scriptfactorypostprocessor.java

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/*
 * 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.scripting.support;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import net.sf.cglib.asm.Type;
import net.sf.cglib.core.Signature;
import net.sf.cglib.proxy.InterfaceMaker;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.aop.TargetSource;
import org.springframework.aop.framework.AopInfrastructureBean;
import org.springframework.aop.framework.ProxyFactory;
import org.springframework.aop.support.DelegatingIntroductionInterceptor;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.PropertyValue;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.beans.factory.BeanDefinitionStoreException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;
import org.springframework.beans.factory.support.AbstractBeanFactory;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.context.ResourceLoaderAware;
import org.springframework.core.Conventions;
import org.springframework.core.Ordered;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.ResourceLoader;
import org.springframework.scripting.ScriptFactory;
import org.springframework.scripting.ScriptSource;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;

/**
 * {@link org.springframework.beans.factory.config.BeanPostProcessor} that
 * handles {@link org.springframework.scripting.ScriptFactory} definitions,
 * replacing each factory with the actual scripted Java object generated by it.
 *
 * <p>This is similar to the
 * {@link org.springframework.beans.factory.FactoryBean} mechanism, but is
 * specifically tailored for scripts and not built into Spring's core
 * container itself but rather implemented as an extension.
 *
 * <p><b>NOTE:</b> The most important characteristic of this post-processor
 * is that constructor arguments are applied to the
 * {@link org.springframework.scripting.ScriptFactory} instance
 * while bean property values are applied to the generated scripted object.
 * Typically, constructor arguments include a script source locator and
 * potentially script interfaces, while bean property values include
 * references and config values to inject into the scripted object itself.
 *
 * <p>The following {@link ScriptFactoryPostProcessor} will automatically
 * be applied to the two
 * {@link org.springframework.scripting.ScriptFactory} definitions below.
 * At runtime, the actual scripted objects will be exposed for
 * "bshMessenger" and "groovyMessenger", rather than the
 * {@link org.springframework.scripting.ScriptFactory} instances. Both of
 * those are supposed to be castable to the example's <code>Messenger</code>
 * interfaces here.
 *
 * <pre class="code">&lt;bean class="org.springframework.scripting.support.ScriptFactoryPostProcessor"/&gt;
 *
 * &lt;bean id="bshMessenger" class="org.springframework.scripting.bsh.BshScriptFactory"&gt;
 *   &lt;constructor-arg value="classpath:mypackage/Messenger.bsh"/&gt;
 *   &lt;constructor-arg value="mypackage.Messenger"/&gt;
 *   &lt;property name="message" value="Hello World!"/&gt;
 * &lt;/bean&gt;
 *
 * &lt;bean id="groovyMessenger" class="org.springframework.scripting.bsh.GroovyScriptFactory"&gt;
 *   &lt;constructor-arg value="classpath:mypackage/Messenger.groovy"/&gt;
 *   &lt;property name="message" value="Hello World!"/&gt;
 * &lt;/bean&gt;</pre>
 *
 * <p><b>NOTE:</b> Please note that the above excerpt from a Spring
 * XML bean definition file uses just the &lt;bean/&gt;-style syntax
 * (in an effort to illustrate using the {@link ScriptFactoryPostProcessor} itself).
 * In reality, you would never create a &lt;bean/&gt; definition for a
 * {@link ScriptFactoryPostProcessor} explicitly; rather you would import the
 * tags from the <code>'lang'</code> namespace and simply create scripted
 * beans using the tags in that namespace... as part of doing so, a
 * {@link ScriptFactoryPostProcessor} will implicitly be created for you.
 *
 * <p>The Spring reference documentation contains numerous examples of using
 * tags in the <code>'lang'</code> namespace; by way of an example, find below
 * a Groovy-backed bean defined using the <code>'lang:groovy'</code> tag.
 *
 * <pre class="code">
 * &lt;?xml version="1.0" encoding="UTF-8"?&gt;
 * &lt;beans xmlns="http://www.springframework.org/schema/beans"
 *     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 *     xmlns:lang="http://www.springframework.org/schema/lang"&gt;
 *
 *   &lt;!-- this is the bean definition for the Groovy-backed Messenger implementation --&gt;
 *   &lt;lang:groovy id="messenger" script-source="classpath:Messenger.groovy"&gt;
 *     &lt;lang:property name="message" value="I Can Do The Frug" /&gt;
 *   &lt;/lang:groovy&gt;
 *
 *   &lt;!-- an otherwise normal bean that will be injected by the Groovy-backed Messenger --&gt;
 *   &lt;bean id="bookingService" class="x.y.DefaultBookingService"&gt;
 *     &lt;property name="messenger" ref="messenger" /&gt;
 *   &lt;/bean&gt;
 *
 * &lt;/beans&gt;</pre>
 *
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @author Rick Evans
 * @since 2.0
 */
public class ScriptFactoryPostProcessor extends InstantiationAwareBeanPostProcessorAdapter
		implements BeanClassLoaderAware, BeanFactoryAware, ResourceLoaderAware, DisposableBean, Ordered {

