/*
* RHQ Management Platform
* Copyright (C) 2005-2008 Red Hat, Inc.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation, and/or the GNU Lesser
* General Public License, version 2.1, also as published by the Free
* Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License and the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License
* and the GNU Lesser General Public License along with this program;
* if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.rhq.core.gui.util;
import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ExpressionFactory;
import javax.el.MethodExpression;
import javax.el.ValueExpression;
import javax.faces.FacesException;
import javax.faces.context.FacesContext;
/**
* A set of utility methods for working with EL {@link javax.el.Expression}s within a JSF application.
*
* @author Ian Springer
*/
public abstract class FacesExpressionUtility {
public static ValueExpression createValueExpression(String expression, Class<?> expectedType) {
ValueExpression valueExpression = getExpressionFactory().createValueExpression(getELContext(), expression,
expectedType);
return valueExpression;
}
@SuppressWarnings("unchecked")
public static <T> T getValue(ValueExpression valueExpression, Class<T> expectedType) {
try {
return (T) valueExpression.getValue(getELContext());
} catch (ELException e) {
throw new FacesException(e);
}
}
public static <T> T getValue(String expressionString, Class<T> expectedType) {
return getValue(createValueExpression(expressionString, expectedType), expectedType);
}
public static void setValue(ValueExpression valueExpression, Object value) {
valueExpression.setValue(getELContext(), value);
}
public static MethodExpression createMethodExpression(String expression, Class<?> expectedReturnType,
Class<?>[] expectedParamTypes) {
ExpressionFactory expressionFactory = getExpressionFactory();
return expressionFactory.createMethodExpression(getELContext(), expression, expectedReturnType,
expectedParamTypes);
}
public static String unwrapExpressionString(String configurationExpressionString) {
return configurationExpressionString.substring(2, configurationExpressionString.length() - 1);
}
private static ExpressionFactory getExpressionFactory() {
ExpressionFactory expressionFactory = FacesContext.getCurrentInstance().getApplication().getExpressionFactory();
return expressionFactory;
}
private static ELContext getELContext() {
return FacesContext.getCurrentInstance().getELContext();
}
}