spring AOP解析之xml方式详解

<aop:config>标签解析

aop名称空间的解析器是AopNamespaceHandler

// 这里我们可以看到注册了几个解析器，重点关注ConfigBeanDefinitionParser

在ConfigBeanDefinitionParser的parse方法中对aop:config下面的三个直接子标签pointcut、advisor、aspect分别进行解析

// 注册AnnotationAwareAspectJAutoProxyCreator或AspectJAwareAdvisorAutoProxyCreatorconfigureAutoProxyCreator(parserContext, element);

List<Element> childElts = DomUtils.getChildElements(element);for (Element elt: childElts) {String localName = parserContext.getDelegate().getLocalName(elt);if (POINTCUT.equals(localName)) {parsePointcut(elt, parserContext);}else if (ADVISOR.equals(localName)) {parseAdvisor(elt, parserContext);}else if (ASPECT.equals(localName)) { parseAspect(elt, parserContext); } }

pointcut标签解析

private AbstractBeanDefinition parsePointcut(Element pointcutElement, ParserContext parserContext) {String id = pointcutElement.getAttribute(ID);String expression = pointcutElement.getAttribute(EXPRESSION);AbstractBeanDefinition pointcutDefinition = null;try {this.parseState.push(new PointcutEntry(id));　　　　　　　// 创建BeanDefinition，下边详解 pointcutDefinition = createPointcutDefinition(expression); pointcutDefinition.setSource(parserContext.extractSource(pointcutElement)); String pointcutBeanName = id; if (StringUtils.hasText(pointcutBeanName)) {　　　　　　　　　// 这里是注册bean parserContext.getRegistry().registerBeanDefinition(pointcutBeanName, pointcutDefinition); } else { pointcutBeanName = parserContext.getReaderContext().registerWithGeneratedName(pointcutDefinition); } parserContext.registerComponent( new PointcutComponentDefinition(pointcutBeanName, pointcutDefinition, expression)); } finally { this.parseState.pop(); } return pointcutDefinition; }

protected AbstractBeanDefinition createPointcutDefinition(String expression) {RootBeanDefinition beanDefinition = new RootBeanDefinition(AspectJExpressionPointcut.class);beanDefinition.setScope(BeanDefinition.SCOPE_PROTOTYPE);beanDefinition.setSynthetic(true);beanDefinition.getPropertyValues().add(EXPRESSION, expression);return beanDefinition;}

我们可以看到RootBeanDefinition的beanClass是AspectJExpressionPointcut，也就是getBean时会实例化AspectJExpressionPointcut，并且为其设置了属性值expression如execution(* com.wjz.service.*.*(..))

我们来看一下AspectJExpressionPointcut的继承结构。这个类同时实现了ClassFilter和MethodMatcher接口执行类匹配和方法匹配逻辑。它有一个expression属性设置表达式，AspectJ最终会把该表达式解析成一个PointcutExpression对象执行相关的语义。后文详解

aspect标签解析

aspect标签的解析要相对复杂一些，解析它下面的所有通知子标签（aop:before、aop:after等标签）

　　　　　　　String aspectId = aspectElement.getAttribute(ID);String aspectName = aspectElement.getAttribute(REF);// 获得所有的通知子标签NodeList nodeList = aspectElement.getChildNodes();boolean adviceFoundAlready = false;for (int i = 0; i < nodeList.getLength(); i++) {Node node = nodeList.item(i);　　　　　　　　 // 判断是否是通知标签如before，after-returning if (isAdviceNode(node, parserContext)) { if (!adviceFoundAlready) { adviceFoundAlready = true; if (!StringUtils.hasText(aspectName)) { parserContext.getReaderContext().error( "<aspect> tag needs aspect bean reference via 'ref' attribute when declaring advices.", aspectElement, this.parseState.snapshot()); return; } beanReferences.add(new RuntimeBeanReference(aspectName)); }　　　　　　　　　　　　// 解析并注册通知子标签，后文详解 AbstractBeanDefinition advisorDefinition = parseAdvice( aspectName, i, aspectElement, (Element) node, parserContext, beanDefinitions, beanReferences); beanDefinitions.add(advisorDefinition); } } AspectComponentDefinition aspectComponentDefinition = createAspectComponentDefinition( aspectElement, aspectId, beanDefinitions, beanReferences, parserContext); parserContext.pushContainingComponent(aspectComponentDefinition); List<Element> pointcuts = DomUtils.getChildElementsByTagName(aspectElement, POINTCUT); for (Element pointcutElement : pointcuts) { parsePointcut(pointcutElement, parserContext); } parserContext.popAndRegisterContainingComponent();

