyze.
property - The name of the property to analyze.
Returns:
If the propertyResolved property of ELContext was set to true, then null; otherwise undefined.
Throws:
NullPointerException - if context is null

setValue

public void setValue(ELContext context,
                     Object base,
                     Object property,
                     Object value)
If the base object is a ResourceBundle, throw a PropertyNotWritableException.

Specified by:
setValue in class ELResolver
Parameters:
context - The context of this evaluation.
base - The ResourceBundle to be modified. Only bases that are of type ResourceBundle are handled.
property - The String property to use.
value - The value to be set.
Throws:
NullPointerException - if context is null.
PropertyNotWritableException - Always thrown if base is an instance of ReasourceBundle.

isReadOnly

public boolean isReadOnly(ELContext context,
                          Object base,
                          Object property)
If the base object is not null and an instanceof ResourceBundle, return true.

Specified by:
isReadOnly in class ELResolver
Parameters:
context - The context of this evaluation.
base - The ResourceBundle to be modified. Only bases that are of type ResourceBundle are handled.
property - The String property to use.
Returns:
If the propertyResolved property of ELContext was set to true, then true; otherwise undefined.
Throws:
NullPointerException - if context is null

getFeatureDescriptors

public Iterator getFeatureDescriptors(ELContext context,
                                      Object base)
If the base object is a ResourceBundle, returns an Iterator containing the set of keys available in the ResourceBundle. Otherwise, returns null.

The Iterator returned must contain zero or more instances of FeatureDescriptor. Each info object contains information about a key in the ResourceBundle, and is initialized as follows:

  • displayName - The String key
  • name - Same as displayName property.
  • shortDescription - Empty string
  • expert - false
  • hidden - false
  • preferred - true
    • In addition, the following named attributes must be set in the returned FeatureDescriptors:
  • ELResolver.TYPE - String.class
  • ELResolver.RESOLVABLE_AT_DESIGN_TIME - true

    • Specified by:
    getFeatureDescriptors in class ELResolver
    Parameters:
    context - The context of this evaluation.
    base - The bundle whose keys are to be iterated over. Only bases of type ResourceBundle are handled by this resolver.
    Returns:
    An Iterator containing zero or more (possibly infinitely more) FeatureDescriptor objects, each representing a key in this bundle, or null if the base object is not a ResourceBundle.
    See Also:
    FeatureDescriptor

    getCommonPropertyType

    public Class<?> getCommonPropertyType(ELContext context,
                                      Object base)
    If the base object is a ResourceBundle, returns the most general type that this resolver accepts for the property argument. Otherwise, returns null.

    Assuming the base is a ResourceBundle, this method will always return String.class.

    Specified by:
    getCommonPropertyType in class ELResolver
    Parameters:
    context - The context of this evaluation.
    base - The bundle to analyze. Only bases of type ResourceBundle are handled by this resolver.
    Returns:
    null if base is not a ResourceBundle; otherwise String.class.
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