/*
* 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 javax.el.ELContext;
import javax.el.ExpressionFactory;
import javax.el.ValueExpression;
import javax.faces.context.FacesContext;
import org.springframework.expression.AccessException;
import org.springframework.expression.EvaluationContext;
import org.springframework.expression.PropertyAccessor;
import org.springframework.expression.TypedValue;
import org.springframework.util.Assert;
import org.springframework.webflow.context.ExternalContext;
import org.springframework.webflow.core.collection.MutableAttributeMap;
import org.springframework.webflow.execution.RequestContext;
import org.springframework.webflow.execution.RequestContextHolder;
/**
* <p>
* Spring EL PropertyAccessor 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.
* </p>
* <p>
* 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.
* </p>
* <p>
* Source code adapted from {@link JsfManagedBeanResolver}.
* </p>
*
* @author Jeremy Grelle
* @author Rossen Stoyanchev
*
* @since 2.1
*/
public class JsfManagedBeanPropertyAccessor implements PropertyAccessor {
public Class<?>[] getSpecificTargetClasses() {
return null;
}
public boolean canRead(EvaluationContext context, Object target, String name) throws AccessException {
return (getJsfManagedBean(name) != null);
}
public TypedValue read(EvaluationContext context, Object target, String name) throws AccessException {
return new TypedValue(getJsfManagedBean(name));
}
public boolean canWrite(EvaluationContext context, Object target, String name) throws AccessException {
return (getScopeForBean(name) != null);
}
public void write(EvaluationContext context, Object target, String name, Object newValue) throws AccessException {
MutableAttributeMap<Object> map = getScopeForBean(name);
if (map != null) {
map.put(name, newValue);
}
}
/**
* Locates a JSF managed bean through a temporary FacesContext. This method is only meant to be called from the Flow
* Execution. If a FacesContext is not available, a temporary will be created on the fly.
*
* @param name The name of the bean to resolve.
* @return The JSF Managed Bean instance if found.
*/
private Object getJsfManagedBean(String name) {
RequestContext requestContext = RequestContextHolder.getRequestContext();
Assert.notNull(requestContext, "RequestContext cannot be null. "
+ "This PropertyAccessor is only intended to be invoked from an active Flow Execution.");
boolean releaseFacesContext = false;
FacesContext facesContext = FacesContext.getCurrentInstance();
if (facesContext == null) {
releaseFacesContext = true;
facesContext = FlowFacesContext.newInstance(requestContext, FlowLifecycle.newInstance());
}
try {
ExpressionFactory factory = facesContext.getApplication().getExpressionFactory();
ELContext elContext = facesContext.getELContext();
ValueExpression expression = factory.createValueExpression(elContext, "#{" + name + "}", Object.class);
return expression.getValue(facesContext.getELContext());
} finally {
if (releaseFacesContext) {
facesContext.release();
}
}
}
private MutableAttributeMap<Object> getScopeForBean(String name) {
ExternalContext externalContext = RequestContextHolder.getRequestContext().getExternalContext();
if (externalContext.getRequestMap().contains(name)) {
return externalContext.getRequestMap();
} else if (externalContext.getSessionMap().contains(name)) {
return externalContext.getSessionMap();
} else if (externalContext.getApplicationMap().contains(name)) {
return externalContext.getApplicationMap();
}
return null;
}
}