private AbstractBeanDefinition parseAdvice(String aspectName, int order, Element aspectElement, Element adviceElement, ParserContext parserContext,List<BeanDefinition> beanDefinitions, List<BeanReference> beanReferences) {try {this.parseState.push(new AdviceEntry(parserContext.getDelegate().getLocalName(adviceElement)));// 通知标签的方法属性（method属性）会被解析成一个MethodLocatingFactoryBean类型的bean，并设置了methodName属性值　　　　　　　// 为AspectJMethodBeforeAdvice等的构造函数的形参作准备            RootBeanDefinition methodDefinition = new RootBeanDefinition(MethodLocatingFactoryBean.class); methodDefinition.getPropertyValues().add("targetBeanName", aspectName); methodDefinition.getPropertyValues().add("methodName", adviceElement.getAttribute("method")); methodDefinition.setSynthetic(true); // 创建AspectInstanceFactory的一个实例，为AspectJMethodBeforeAdvice等的构造函数的形参作准备

            RootBeanDefinition aspectFactoryDef = new RootBeanDefinition(SimpleBeanFactoryAwareAspectInstanceFactory.class);aspectFactoryDef.getPropertyValues().add("aspectBeanName", aspectName);aspectFactoryDef.setSynthetic(true);// 准备AspectJMethodBeforeAdvice等的构造函数，后文详解AbstractBeanDefinition adviceDef = createAdviceDefinition(adviceElement, parserContext, aspectName, order, methodDefinition, aspectFactoryDef,beanDefinitions, beanReferences);// 解析通知子标签为AspectJPointcutAdvisor对象RootBeanDefinition advisorDefinition = new RootBeanDefinition(AspectJPointcutAdvisor.class);advisorDefinition.setSource(parserContext.extractSource(adviceElement));　　　　　　　// 设置AspectJPointcutAdvisor中的AbstractAspectJAdvice的构造函数参数信息advisorDefinition.getConstructorArgumentValues().addGenericArgumentValue(adviceDef);if (aspectElement.hasAttribute(ORDER_PROPERTY)) { advisorDefinition.getPropertyValues().add( ORDER_PROPERTY, aspectElement.getAttribute(ORDER_PROPERTY)); } // 注册通知子标签  parserContext.getReaderContext().registerWithGeneratedName(advisorDefinition); return advisorDefinition; } finally { this.parseState.pop(); } }

