valuebindingresolvingpropertyconfigurer.java

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/*
 * 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 org.springframework.beans.factory.BeanDefinitionStoreException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.BeanNameAware;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanDefinitionVisitor;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.config.ConstructorArgumentValues;
import org.springframework.beans.factory.config.TypedStringValue;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.core.Ordered;

import de.mindmatters.faces.FacesUtils;

/**
 * A property configurer that resolves value bindings in bean property values of
 * context definitions.
 * 
 * <p>
 * The syntax follows the JSF EL style:
 * </p>
 * 
 * <pre>
 *  #{...}
 * </pre>
 * 
 * <p>
 * Example XML context definition:
 * </p>
 * 
 * <pre>
 *  &lt;bean id=&quot;myPerson&quot; class=&quot;foo.Person&quot;&gt;
 *    &lt;property name=&quot;firstname&quot;&gt;&lt;value&gt;John&lt;/value&gt;&lt;/property&gt;
 *    &lt;property name=&quot;lastname&quot;&gt;&lt;value&gt;Doe&lt;/value&gt;&lt;/property&gt;
 *  &lt;/bean&gt;
 *                                                            
 *  &lt;bean id=&quot;info&quot; class=&quot;foo.PersonInfo&quot;&gt;
 *    &lt;property name=&quot;firstnameOfPerson&quot;&gt;&lt;value&gt;#{myPerson.firstname}&lt;/value&gt;&lt;/property&gt;
 *    &lt;property name=&quot;lastnameOfPerson&quot;&gt;&lt;value&gt;#{myPerson.lastname}&lt;/value&gt;&lt;/property&gt;
 *    &lt;property name=&quot;hasPersonSecondname&quot;&gt;&lt;value&gt;#{myPerson.secondname != null}&lt;/value&gt;&lt;/property&gt;
 *  &lt;/bean&gt;
 * </pre>
 * 
 * <p>
 * ValueBindingResolvingPropertyConfigurer checks simple property values, lists,
 * maps, and props.
 * </p>
 * 
 * @author Andreas Kuhrwahl
 */
public final class ValueBindingResolvingPropertyConfigurer implements
        BeanNameAware, BeanFactoryAware, BeanFactoryPostProcessor, Ordered {

    /** The order of this {@link BeanFactoryPostProcessor}. */
    private static final int ORDER = Ordered.HIGHEST_PRECEDENCE + 1;

    /**
     * Visitor class for traversing BeanDefinition objects and the
     * MutablePropertyValues and ConstructorArgumentValues contained in them to
     * resolve value bindings.
     * 
     * @author Andreas Kuhrwahl
     * 
     */
    private class ValueBindingResolvingBeanDefinitionVisitor extends
            BeanDefinitionVisitor {

        /**
         * {@inheritDoc}
         */
        protected String resolveStringValue(final String strVal) {
            return strVal;
        }

        /**
         * {@inheritDoc}
         */
        protected Object resolveValue(final Object value) {
            Object resolvedValue = null;
            if (value instanceof TypedStringValue
                    && FacesUtils.isValueReference(((TypedStringValue) value)
                            .getValue())) {
                resolvedValue = createELResolverFactoryBeanDefinition(((TypedStringValue) value)
                        .getValue());
            } else if (value instanceof String
                    && FacesUtils.isValueReference((String) value)) {
                resolvedValue = createELResolverFactoryBeanDefinition((String) value);
            } else {
                resolvedValue = super.resolveValue(value);
            }
            return resolvedValue;
        }

        /**
         * Creates {@link BeanDefinition} for {@link ELResolverFactoryBean}.
         * 
         * @param expression
         *            the expression
         * @return the {@link BeanDefinition}
         */
        private BeanDefinition createELResolverFactoryBeanDefinition(
                final String expression) {
            RootBeanDefinition elResolverFactoryBean = new RootBeanDefinition(
                    ELResolverFactoryBean.class);
            ConstructorArgumentValues cav = new ConstructorArgumentValues();
            cav.addGenericArgumentValue(expression);
            elResolverFactoryBean.setConstructorArgumentValues(cav);
            return elResolverFactoryBean;
        }

    }

    /** The name of this configurer. */
    private String beanName;

    /** The owning factory to this bean instance. */
    private BeanFactory beanFactory;

    /**
     * {@inheritDoc}
     */
    public void setBeanName(final String name) {
        this.beanName = name;
    }

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

    /**
     * {@inheritDoc}
     */
    public void postProcessBeanFactory(
            final ConfigurableListableBeanFactory beanFactoryToProcess) {
        BeanDefinitionVisitor visitor = new ValueBindingResolvingBeanDefinitionVisitor();
        String[] beanNames = beanFactoryToProcess.getBeanDefinitionNames();
        for (int i = 0; i < beanNames.length; i++) {
            if (!(beanNames[i].equals(this.beanName) && beanFactoryToProcess
                    .equals(this.beanFactory))) {
                BeanDefinition bd = beanFactoryToProcess
                        .getBeanDefinition(beanNames[i]);
                try {
                    visitor.visitBeanDefinition(bd);
                } catch (BeanDefinitionStoreException ex) {
                    throw new BeanDefinitionStoreException(bd
                            .getResourceDescription(), beanNames[i], ex
                            .getMessage());
                }
            }
        }
    }

    /**
     * {@inheritDoc}
     */
    public int getOrder() {
        return ORDER;
    }

}