/*
* Copyright 2004-2012 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.faces.webflow;
import java.beans.FeatureDescriptor;
import java.util.Iterator;
import javax.el.ELContext;
import javax.el.ELResolver;
import javax.faces.application.Application;
import javax.faces.context.FacesContext;
import org.springframework.util.Assert;
import org.springframework.webflow.execution.RequestContext;
import org.springframework.webflow.execution.RequestContextHolder;
/**
* ELResolver that checks request, session, and application scopes for existing JSF-managed beans. This allows
* traditional JSF-managed beans (defined in faces-config.xml) to be resolved through expressions in a flow definition.
* The preferred approach is to instead use Spring to configure such beans, but this is meant to ease migration for
* users with existing JSF artifacts. This resolver will delegate to a temporary FacesContext so that JSF managed bean
* initialization will be triggered if the bean has not already been initialized by JSF.
*
* @author Jeremy Grelle
* @author Phillip Webb
*/
public class JsfManagedBeanResolver extends ELResolver {
public Class<?> getCommonPropertyType(ELContext context, Object base) {
return Object.class;
}
public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) {
return null;
}
public Class<?> getType(ELContext context, Object base, Object property) {
if (base == null) {
Object bean = getFacesBean(property);
if (bean != null) {
context.setPropertyResolved(true);
return bean.getClass();
}
}
return null;
}
public Object getValue(ELContext context, Object base, Object property) {
if (base == null) {
Object bean = getFacesBean(property);
if (bean != null) {
context.setPropertyResolved(true);
return bean;
}
}
return null;
}
public boolean isReadOnly(ELContext context, Object base, Object property) {
if (base == null) {
RequestContext requestContext = RequestContextHolder.getRequestContext();
if (requestContext.getExternalContext().getRequestMap().contains(property.toString())
|| requestContext.getExternalContext().getSessionMap().contains(property.toString())
|| requestContext.getExternalContext().getApplicationMap().contains(property.toString())) {
context.setPropertyResolved(true);
}
}
return false;
}
/**
* Sets a bean value if a corresponding key is found in one of the ExternalContext scopes.
*/
public void setValue(ELContext context, Object base, Object property, Object value) {
if (base == null) {
RequestContext requestContext = RequestContextHolder.getRequestContext();
if (requestContext.getExternalContext().getRequestMap().contains(property.toString())) {
context.setPropertyResolved(true);
requestContext.getExternalContext().getRequestMap().put(property.toString(), value);
} else if (requestContext.getExternalContext().getSessionMap().contains(property.toString())) {
context.setPropertyResolved(true);
requestContext.getExternalContext().getSessionMap().put(property.toString(), value);
} else if (requestContext.getExternalContext().getApplicationMap().contains(property.toString())) {
context.setPropertyResolved(true);
requestContext.getExternalContext().getApplicationMap().put(property.toString(), value);
}
}
}
/**
* This resolver is only meant to be called from the Flow Execution, thus it assumes that the FacesContext will not
* be available and creates a temporary one on the fly.
* @return The initialized FacesContext.
*/
private FacesContext getFacesContext() {
RequestContext requestContext = RequestContextHolder.getRequestContext();
Assert.notNull(requestContext, "RequestContext cannot be null - This resolver is only intended to be invoked "
+ "from an active Flow Execution.");
FacesContext facesContext = FlowFacesContext.newInstance(requestContext, FlowLifecycle.newInstance());
return facesContext;
}
/**
* Uses a temporary FacesContext to try and resolve a JSF Managed Bean
* @param beanName - The name of the bean to resolve.
* @return The JSF Managed Bean instance if found.
*/
private Object getFacesBean(Object beanName) {
FacesContext context = getFacesContext();
try {
Application application = context.getApplication();
String expression = "#{" + beanName + "}";
return application.evaluateExpressionGet(context, expression, Object.class);
} finally {
context.release();
}
}
}