Spring Framework example source code file (WebApplicationContextFacesELResolver.java)

This example Spring Framework source code file (WebApplicationContextFacesELResolver.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

attempting, bean, beansexception, class, elexception, elexception, elresolver, javabean, object, object, string, string, successfully, util, web_application_context_variable_name, webapplicationcontext, webapplicationcontext

The Spring Framework WebApplicationContextFacesELResolver.java source code

/*
 * 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 that exposes the Spring
 * <code>WebApplicationContext instance under a variable named
 * "webApplicationContext".
 *
 * <p>In contrast to {@link SpringBeanFacesELResolver}, this ELResolver variant
 * does <i>not resolve JSF variable names as Spring bean names. It rather
 * exposes Spring's root WebApplicationContext <i>itself 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 faces-config.xml 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());


	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;
	}

	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;
	}

	public void setValue(ELContext elContext, Object base, Object property, Object value) throws ELException {
	}

	public boolean isReadOnly(ELContext elContext, Object base, Object property) throws ELException {
		if (base instanceof WebApplicationContext) {
			elContext.setPropertyResolved(true);
			return false;
		}
		return false;
	}

	public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext elContext, Object base) {
		return null;
	}

	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 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);
	}

}