javax.el

Class BeanNameELResolver

Inhoudsopgave

  • public class BeanNameELResolver
extends ELResolver

    An ELResolver for resolving user or container managed beans.

    A BeanNameResolver is required for its proper operation. The following example creates an ELResolver that resolves the name "bean" to an instance of MyBean. 

     ELResovler elr = new BeanNameELResolver(new BeanNameResolver {
    public boolean isNameResolved(String beanName) {
       return "bean".equals(beanName);
    }
    public Object getBean(String beanName) {
       return "bean".equals(beanName)? new MyBean(): null;
    }
 });

    Since:
    EL 3.0

    • Constructor Detail

      • BeanNameELResolver

        public BeanNameELResolver(BeanNameResolver beanNameResolver)
        Constructor
        Parameters:
        beanNameResolver - The BeanNameResolver that resolves a bean name.

    • Method Detail

      • getValue

        public Object getValue(ELContext context,
                       Object base,
                       Object property)
        If the base object is null and the property is a name that is resolvable by the BeanNameResolver, returns the value resolved by the BeanNameResolver.

        If name is resolved by the BeanNameResolver, 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 - null
        property - The name of the bean.
        Returns:
        If the propertyResolved property of ELContext was set to true, then the value of the bean with the given name. Otherwise, undefined.
        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.

      • setValue

        public void setValue(ELContext context,
                     Object base,
                     Object property,
                     Object value)
        If the base is null and the property is a name that is resolvable by the BeanNameResolver, the bean in the BeanNameResolver is set to the given value.

        If the name is resolvable by the BeanNameResolver, or if the BeanNameResolver allows creating a new bean, 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 can safely assume no value has been set.

        Specified by:
        setValue in class ELResolver
        Parameters:
        context - The context of this evaluation.
        base - null
        property - The name of the bean
        value - The value to set the bean with the given name to.
        Throws:
        NullPointerException - if context is null
        PropertyNotWritableException - if the BeanNameResolver does not allow the bean to be modified.
        ELException - if an exception was thrown while attempting to set the bean with the given name. 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 is null and the property is a name resolvable by the BeanNameResolver, return the type of the bean.

        If the name is resolvable by the BeanNameResolver, 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 can safely assume no value has been set.

        Specified by:
        getType in class ELResolver
        Parameters:
        context - The context of this evaluation.
        base - null
        property - The name of the bean.
        Returns:
        If the propertyResolved property of ELContext was set to true, then the type of the bean with the given name. Otherwise, undefined.
        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.

      • isReadOnly

        public boolean isReadOnly(ELContext context,
                          Object base,
                          Object property)
        If the base is null and the property is a name resolvable by the BeanNameResolver, attempts to determine if the bean is writable.

        If the name is resolvable by the BeanNameResolver, 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 can safely assume no value has been set.

        Specified by:
        isReadOnly in class ELResolver
        Parameters:
        context - The context of this evaluation.
        base - null
        property - The name of the bean.
        Returns:
        If the propertyResolved property of ELContext was set to true, then true if the property is read-only or false if not; otherwise undefined.
        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.

      • getCommonPropertyType

        public Class<?> getCommonPropertyType(ELContext context,
                                      Object base)
        Always returns String.class, since a bean name is a String.
        Specified by:
        getCommonPropertyType in class ELResolver
        Parameters:
        context - The context of this evaluation.
        base - null.
        Returns:
        String.class.

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Document heeft de 11/06/2005 gemaakt, de laatste keer de 18/08/2025 gewijzigd
Bron van het afgedrukte document:https://www.gaudry.be/nl/java-api-javaee-rf-javax/el/beannameelresolver.html

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