org.omnifaces.el

Class ExpressionInspector

java.lang.Object

org.omnifaces.el.ExpressionInspector

public final class ExpressionInspector
extends Object

This class contains methods that inspect expressions to reveal information about them.

Examples

Determine the bean instance and the property value behind a ValueExpression.

 ValueExpression valueExpression = component.getValueExpression("value");
 ValueReference valueReference = ExpressionInspector.getValueReference(context.getELContext(), valueExpression);
 Object bean = methodReference.getBase();
 Object property = methodReference.getProperty();
 

Determine the bean instance and the concrete getter Method behind a ValueExpression.

 ValueExpression valueExpression = component.getValueExpression("value");
 MethodReference methodReference = ExpressionInspector.getMethodReference(context.getELContext(), valueExpression);
 Object bean = methodReference.getBase();
 Method method = methodReference.getMethod();
 

Determine the bean instance and the concrete action Method behind a MethodExpression.

 MethodExpression methodExpression = commandComponent.getActionExpression();
 MethodReference methodReference = ExpressionInspector.getMethodReference(context.getELContext(), methodExpression);
 Object bean = methodReference.getBase();
 Method method = methodReference.getMethod();
 

Since:

1.4

Author:

Arjan Tijms

Method Summary

Modifier and Type	Method and Description
static MethodReference	getMethodReference(ELContext context, MethodExpression methodExpression) Gets a MethodReference from a MethodExpression.
static MethodReference	getMethodReference(ELContext context, ValueExpression valueExpression) Gets a MethodReference from a ValueExpression.
static ValueReference	getValueReference(ELContext context, ValueExpression valueExpression) Gets the ValueReference from a ValueExpression, without any checks whether the property is actually a property or if it isn't a "MethodSuffix".

Methods inherited from class java.lang.Object

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

Method Detail

getValueReference

public static ValueReference getValueReference(ELContext context,
                                               ValueExpression valueExpression)

Gets the ValueReference from a ValueExpression, without any checks whether the property is actually a property or if it isn't a "MethodSuffix". The property is stored as it appears in the expression, and may thus not actually exists. It's up to the caller how to interpret this.

This is also a workaround for the fact that a ValueReference can't be obtained from a TagValueExpression in JSF 2.x (since it doesn't implement getValueReference and its super class just returns null).

Parameters:

context - the context of this evaluation

valueExpression - the value expression being evaluated

Returns:

a ValueReference holding the final base and property where the value expression evaluated to.

getMethodReference

public static MethodReference getMethodReference(ELContext context,
                                                 ValueExpression valueExpression)

Gets a MethodReference from a ValueExpression. If the ValueExpression refers to a method, this will contain the actual method. If it refers to a property, this will contain the corresponding getter method.

Note that in case the expression refers to a method, the method reference contains the method with the name the expression refers to, with a matching number of arguments and a match of types. Overloads with the same amount of parameters are supported, but if the actual arguments match with the types of multiple overloads (e.g. actual argument Long, overloads for Number and Long) a random method will be chosen.

Parameters:

context - the context of this evaluation

valueExpression - the value expression being evaluated

Returns:

a MethodReference holding the final base and Method where the value expression evaluated to.

getMethodReference

public static MethodReference getMethodReference(ELContext context,
                                                 MethodExpression methodExpression)

Gets a MethodReference from a MethodExpression.

Parameters:

context - the context of this evaluation

methodExpression - the method expression being evaluated

Returns:

a MethodReference holding the final base and Method where the method expression evaluated to.

Since:

2.5