delegatingvariableresolver.java

Please read your package and describe it at least 40 bytes in English. System will automatically de

/*
 * Copyright 2002-2004 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 de.mindmatters.faces.spring.factory;

import javax.faces.context.FacesContext;
import javax.faces.el.VariableResolver;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;

/**
 * <strong>{@link javax.faces.el.VariableResolver}</strong> implementation
 * that delegates to the internal BeanFactory of the used
 * {@link org.springframework.web.context.WebApplicationContext} and original
 * resolver of the underlying JSF implementation to resolve the asked beans or
 * variables.
 * 
 * @author Andreas Kuhrwahl
 * 
 * @see ManagedBeanFactory
 */
public final class DelegatingVariableResolver extends VariableResolver
        implements BeanFactoryAware {

    /**
     * The original configured VariableResolver which is used for delegation.
     */
    private final VariableResolver originalVariableResolver;

    /** The BeanFactory this VariableResolver uses for bean resolving. */
    private BeanFactory beanFactory;

    /**
     * Creates a DelegatingVariableResolver with the given VariableResolver
     * <code>originalVariableResolver</code>.
     * 
     * @param originalVariableResolver
     *            the original resolver of the underlying JSF implementation
     */
    public DelegatingVariableResolver(
            final VariableResolver originalVariableResolver) {
        super();
        this.originalVariableResolver = originalVariableResolver;
    }

    /**
     * Creates a DelegatingVariableResolver with the given VariableResolver
     * <code>originalVariableResolver</code>.
     * 
     * @param originalVariableResolver
     *            the original resolver of the underlying JSF implementation
     * @param beanFactory
     *            The BeanFactory this VariableResolver uses for bean resolving
     */
    public DelegatingVariableResolver(
            final VariableResolver originalVariableResolver,
            final BeanFactory beanFactory) {
        this(originalVariableResolver);
        this.beanFactory = beanFactory;
    }

    /**
     * Checks wether there is a bean with name <code>name</code> in the
     * internal BeanFactory of the used
     * {@link org.springframework.web.context.WebApplicationContext} and returns
     * it. Otherwise delegates to the encapsulated original
     * {@link VariableResolver}.
     * 
     * @param context
     *            context against which to resolve the bean name
     * @param name
     *            name of the bean to be resolved
     * @return the resolved object
     * @throws javax.faces.el.EvaluationException
     *             if an exception is thrown while resolving the variable name
     * 
     * @see VariableResolver#resolveVariable(javax.faces.context.FacesContext,
     *      java.lang.String)
     */
    public Object resolveVariable(final FacesContext context, final String name) {
        Object bean = null;
        boolean beanNotFound = true;
        if (this.beanFactory.containsBean(name)) {
            beanNotFound = false;
            try {
                bean = this.beanFactory.getBean(name);
            } catch (BeansException ex) {
                throw new BeansEvaluationException(ex);
            }
        }
        if (beanNotFound) {
            bean = this.originalVariableResolver.resolveVariable(context, name);
        }
        return bean;
    }

    /**
     * {@inheritDoc}
     */
    public void setBeanFactory(final BeanFactory beanFactory) {
        this.beanFactory = beanFactory;
    }

    /**
     * Returns the encapsulated original VariableResolver of the underlying JSF
     * implementation.
     * 
     * @return the original VariableResolver
     */
    VariableResolver getOriginalVariableResolver() {
        return originalVariableResolver;
    }

}