	/**
	 * The {@link org.springframework.core.io.Resource}-style prefix that denotes
	 * an inline script.
	 * <p>An inline script is a script that is defined right there in the (typically XML)
	 * configuration, as opposed to being defined in an external file.
	 */
	public static final String INLINE_SCRIPT_PREFIX = "inline:";

	public static final String REFRESH_CHECK_DELAY_ATTRIBUTE =
			Conventions.getQualifiedAttributeName(ScriptFactoryPostProcessor.class, "refreshCheckDelay");

	private static final String SCRIPT_FACTORY_NAME_PREFIX = "scriptFactory.";

	private static final String SCRIPTED_OBJECT_NAME_PREFIX = "scriptedObject.";


	/** Logger available to subclasses */
	protected final Log logger = LogFactory.getLog(getClass());

	private long defaultRefreshCheckDelay = -1;

	private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();

	private AbstractBeanFactory beanFactory;

	private ResourceLoader resourceLoader = new DefaultResourceLoader();

	final DefaultListableBeanFactory scriptBeanFactory = new DefaultListableBeanFactory();

	/** Map from bean name String to ScriptSource object */
	private final Map scriptSourceCache = new HashMap();


	/**
	 * Set the delay between refresh checks, in milliseconds.
	 * Default is -1, indicating no refresh checks at all.
	 * <p>Note that an actual refresh will only happen when
	 * the {@link org.springframework.scripting.ScriptSource} indicates
	 * that it has been modified.
	 * @see org.springframework.scripting.ScriptSource#isModified()
	 */
	public void setDefaultRefreshCheckDelay(long defaultRefreshCheckDelay) {
		this.defaultRefreshCheckDelay = defaultRefreshCheckDelay;
	}

	public void setBeanClassLoader(ClassLoader classLoader) {
		this.beanClassLoader = classLoader;
	}

	public void setBeanFactory(BeanFactory beanFactory) {
		if (!(beanFactory instanceof AbstractBeanFactory)) {
			throw new IllegalStateException(
					"ScriptFactoryPostProcessor must run in AbstractBeanFactory, not in " + beanFactory);
		}
		this.beanFactory = (AbstractBeanFactory) beanFactory;

		// Required so that references (up container hierarchies) are correctly resolved.
		this.scriptBeanFactory.setParentBeanFactory(this.beanFactory);

		// Required so that all BeanPostProcessors, Scopes, etc become available.
		this.scriptBeanFactory.copyConfigurationFrom(this.beanFactory);

		// Filter out BeanPostProcessors that are part of the AOP infrastructure,
		// since those are only meant to apply to beans defined in the original factory.
		for (Iterator it = this.scriptBeanFactory.getBeanPostProcessors().iterator(); it.hasNext();) {
			BeanPostProcessor postProcessor = (BeanPostProcessor) it.next();
			if (postProcessor instanceof AopInfrastructureBean) {
				it.remove();
			}
		}
	}

	public void setResourceLoader(ResourceLoader resourceLoader) {
		this.resourceLoader = resourceLoader;
	}

	public int getOrder() {
		return Integer.MIN_VALUE;
	}


	public Class predictBeanType(Class beanClass, String beanName) {
		// We only apply special treatment to ScriptFactory implementations here.
		if (!ScriptFactory.class.isAssignableFrom(beanClass)) {
			return null;
		}

		RootBeanDefinition bd = this.beanFactory.getMergedBeanDefinition(beanName);
		String scriptFactoryBeanName = SCRIPT_FACTORY_NAME_PREFIX + beanName;
		String scriptedObjectBeanName = SCRIPTED_OBJECT_NAME_PREFIX + beanName;
		prepareScriptBeans(bd, scriptFactoryBeanName, scriptedObjectBeanName);

		ScriptFactory scriptFactory =
				(ScriptFactory) this.scriptBeanFactory.getBean(scriptFactoryBeanName, ScriptFactory.class);
		ScriptSource scriptSource =
				getScriptSource(scriptFactoryBeanName, scriptFactory.getScriptSourceLocator());
		Class[] interfaces = scriptFactory.getScriptInterfaces();

		Class scriptedType = null;
		try {
			scriptedType = scriptFactory.getScriptedObjectType(scriptSource);
		}
		catch (Exception ex) {
			if (logger.isDebugEnabled()) {
				logger.debug("Could not determine the scripted object type for script factory [" + scriptFactory + "]", ex);
			}
		}

		if (scriptedType != null) {
			return scriptedType;
		}
		else if (ObjectUtils.isEmpty(interfaces)) {
			if (bd.isSingleton()) {
				return this.scriptBeanFactory.getBean(scriptedObjectBeanName).getClass();
			}
			else {
				return null;
			}
		}
		else {
			return (interfaces.length == 1 ? interfaces[0] : createCompositeInterface(interfaces));