/*
* Copyright 2002-2007 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.web.jsf.el;
import java.beans.FeatureDescriptor;
import java.util.Iterator;
import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ELResolver;
import javax.faces.context.FacesContext;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeansException;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.jsf.FacesContextUtils;
/**
* Special JSF 1.2 <code>ELResolver</code> that exposes the Spring
* <code>WebApplicationContext</code> instance under a variable named
* "webApplicationContext".
*
* <p>In contrast to {@link SpringBeanFacesELResolver}, this ELResolver variant
* does <i>not</i> resolve JSF variable names as Spring bean names. It rather
* exposes Spring's root WebApplicationContext <i>itself</i> under a special name,
* and is able to resolve "webApplicationContext.mySpringManagedBusinessObject"
* dereferences to Spring-defined beans in that application context.
*
* <p>Configure this resolver in your <code>faces-config.xml</code> file as follows:
*
* <pre>
* <application>
* ...
* <el-resolver>org.springframework.web.jsf.el.WebApplicationContextFacesELResolver</el-resolver>
* </application></pre>
*
* @author Juergen Hoeller
* @since 2.5
* @see SpringBeanFacesELResolver
* @see org.springframework.web.jsf.FacesContextUtils#getWebApplicationContext
*/
public class WebApplicationContextFacesELResolver extends ELResolver {
/**
* Name of the exposed WebApplicationContext variable: "webApplicationContext".
*/
public static final String WEB_APPLICATION_CONTEXT_VARIABLE_NAME = "webApplicationContext";
/** Logger available to subclasses */
protected final Log logger = LogFactory.getLog(getClass());
@Override
public Object getValue(ELContext elContext, Object base, Object property) throws ELException {
if (base != null) {
if (base instanceof WebApplicationContext) {
WebApplicationContext wac = (WebApplicationContext) base;
String beanName = property.toString();
if (logger.isTraceEnabled()) {
logger.trace("Attempting to resolve property '" + beanName + "' in root WebApplicationContext");
}
if (wac.containsBean(beanName)) {
if (logger.isDebugEnabled()) {
logger.debug("Successfully resolved property '" + beanName + "' in root WebApplicationContext");
}
elContext.setPropertyResolved(true);
try {
return wac.getBean(beanName);
}
catch (BeansException ex) {
throw new ELException(ex);
}
}
else {
// Mimic standard JSF/JSP behavior when base is a Map by returning null.
return null;
}
}
}
else {
if (WEB_APPLICATION_CONTEXT_VARIABLE_NAME.equals(property)) {
elContext.setPropertyResolved(true);
return getWebApplicationContext(elContext);
}
}
return null;
}
@Override
public Class<?> getType(ELContext elContext, Object base, Object property) throws ELException {
if (base != null) {
if (base instanceof WebApplicationContext) {
WebApplicationContext wac = (WebApplicationContext) base;
String beanName = property.toString();
if (logger.isDebugEnabled()) {
logger.debug("Attempting to resolve property '" + beanName + "' in root WebApplicationContext");
}
if (wac.containsBean(beanName)) {
if (logger.isDebugEnabled()) {
logger.debug("Successfully resolved property '" + beanName + "' in root WebApplicationContext");
}
elContext.setPropertyResolved(true);
try {
return wac.getType(beanName);
}
catch (BeansException ex) {
throw new ELException(ex);
}
}
else {
// Mimic standard JSF/JSP behavior when base is a Map by returning null.
return null;
}
}
}
else {
if (WEB_APPLICATION_CONTEXT_VARIABLE_NAME.equals(property)) {
elContext.setPropertyResolved(true);
return WebApplicationContext.class;
}
}
return null;
}
@Override
public void setValue(ELContext elContext, Object base, Object property, Object value) throws ELException {
}
@Override
public boolean isReadOnly(ELContext elContext, Object base, Object property) throws ELException {
if (base instanceof WebApplicationContext) {
elContext.setPropertyResolved(true);
return false;
}
return false;
}
@Override
public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext elContext, Object base) {
return null;
}
@Override
public Class<?> getCommonPropertyType(ELContext elContext, Object base) {
return Object.class;
}
/**
* Retrieve the WebApplicationContext reference to expose.
* <p>The default implementation delegates to FacesContextUtils,
* returning <code>null</code> if no WebApplicationContext found.
* @param elContext the current JSF ELContext
* @return the Spring web application context
* @see org.springframework.web.jsf.FacesContextUtils#getWebApplicationContext
*/
protected WebApplicationContext getWebApplicationContext(ELContext elContext) {
FacesContext facesContext = FacesContext.getCurrentInstance();
return FacesContextUtils.getRequiredWebApplicationContext(facesContext);
}
}
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