private AbstractBeanDefinition createAdviceDefinition(Element adviceElement, ParserContext parserContext, String aspectName, int order,RootBeanDefinition methodDef, RootBeanDefinition aspectFactoryDef,List<BeanDefinition> beanDefinitions, List<BeanReference> beanReferences) {// getAdviceClass()方法获得AspectJMethodBeforeAdvice、AspectJAfterReturningAdvice等RootBeanDefinition adviceDefinition = new RootBeanDefinition(getAdviceClass(adviceElement, parserContext));adviceDefinition.setSource(parserContext.extractSource(adviceElement));// 添加属性值adviceDefinition.getPropertyValues().add(ASPECT_NAME_PROPERTY, aspectName);adviceDefinition.getPropertyValues().add(DECLARATION_ORDER_PROPERTY, order);if (adviceElement.hasAttribute(RETURNING)) {adviceDefinition.getPropertyValues().add(RETURNING_PROPERTY, adviceElement.getAttribute(RETURNING));}if (adviceElement.hasAttribute(THROWING)) { adviceDefinition.getPropertyValues().add( THROWING_PROPERTY, adviceElement.getAttribute(THROWING)); } if (adviceElement.hasAttribute(ARG_NAMES)) { adviceDefinition.getPropertyValues().add( ARG_NAMES_PROPERTY, adviceElement.getAttribute(ARG_NAMES)); } 　　　　　// 准备AspectJMethodBeforeAdvice等构造函数所需的参数，为构造函数反射得到AspectJMethodBeforeAdvice做准备 ConstructorArgumentValues cav = adviceDefinition.getConstructorArgumentValues(); cav.addIndexedArgumentValue(METHOD_INDEX, methodDef); 　　　　　// 获得pointcut-ref属性值 Object pointcut = parsePointcutProperty(adviceElement, parserContext); if (pointcut instanceof BeanDefinition) { cav.addIndexedArgumentValue(POINTCUT_INDEX, pointcut); beanDefinitions.add((BeanDefinition) pointcut); } else if (pointcut instanceof String) { RuntimeBeanReference pointcutRef = new RuntimeBeanReference((String) pointcut); cav.addIndexedArgumentValue(POINTCUT_INDEX, pointcutRef); beanReferences.add(pointcutRef); } cav.addIndexedArgumentValue(ASPECT_INSTANCE_FACTORY_INDEX, aspectFactoryDef); return adviceDefinition; }

AspectJMethodBeforeAdvice等的构造函数为

advisor标签解析

private void parseAdvisor(Element advisorElement, ParserContext parserContext) {　　　　　// 创建advisor标签对应的BeanDefinition,后文详解AbstractBeanDefinition advisorDef = createAdvisorBeanDefinition(advisorElement, parserContext);String id = advisorElement.getAttribute(ID);try {this.parseState.push(new AdvisorEntry(id));String advisorBeanName = id;　　　　　　　// 注册bean　 if (StringUtils.hasText(advisorBeanName)) { parserContext.getRegistry().registerBeanDefinition(advisorBeanName, advisorDef); } else { advisorBeanName = parserContext.getReaderContext().registerWithGeneratedName(advisorDef); } 　　　　　　　// 获得pointcut-ref属性值，添加属性 Object pointcut = parsePointcutProperty(advisorElement, parserContext); if (pointcut instanceof BeanDefinition) { advisorDef.getPropertyValues().add(POINTCUT, pointcut); parserContext.registerComponent( new AdvisorComponentDefinition(advisorBeanName, advisorDef, (BeanDefinition) pointcut)); } else if (pointcut instanceof String) { advisorDef.getPropertyValues().add(POINTCUT, new RuntimeBeanReference((String) pointcut)); parserContext.registerComponent( new AdvisorComponentDefinition(advisorBeanName, advisorDef)); } } finally { this.parseState.pop(); } }

private AbstractBeanDefinition createAdvisorBeanDefinition(Element advisorElement, ParserContext parserContext) {　　　　　// getBean时实例化一个DefaultBeanFactoryPointcutAdvisorRootBeanDefinition advisorDefinition = new RootBeanDefinition(DefaultBeanFactoryPointcutAdvisor.class);advisorDefinition.setSource(parserContext.extractSource(advisorElement));String adviceRef = advisorElement.getAttribute(ADVICE_REF);if (!StringUtils.hasText(adviceRef)) {parserContext.getReaderContext().error("'advice-ref' attribute contains empty value.", advisorElement, this.parseState.snapshot());}else { advisorDefinition.getPropertyValues().add( ADVICE_BEAN_NAME, new RuntimeBeanNameReference(adviceRef)); } if (advisorElement.hasAttribute(ORDER_PROPERTY)) { advisorDefinition.getPropertyValues().add( ORDER_PROPERTY, advisorElement.getAttribute(ORDER_PROPERTY)); } return advisorDefinition; }

转载于:https://www.cnblogs.com/BINGJJFLY/p/7452703.html