Package de.xima.fc.gui.util

Class ComponentAttribute<T>

java.lang.Object

de.xima.fc.gui.util.ComponentAttribute<T>

Type Parameters:

T - The expected type of the attribute value.

public final class ComponentAttribute<T>
extends Object

Helper class reading and writing attributes of a Faces UIComponent.

This class encapsulates the logic for accessing attributes of components, whether they are defined as literal attributes or as value expressions. Intended to be used as part of component implementations, especially for composite components.

Since:

8.5.4

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ComponentAttribute.Builder<T>	Builder for creating instances of ComponentAttribute with a fluent API for configuration.

Method Summary

Modifier and Type	Method	Description
javax.el.MethodExpression	asMethodExpression(Class<?> returnType, Class<?>... paramTypes)	Gets the attribute as a method expression with the specified return type and parameter types.
javax.el.ValueExpression	asValueExpression()	Gets the attribute as a value expression.
static <T> ComponentAttribute.Builder<T>	builder(javax.faces.component.UIComponent component, String attributeName, Class<T> type)	Creates a builder for a component attribute with the specified name and expected type.
static <T> ComponentAttribute.Builder<List<T>>	builderForList(javax.faces.component.UIComponent component, String attributeName, Class<T> type)	Creates a builder for a component attribute that is expected to be a list of a specific type.
javax.el.ValueExpression	convertToValueExpression()	Converts the attribute to a value expression.
T	get()	Retrieves the current value of the attribute.
<R> R	invoke(Class<R> returnType, Class<?>[] paramTypes, Object... params)	Invokes the method defined by this attribute as a method expression with the specified return type and parameter types, using the provided parameters.
void	set(T value)	Updates the attribute value and synchronizes it with the underlying data model.

Methods inherited from class java.lang.Object

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

Method Detail

asMethodExpression

public javax.el.MethodExpression asMethodExpression(Class<?> returnType,
                                                    Class<?>... paramTypes)

Gets the attribute as a method expression with the specified return type and parameter types. If the attribute does not define a method expression, returns null.

Parameters:

returnType - The expected return type of the method expression

paramTypes - The expected parameter types of the method expression

Returns:

The method expression if defined and compatible, or null otherwise.

asValueExpression

public javax.el.ValueExpression asValueExpression()

Gets the attribute as a value expression. If the attribute does not define a value expression, returns null.

Returns:

The value expression if defined, or null otherwise.

convertToValueExpression

public javax.el.ValueExpression convertToValueExpression()

Converts the attribute to a value expression. If the attribute is defined as a literal attribute, it is wrapped in a literal value expression. If the attribute is not defined at all, returns null.

Returns:

The value expression representing the attribute, or null if the attribute is not defined.

get

public T get()

Retrieves the current value of the attribute.

The value is dynamically resolved during each call to ensure synchronization with the current JSF context and component state.

Returns:

The resolved value of type T.

Throws:

javax.el.PropertyNotFoundException - If the property is missing or null, and either throwOnMissingValue or throwOnNullValue is enabled.

IllegalArgumentException - if the resolved value is null or of an incompatible type.

invoke

public <R> R invoke(Class<R> returnType,
                    Class<?>[] paramTypes,
                    Object... params)

Invokes the method defined by this attribute as a method expression with the specified return type and parameter types, using the provided parameters.

Type Parameters:

R - The expected return type of the method expression.

Parameters:

returnType - The expected return type of the method expression

paramTypes - The expected parameter types of the method expression

params - The parameters to pass to the method expression when invoking it.

Returns:

The result of the method expression invocation, cast to the specified return type.

Throws:

javax.el.MethodNotFoundException - If no compatible method expression is found for the attribute with the specified return type and parameter types.

set

public void set(T value)

Updates the attribute value and synchronizes it with the underlying data model.

If a ValueExpression is associated with this attribute, the method attempts to update the source bean directly. If no expression is found, the value is stored in the component's local attribute map, and a warning is logged.

Parameters:

value - The new value to set.

Throws:

javax.el.PropertyNotWritableException - If the property is not writable and throwOnNonWritableProperty is enabled.

builder

public static <T> ComponentAttribute.Builder<T> builder(javax.faces.component.UIComponent component,
                                                        String attributeName,
                                                        Class<T> type)

Creates a builder for a component attribute with the specified name and expected type. The builder allows configuring various options for how the attribute is accessed and manipulated, such as initial value suppliers and error handling behavior.

Type Parameters:

T - The expected type of the attribute value.

Parameters:

component - The component for which to create the attribute builder.

attributeName - The name of the attribute to access on the component.

type - The expected type of the attribute value, used for type checking and casting.

Returns:

A builder for creating a ComponentAttribute instance with the specified configuration.

builderForList

public static <T> ComponentAttribute.Builder<List<T>> builderForList(javax.faces.component.UIComponent component,
                                                                     String attributeName,
                                                                     Class<T> type)

Creates a builder for a component attribute that is expected to be a list of a specific type. This is a convenience method since Java does not allow class literals for parameterized types (e.g. List<String>.class is not valid).

Type Parameters:

T - The expected type of the attribute value.

Parameters:

component - The component for which to create the attribute builder.

attributeName - The name of the attribute to access on the component.

type - The expected type of the list elements, used for type checking and casting of the list contents.

Returns:

A builder for creating a ComponentAttribute instance with the specified configuration.