Java Code Examples for javax.faces.component.UIComponent#getValueExpression()

public Object getAsObject(FacesContext context, UIComponent component,
        String value) {

    if (value == null || component.getValueExpression("value") == null) {
        return null;
    }
    @SuppressWarnings("unchecked")
    Class<? extends Enum<?>> enumType = (Class<? extends Enum<?>>) component
            .getValueExpression("value").getType(context.getELContext());
    for (Enum<?> e : enumType.getEnumConstants()) {
        if (e.toString().equals(value)) {
            return e;
        }
    }
    return null;
}
 

/**
 * Return the core value expression of a specified component
 * 
 * @param component
 * @return
 */
public static String getCoreValueExpression(UIComponent component) {
	ValueExpression valueExpression = component.getValueExpression("value");
	if (null != valueExpression) {
		String v = valueExpression.getExpressionString();
		if (null != v) {
			Matcher matcher = EL_EXPRESSION.matcher(v);
			if (matcher.find()) {
				String exp = matcher.group();
				return exp.substring(2, exp.length() - 1);
			}
			return v;
		}
	}
	return null;
}
 

protected Converter resolveConverter(FacesContext context, UIComponent c, Object value) {
	if (!(c instanceof ValueHolder)) {
		return null;
	}

	Converter cnv = ((ValueHolder) c).getConverter();

	if (cnv != null) {
		return cnv;
	} else {
		ValueExpression ve = c.getValueExpression("value");

		if (ve != null) {
			Class<?> valType = ve.getType(context.getELContext());
			

			if (valType != null && (!valType.isPrimitive())) { // workaround for a Mojarra bug (#966)
				return context.getApplication().createConverter(valType);
			} else if (valType != null && (value instanceof String)) { // workaround for the workaround of the Mojarra bug (#977)
				return context.getApplication().createConverter(valType);
			}
		}

		return null;
	}
}
 

private Converter getConverter(FacesContext context, UIComponent component) {
	Converter converter = ((UIInput) component).getConverter();
	if (converter != null) {
		return converter;
	}
	ValueExpression exp = component.getValueExpression("value");
	if (exp == null) {
		return null;
	}
	Class valueType = exp.getType(context.getELContext());
	if (valueType == null) {
		return null;
	}
	return context.getApplication().createConverter(valueType);
}
 

/**
 * <p>
 * Returns the <code>label</code> property from the specified component.
 * </p>
 * Simplified and adapted version of the implementation of Mojarra 2.2.8-b02
 * (see MessageFactory).
 *
 * @param context
 *            - the <code>FacesContext</code> for the current request
 *
 * @return the label, if any, of the component
 */
public static String getLabel(FacesContext context, UIComponent comp) {
	Object o = comp.getAttributes().get("label");
	if (o == null || (o instanceof String && ((String) o).length() == 0)) {
		ValueExpression vex = comp.getValueExpression("label");
		if (null != vex)
			return (String) vex.getValue(context.getELContext());
	}
	if (o == null) {
		// Use the "clientId" if there was no label specified.
		o = comp.getClientId(context);
	}
	return (String) o;
}
 

/**
 * Yields the type of the variable displayed by a component.
 *
 * @param p_component
 *            the UIComponent
 * @return the type (as class)
 */
public static Class<?> getType(UIComponent p_component) {
	ValueExpression valueExpression = p_component.getValueExpression("value");
	if (valueExpression != null) {
		FacesContext context = FacesContext.getCurrentInstance();
		ELContext elContext = context.getELContext();
		return valueExpression.getType(elContext);
	}
	return null;
}
 

/**
 * Which annotations are given to an object displayed by a JSF component?
 *
 * @param p_component
 *            the component
 * @return null if there are no annotations, or if they cannot be accessed
 */
public static Annotation[] readAnnotations(UIComponent p_component) {
	ValueExpression valueExpression = p_component.getValueExpression("value");
	if (valueExpression != null && valueExpression.getExpressionString() != null && valueExpression.getExpressionString().length()>0) {
		return readAnnotations(valueExpression, p_component);
	}
	return null;
}
 

private Converter findImplicitConverter(FacesContext context, UIComponent component) {
	ValueExpression ve = component.getValueExpression("value");

	if (ve != null) {
		Class<?> valueType = ve.getType(context.getELContext());

		if (valueType != null)
			return context.getApplication().createConverter(valueType);
	}

	return null;
}
 

/**
 * Source adapted from Seam's enumConverter. The goal is to get the type to which this component's value is bound.
 * First, check if the valueExpression provides the type. For dropdown-like components, this may not work, so check
 * for SelectItems children.
 * 
 * @param context the current FacesContext
 * @param uiComponent
 * @param validTypes a list of types to look for
 * @return null if a valid type cannot be found
 */
public static Class<?> getValueType(FacesContext context, UIComponent uiComponent, Collection<Class<?>> validTypes) {
	Class<?> valueType = getValueType(context, uiComponent);
	if (valueType != null && isValid(validTypes, valueType)) {
		return valueType;
	}
	else {
		for (UIComponent child : uiComponent.getChildren()) {
			UIComponent c = (UIComponent) child;
			ValueExpression expr = c.getValueExpression("value");
			Object val = expr == null ? null : expr.getValue(context.getELContext());
			if (val != null) {

				valueType = val.getClass();
				if (valueType.isArray() && isValid(validTypes, valueType.getComponentType())) {
					return valueType;
				}
				else if (val instanceof Collection<?>) {
					valueType = ((Collection<?>) val).iterator().next().getClass();
					if (isValid(validTypes, valueType)) {
						return valueType;
					}
				}
			}
		}
	}
	return null;
}
 

public static boolean hasValueExpression(UIComponent component) {
	ValueExpression valueExpression = component.getValueExpression("value");
	return null != valueExpression;
}
 

/**
 * Returns type of the provided attribute name's {@link ValueExpression} of the provided component.
 *
 * @param component Component to get attribute type for.
 * @param attribute Attribute to get type for.
 *
 * @return Type of the provided attribute name's {@link ValueExpression} of the provided component.
 */
public static Class<?> getAttributeType(UIComponent component, String attribute) {
	ValueExpression valueExpression = component.getValueExpression(attribute);
	return valueExpression == null
		? null
		: valueExpression.getType(FacesContext.getCurrentInstance().getELContext());
}
 

/**
 * return the type for the "value" attribute of the given component, if it exists. Return null otherwise.
 * @param context
 * @param comp
 * @return
 */
public static Class<?> getValueType(FacesContext context, UIComponent comp) {
	ValueExpression expr = comp.getValueExpression("value");
	Class<?> valueType = expr == null ? null : expr.getType(context.getELContext());
	return valueType;
}