Java tutorial
/* * $Id$ * -------------------------------------------------------------------------------------- * Copyright (c) MuleSoft, Inc. All rights reserved. http://www.mulesoft.com * * The software in this package is published under the terms of the CPAL v1.0 * license, a copy of which has been included with this distribution in the * LICENSE.txt file. */ package org.mule.config.spring; import org.mule.config.spring.util.SpringXMLUtils; import org.mule.util.StringUtils; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.beans.factory.config.BeanDefinition; import org.springframework.beans.factory.config.BeanDefinitionHolder; import org.springframework.beans.factory.parsing.BeanComponentDefinition; import org.springframework.beans.factory.support.BeanDefinitionReaderUtils; import org.springframework.beans.factory.xml.BeanDefinitionParserDelegate; import org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader; import org.springframework.beans.factory.xml.NamespaceHandler; import org.springframework.beans.factory.xml.ParserContext; import org.springframework.beans.factory.xml.XmlReaderContext; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.NodeList; /** * This parser enables Mule to parse heirarchical bean structures using spring Namespace handling * There are 4 base DefinitionParsers supplied in Mule that most Parsers will extend from, these are * {@link org.mule.config.spring.parsers.AbstractChildDefinitionParser} * {@link org.mule.config.spring.parsers.AbstractMuleBeanDefinitionParser} * {@link org.mule.config.spring.parsers.generic.ChildDefinitionParser} * {@link org.mule.config.spring.parsers.generic.MuleOrphanDefinitionParser} */ public class MuleHierarchicalBeanDefinitionParserDelegate extends BeanDefinitionParserDelegate { public static final String BEANS = "beans"; // cannot find this in Spring api! public static final String MULE_REPEAT_PARSE = "org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.MULE_REPEAT_PARSE"; public static final String MULE_NO_RECURSE = "org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.MULE_NO_RECURSE"; public static final String MULE_FORCE_RECURSE = "org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.MULE_FORCE_RECURSE"; public static final String MULE_NO_REGISTRATION = "org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.MULE_NO_REGISTRATION"; public static final String MULE_POST_CHILDREN = "org.mule.config.spring.MuleHierarchicalBeanDefinitionParserDelegate.MULE_POST_CHILDREN"; private DefaultBeanDefinitionDocumentReader spring; protected static final Log logger = LogFactory.getLog(MuleHierarchicalBeanDefinitionParserDelegate.class); public MuleHierarchicalBeanDefinitionParserDelegate(XmlReaderContext readerContext, DefaultBeanDefinitionDocumentReader spring) { super(readerContext); this.spring = spring; } public BeanDefinition parseCustomElement(Element element, BeanDefinition parent) { if (logger.isDebugEnabled()) { logger.debug("parsing: " + SpringXMLUtils.elementToString(element)); } if (SpringXMLUtils.isBeansNamespace(element)) { return handleSpringElements(element, parent); } else { String namespaceUri = element.getNamespaceURI(); NamespaceHandler handler = getReaderContext().getNamespaceHandlerResolver().resolve(namespaceUri); if (handler == null) { getReaderContext().error("Unable to locate NamespaceHandler for namespace [" + namespaceUri + "]", element); return null; } boolean noRecurse = false; boolean forceRecurse = false; BeanDefinition finalChild; do { ParserContext parserContext = new ParserContext(getReaderContext(), this, parent); finalChild = handler.parse(element, parserContext); registerBean(element, finalChild); noRecurse = noRecurse || testFlag(finalChild, MULE_NO_RECURSE); forceRecurse = forceRecurse || testFlag(finalChild, MULE_FORCE_RECURSE); } while (null != finalChild && testFlag(finalChild, MULE_REPEAT_PARSE)); // Only iterate and parse child mule name-spaced elements. Spring does not do // hierarchical parsing by default so we need to maintain this behavior // for non-mule elements to ensure that we don't break the parsing of any // other custom name-spaces e.g spring-jee. // We also avoid parsing inside elements that have constructed a factory bean // because that means we're dealing with (something like) ChildMapDefinitionParser, // which handles iteration internally (this is a hack needed because Spring doesn't // expose the DP for "<spring:entry>" elements directly). boolean isRecurse; if (noRecurse) { // no recursion takes precedence, as recursion is set by default isRecurse = false; } else { if (forceRecurse) { isRecurse = true; } else { // default behaviour if no control specified isRecurse = SpringXMLUtils.isMuleNamespace(element); } } if (isRecurse) { NodeList list = element.getChildNodes(); for (int i = 0; i < list.getLength(); i++) { if (list.item(i) instanceof Element) { parseCustomElement((Element) list.item(i), finalChild); } } } // If a parser requests post-processing we call again after children called if (testFlag(finalChild, MULE_POST_CHILDREN)) { ParserContext parserContext = new ParserContext(getReaderContext(), this, parent); finalChild = handler.parse(element, parserContext); } return finalChild; } } protected BeanDefinition handleSpringElements(Element element, BeanDefinition parent) { // these are only called if they are at a "top level" - if they are nested inside // other spring elements then spring will handle them itself if (SpringXMLUtils.isLocalName(element, BEANS)) { // the delegate doesn't support the full spring schema, but it seems that // we can invoke the DefaultBeanDefinitionDocumentReader via registerBeanDefinitions // but we need to create a new DOM document from the element first try { Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument(); doc.appendChild(doc.importNode(element, true)); spring.registerBeanDefinitions(doc, getReaderContext()); } catch (ParserConfigurationException e) { throw new RuntimeException(e); } return parent; } else if (SpringXMLUtils.isLocalName(element, PROPERTY_ELEMENT)) { parsePropertyElement(element, parent); return parent; } // i am trying to keep these to a minimum - using anything but "bean" is a recipe // for disaster - we already have problems with "property", for example. // else if (isLocalName(element, MAP_ELEMENT)) // { // // currently unused? // parseMapElement(element, bd); // } // else if (isLocalName(element, LIST_ELEMENT)) // { // // currently unused? // parseListElement(element, bd); // } // else if (isLocalName(element, SET_ELEMENT)) // { // // currently unused? // parseSetElement(element, bd); // } else if (SpringXMLUtils.isLocalName(element, BEAN_ELEMENT)) { BeanDefinitionHolder holder = parseBeanDefinitionElement(element, parent); registerBeanDefinitionHolder(holder); return holder.getBeanDefinition(); } else { throw new IllegalStateException( "Unexpected Spring element: " + SpringXMLUtils.elementToString(element)); } } protected void registerBean(Element ele, BeanDefinition bd) { if (bd == null) { return; } // Check to see if the Bean Definition represents a compound element - one represents a subset of // configuration for the parent bean. Compound bean definitions should not be registered since the properties // set on them are really set on the parent bean. if (!testFlag(bd, MULE_NO_REGISTRATION)) { String name = generateChildBeanName(ele); logger.debug("register " + name + ": " + bd.getBeanClassName()); registerBeanDefinitionHolder(new BeanDefinitionHolder(bd, name)); } } protected void registerBeanDefinitionHolder(BeanDefinitionHolder bdHolder) { //bdHolder = decorateBeanDefinitionIfRequired(ele, bdHolder); // Register the final decorated instance. BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry()); // Send registration event. getReaderContext().fireComponentRegistered(new BeanComponentDefinition(bdHolder)); } protected String generateChildBeanName(Element e) { String id = SpringXMLUtils.getNameOrId(e); if (StringUtils.isBlank(id)) { String parentId = SpringXMLUtils.getNameOrId((Element) e.getParentNode()); return "." + parentId + ":" + e.getLocalName(); } else { return id; } } public static void setFlag(BeanDefinition bean, String flag) { bean.setAttribute(flag, Boolean.TRUE); } public static boolean testFlag(BeanDefinition bean, String flag) { return null != bean && bean.hasAttribute(flag) && bean.getAttribute(flag) instanceof Boolean && ((Boolean) bean.getAttribute(flag)).booleanValue(); } }