Java tutorial
/* * Copyright 2002-2013 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.integration.config.xml; import java.util.HashSet; import java.util.List; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.springframework.beans.BeanMetadataElement; import org.springframework.beans.factory.BeanDefinitionStoreException; import org.springframework.beans.factory.config.BeanDefinition; import org.springframework.beans.factory.config.BeanDefinitionHolder; import org.springframework.beans.factory.config.RuntimeBeanReference; import org.springframework.beans.factory.support.AbstractBeanDefinition; import org.springframework.beans.factory.support.BeanDefinitionBuilder; import org.springframework.beans.factory.support.BeanDefinitionReaderUtils; import org.springframework.beans.factory.support.ManagedList; import org.springframework.beans.factory.xml.ParserContext; import org.springframework.integration.handler.MessageHandlerChain; import org.springframework.util.StringUtils; import org.springframework.util.xml.DomUtils; /** * Parser for the <chain> element. * * @author Mark Fisher * @author Iwein Fuld * @author Oleg Zhurakousky * @author Artem Bilan * @author Gunnar Hillert */ public class ChainParser extends AbstractConsumerEndpointParser { /** * {@link BeanDefinition} attribute used to pass down the current bean id for nested chains, allowing full * qualification of 'named' handlers within nested chains. * */ private static final String SI_CHAIN_NESTED_ID_ATTRIBUTE = "SI.ChainParser.NestedId.Prefix"; private final Log logger = LogFactory.getLog(this.getClass()); @Override protected BeanDefinitionBuilder parseHandler(Element element, ParserContext parserContext) { BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(MessageHandlerChain.class); if (!StringUtils.hasText(element.getAttribute(ID_ATTRIBUTE))) { logger.info("It is useful to provide an explicit 'id' attribute on 'chain' elements " + "to simplify the identification of child elements in logs etc."); } String chainHandlerId = this.resolveId(element, builder.getRawBeanDefinition(), parserContext); List<BeanMetadataElement> handlerList = new ManagedList<BeanMetadataElement>(); Set<String> handlerBeanNameSet = new HashSet<String>(); NodeList children = element.getChildNodes(); int childOrder = 0; for (int i = 0; i < children.getLength(); i++) { Node child = children.item(i); if (child.getNodeType() == Node.ELEMENT_NODE && !"poller".equals(child.getLocalName())) { BeanMetadataElement childBeanMetadata = this.parseChild(chainHandlerId, (Element) child, childOrder++, parserContext, builder.getBeanDefinition()); if (childBeanMetadata instanceof RuntimeBeanReference) { String handlerBeanName = ((RuntimeBeanReference) childBeanMetadata).getBeanName(); if (!handlerBeanNameSet.add(handlerBeanName)) { parserContext.getReaderContext().error("A bean definition is already registered for " + "beanName: '" + handlerBeanName + "' within the current <chain>.", element); return null; } } if ("gateway".equals(child.getLocalName())) { BeanDefinitionBuilder gwBuilder = BeanDefinitionBuilder.genericBeanDefinition( IntegrationNamespaceUtils.BASE_PACKAGE + ".gateway.RequestReplyMessageHandlerAdapter"); gwBuilder.addConstructorArgValue(childBeanMetadata); handlerList.add(gwBuilder.getBeanDefinition()); } else { handlerList.add(childBeanMetadata); } } } builder.addPropertyValue("handlers", handlerList); IntegrationNamespaceUtils.setValueIfAttributeDefined(builder, element, "send-timeout"); IntegrationNamespaceUtils.setValueIfAttributeDefined(builder, element, "auto-startup"); IntegrationNamespaceUtils.setValueIfAttributeDefined(builder, element, "phase"); return builder; } @Override protected String resolveId(Element element, AbstractBeanDefinition definition, ParserContext parserContext) throws BeanDefinitionStoreException { String id = super.resolveId(element, definition, parserContext); BeanDefinition containingBeanDefinition = parserContext.getContainingBeanDefinition(); if (containingBeanDefinition != null) { String nestedChainIdPrefix = (String) containingBeanDefinition .getAttribute(SI_CHAIN_NESTED_ID_ATTRIBUTE); if (StringUtils.hasText(nestedChainIdPrefix)) { id = nestedChainIdPrefix + "$child." + id; } } definition.setAttribute(SI_CHAIN_NESTED_ID_ATTRIBUTE, id); return id; } private BeanMetadataElement parseChild(String chainHandlerId, Element element, int order, ParserContext parserContext, BeanDefinition parentDefinition) { BeanDefinitionHolder holder = null; String id = element.getAttribute(ID_ATTRIBUTE); boolean hasId = StringUtils.hasText(id); String handlerComponentName = chainHandlerId + "$child" + (hasId ? "." + id : "#" + order); if ("bean".equals(element.getLocalName())) { holder = parserContext.getDelegate().parseBeanDefinitionElement(element, parentDefinition); } else { this.validateChild(element, parserContext); BeanDefinition beanDefinition = parserContext.getDelegate().parseCustomElement(element, parentDefinition); if (beanDefinition == null) { parserContext.getReaderContext().error("child BeanDefinition must not be null", element); return null; } else { holder = new BeanDefinitionHolder(beanDefinition, handlerComponentName + IntegrationNamespaceUtils.HANDLER_ALIAS_SUFFIX); } } holder.getBeanDefinition().getPropertyValues().add("componentName", handlerComponentName); if (hasId) { BeanDefinitionReaderUtils.registerBeanDefinition(holder, parserContext.getRegistry()); return new RuntimeBeanReference(holder.getBeanName()); } return holder; } private void validateChild(Element element, ParserContext parserContext) { final Object source = parserContext.extractSource(element); final String order = element.getAttribute(IntegrationNamespaceUtils.ORDER); if (StringUtils.hasText(order)) { parserContext.getReaderContext().error(IntegrationNamespaceUtils.createElementDescription(element) + " must not define " + "an 'order' attribute when used within a chain.", source); } final List<Element> pollerChildElements = DomUtils.getChildElementsByTagName(element, "poller"); if (!pollerChildElements.isEmpty()) { parserContext.getReaderContext().error(IntegrationNamespaceUtils.createElementDescription(element) + " must not define " + "a 'poller' sub-element when used within a chain.", source); } } }