Spring Framework example source code file (SpringBeanELResolver.java)

This example Spring Framework source code file (SpringBeanELResolver.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

bean, beanfactory, beanfactory, class, elexception, elexception, elresolver, javabean, log, object, object, spring, springbeanelresolver, string, string, successfully, util

The Spring Framework SpringBeanELResolver.java source code

/*
 * Copyright 2002-2008 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.beans.factory.access.el;

import java.beans.FeatureDescriptor;
import java.util.Iterator;

import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ELResolver;
import javax.el.PropertyNotWritableException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.factory.BeanFactory;

/**
 * Unified EL <code>ELResolver that delegates to a Spring BeanFactory,
 * resolving name references to Spring-defined beans.
 *
 * @author Juergen Hoeller
 * @since 2.5.2
 * @see org.springframework.web.jsf.el.SpringBeanFacesELResolver
 */
public abstract class SpringBeanELResolver extends ELResolver {

	/** 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) {
			String beanName = property.toString();
			if (logger.isTraceEnabled()) {
				logger.trace("Attempting to resolve variable '" + beanName + "' in Spring BeanFactory");
			}
			BeanFactory bf = getBeanFactory(elContext);
			if (bf.containsBean(beanName)) {
				if (logger.isDebugEnabled()) {
					logger.debug("Successfully resolved variable '" + beanName + "' in Spring BeanFactory");
				}
				elContext.setPropertyResolved(true);
				return bf.getBean(beanName);
			}
		}
		return null;
	}

	public Class<?> getType(ELContext elContext, Object base, Object property) throws ELException {
		if (base == null) {
			String beanName = property.toString();
			BeanFactory bf = getBeanFactory(elContext);
			if (bf.containsBean(beanName)) {
				elContext.setPropertyResolved(true);
				return bf.getType(beanName);
			}
		}
		return null;
	}

	public void setValue(ELContext elContext, Object base, Object property, Object value) throws ELException {
		if (base == null) {
			String beanName = property.toString();
			BeanFactory bf = getBeanFactory(elContext);
			if (bf.containsBean(beanName)) {
				throw new PropertyNotWritableException(
						"Variable '" + beanName + "' refers to a Spring bean which by definition is not writable");
			}
		}
	}

	public boolean isReadOnly(ELContext elContext, Object base, Object property) throws ELException {
		if (base == null) {
			String beanName = property.toString();
			BeanFactory bf = getBeanFactory(elContext);
			if (bf.containsBean(beanName)) {
				return true;
			}
		}
		return false;
	}

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

	public Class<?> getCommonPropertyType(ELContext elContext, Object base) {
		return Object.class;
	}


	/**
	 * Retrieve the Spring BeanFactory to delegate bean name resolution to.
	 * @param elContext the current ELContext
	 * @return the Spring BeanFactory (never <code>null)
	 */
	protected abstract BeanFactory getBeanFactory(ELContext elContext);

}