在nanowar中引入AOP
类别: JAVA教程 
通过nanocontainer的nanowar和其struts插件完美的实现了IoC模式的透明，但无法在标准的nanowar中引入nanoaop不得不说是一种遗憾。看了一下nanocontainer的代码，决定自己动手给nanowar添加aop的支持。要在组件和实例中支持AOP，首先要引入interceptor chains。可以考虑在XML定义中引入<aspect interceptor=\'InterceptorName\' pointcuts=\'Filter\'/>标签。这个<aspect>标签与组件或实例的<parameter>标签在同一级别上。其中interceptor指出拦截器的名称。拦截器的实现可以通过标准组件方式在同一个配置文件中进行注册。pointcuts是拦截方法的过滤表达式（perl5的正则表达式，和nanoaop预定义几个过滤规则）。在nanowar中实现这个<aspect>标签，需要修改ScopedCotainerComposer, XMLContainerBuilder, ContainerRecorder, ServletContainerListener, DefaultLifecycleContainerBuider类。由于拦截器无法在IoC容器初始化的过程中得到实例。因此，还需要引入一个新的通用拦截器类（InterceptorDelegate），作为真正的拦截器实例和需被拦截的组件的调用桥梁。由于对源代码改动量较大，索性就在原来类的前面加上Aspectable前缀引入新的类，但除了AOP部分，其他的保持不变。ScopedCotainerComposer => AspectableScopedContainerComposer.java public AspectableScopedContainerComposer() throws ClassNotFoundException { this(new DynaopAspectablePicoContainerFactory().createContainer()); }XMLContainerBuilder => AspectableXMLContainerBuilder.javaprotected PicoContainer createContainerFromScript( .... AspectablePicoContainerFactory containerFactory = new DynaopAspectablePicoContainerFactory(); AspectablePicoContainer childContainer = containerFactory .createContainer(componentAdapterFactory, parentContainer); cuts = childContainer.getPointcutsFactory(); ....} private void registerComponentImplementation(NanoContainer container, Element element) throws ClassNotFoundException, MalformedURLException { ...... Map interceptors = createInterceptors(element); ...... if (interceptors != null) { registerComponentInterceptor(container, clazz, interceptors); } } ....... private void registerComponentInterceptor(NanoContainer container, Class component, String pointcuts, String interceptorKey) { if (notSet(pointcuts)) { pointcuts = ALL_METHODS; } if (container.getPico() instanceof AspectablePicoContainer) { AspectablePicoContainer aspectContainer = (AspectablePicoContainer) container .getPico(); aspectContainer.registerInterceptor(cuts.instancesOf(component), getMethodPointcut(pointcuts), new InterceptorDelegate( aspectContainer, interceptorKey)); } }....... private Map createInterceptors(Element element) { Map interceptorMap = new HashMap(); NodeList children = element.getChildNodes(); for (int i = 0; i < children.getLength(); i++) { if (children.item(i) instanceof Element) { Element childElement = (Element) children.item(i); if (ASPECT.equals(childElement.getNodeName())) { String interceptor = childElement.getAttribute(INTERCEPTOR); if (notSet(interceptor)) throw new NanoContainerMarkupException("\'" + KEY + "\' attribute not specified for " + element.getNodeName()); String pointcuts = childElement.getAttribute(POINTCUTS); interceptorMap.put(interceptor, pointcuts); } } } if (interceptorMap.isEmpty()) return null; else return interceptorMap; } private MethodPointcut getMethodPointcut(String pointcuts) { if (OBJECT_METHODS.equals(pointcuts)) return cuts.objectMethods(); if (IS_METHODS.equals(pointcuts)) return cuts.isMethods(); if (ALL_METHODS.equals(pointcuts)) return cuts.allMethods(); if (GET_METHODS.equals(pointcuts)) return cuts.getMethods(); if (SET_METHODS.equals(pointcuts)) return cuts.setMethods(); return cuts.signature(pointcuts); }ContainerRecorder => AspectableContainerRecorder.java public MutablePicoContainer getContainerProxy() { if (this.container instanceof AspectablePicoContainer) return (MutablePicoContainer) Proxy.newProxyInstance(getClass().getClassLoader(), new Class[]{AspectablePicoContainer.class}, invocationRecorder); else return (MutablePicoContainer) Proxy.newProxyInstance(getClass().getClassLoader(), new Class[]{MutablePicoContainer.class}, invocationRecorder); }DefaultLifecycleContainerBuider => AspectableLifecycleContainerBuider.java protected PicoContainer createContainer(PicoContainer parentContainer, Object assemblyScope) { AspectablePicoContainerFactory containerFactory = new DynaopAspectablePicoContainerFactory(); return containerFactory.createContainer(parentContainer); }ServletContainerListener => AspectableServletContainerListener.javaprivate ContainerBuilder createBuilder(ServletContext context) throws ClassNotFoundException { ...... if (initParameter.equals(CONTAINER_COMPOSER)) { ContainerComposer containerComposer = createContainerComposer(context); return new AspectableLifecycleContainerBuilder(containerComposer); }InterceptorDelegate .javaimport org.aopalliance.intercept.MethodInterceptor;import org.aopalliance.intercept.MethodInvocation;import org.picocontainer.PicoContainer;import dynaop.Interceptor;import dynaop.Invocation;public class InterceptorDelegate implements Interceptor, MethodInterceptor { private PicoContainer pico; private Object key; public InterceptorDelegate(PicoContainer pico, Object key) { this.pico = pico; this.key = key; } /* (non-Javadoc) * @see dynaop.Interceptor#intercept(dynaop.Invocation) */ public Object intercept(Invocation invocation) throws Throwable { return ((Interceptor)pico.getComponentInstance(key)).intercept(invocation); } /* (non-Javadoc) * @see org.aopalliance.intercept.MethodInterceptor#invoke(org.aopalliance.intercept.MethodInvocation) */ public Object invoke(MethodInvocation invocation) throws Throwable { return ((MethodInterceptor)pico.getComponentInstance(key)).invoke(invocation); }}
