/*
* 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;
import javax.faces.context.FacesContext;
import javax.faces.el.EvaluationException;
import javax.faces.el.VariableResolver;
import org.springframework.util.Assert;
import org.springframework.web.context.WebApplicationContext;
/**
* Special JSF 1.1 <code>VariableResolver</code> that exposes the Spring
* <code>WebApplicationContext</code> instance under a variable named
* "webApplicationContext".
*
* <p>In contrast to {@link DelegatingVariableResolver}, this VariableResolver
* 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.
* JSF-managed beans can then use Spring's WebApplicationContext API to retrieve
* Spring-managed beans, access resources, etc.
*
* <p>Configure this resolver in your <code>faces-config.xml</code> file as follows:
*
* <pre>
* <application>
* ...
* <variable-resolver>org.springframework.web.jsf.WebApplicationContextVariableResolver</variable-resolver>
* </application></pre>
*
* @author Colin Sampaleanu
* @author Juergen Hoeller
* @since 1.2.5
* @see DelegatingVariableResolver
* @see FacesContextUtils#getWebApplicationContext
*/
public class WebApplicationContextVariableResolver extends VariableResolver {
/**
* Name of the exposed WebApplicationContext variable: "webApplicationContext".
*/
public static final String WEB_APPLICATION_CONTEXT_VARIABLE_NAME = "webApplicationContext";
protected final VariableResolver originalVariableResolver;
/**
* Create a new WebApplicationContextVariableResolver, using the given
* original VariableResolver.
* <p>A JSF implementation will automatically pass its original resolver into the
* constructor of a configured resolver, provided that there is a corresponding
* constructor argument.
* @param originalVariableResolver the original VariableResolver
*/
public WebApplicationContextVariableResolver(VariableResolver originalVariableResolver) {
Assert.notNull(originalVariableResolver, "Original JSF VariableResolver must not be null");
this.originalVariableResolver = originalVariableResolver;
}
/**
* Return the original JSF VariableResolver that this resolver delegates to.
* Used to resolve standard JSF-managed beans.
*/
protected final VariableResolver getOriginalVariableResolver() {
return this.originalVariableResolver;
}
/**
* Check for the special "webApplicationContext" variable first,
* then delegate to the original VariableResolver.
* <p>If no WebApplicationContext is available, all requests
* will be delegated to the original VariableResolver.
*/
public Object resolveVariable(FacesContext context, String name) throws EvaluationException {
Object value = null;
if (WEB_APPLICATION_CONTEXT_VARIABLE_NAME.equals(name)) {
value = getWebApplicationContext(context);
}
if (value == null) {
value = getOriginalVariableResolver().resolveVariable(context, name);
}
return value;
}
/**
* Retrieve the WebApplicationContext reference to expose.
* <p>The default implementation delegates to FacesContextUtils,
* returning <code>null</code> if no WebApplicationContext found.
* @param facesContext the current JSF context
* @return the Spring web application context
* @see FacesContextUtils#getWebApplicationContext
*/
protected WebApplicationContext getWebApplicationContext(FacesContext facesContext) {
return FacesContextUtils.getWebApplicationContext(facesContext);
}
}