SpringMVC源码情操陶冶-InterceptorsBeanDefinitionParser拦截器解析器

时间：2021-07-21 15:47:38

解析mvc:interceptors节点

观察下InterceptorsBeanDefinitionParser的源码备注

/**

 * {@link org.springframework.beans.factory.xml.BeanDefinitionParser} that parses a

 * {@code interceptors} element to register a set of {@link MappedInterceptor} definitions.

 *

 * @author Keith Donald

 * @since 3.0

 */

从官方注释可知，此解析器的作用是解析mvc:interceptors节点并注册成MappedInterceptorsDefinition集合

mvc:interceptors的配置使用

    <!-- 拦截器设置 -->

    <mvc:interceptors>

    	<mvc:interceptor>

    		<mvc:mapping path="/**"/>

			  <!-- 静态资源不拦截 -->

    		<mvc:exclude-mapping path="/mobile/**"/>

    		<mvc:exclude-mapping path="/pc/**"/>

    		<!-- 主页不拦截 -->

    		<!-- 特殊user资源获取不拦截 -->

    		<bean class="com.du.wx.interceptor.UserInterceptor" />

    	</mvc:interceptor>

    </mvc:interceptors>

InterceptorsBeanDefinitionParser#parse

直接观察公用接口方法parse()，源码奉上

	@Override

	public BeanDefinition parse(Element element, ParserContext parserContext) {

		//CompositeComponentDefinition表示其可以装载多个ComponentDefinition

		CompositeComponentDefinition compDefinition = new CompositeComponentDefinition(element.getTagName(), parserContext.extractSource(element));

		parserContext.pushContainingComponent(compDefinition);

		//允许mvc:interceptors拥有path-matcher属性，表示 路径匹配解析器

		RuntimeBeanReference pathMatcherRef = null;

		if (element.hasAttribute("path-matcher")) {

			pathMatcherRef = new RuntimeBeanReference(element.getAttribute("path-matcher"));

		}

		//查询mvc:interceptors节点下的bean/ref/interceptor标签

		List<Element> interceptors = DomUtils.getChildElementsByTagName(element, "bean", "ref", "interceptor");

		for (Element interceptor : interceptors) {

			//采用MappedInterceptor作为beanClass

			RootBeanDefinition mappedInterceptorDef = new RootBeanDefinition(MappedInterceptor.class);

			mappedInterceptorDef.setSource(parserContext.extractSource(interceptor));

			mappedInterceptorDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);

			ManagedList<String> includePatterns = null;

			ManagedList<String> excludePatterns = null;

			Object interceptorBean;

			//解析mvc:interceptor节点

			if ("interceptor".equals(interceptor.getLocalName())) {

				//解析mvc:mapping节点中的path属性，保存里面的拦截路径集合

				includePatterns = getIncludePatterns(interceptor, "mapping");

				//解析mvc:exclude-mapping节点中的path属性，保存里面的放行路径集合

				excludePatterns = getIncludePatterns(interceptor, "exclude-mapping");

				//解析bean标签/ref标签，并封装成beanDefinition

				Element beanElem = DomUtils.getChildElementsByTagName(interceptor, "bean", "ref").get(0);

				interceptorBean = parserContext.getDelegate().parsePropertySubElement(beanElem, null);

			}

			else {

			//解析bean标签/ref标签，并封装成beanDefinition

				interceptorBean = parserContext.getDelegate().parsePropertySubElement(interceptor, null);

			}

			//MappedInterceptor类的构造函数可接受三个参数

			/**

			**public MappedInterceptor(String[] includePatterns, String[] excludePatterns, HandlerInterceptor interceptor)

			**

			*/

			mappedInterceptorDef.getConstructorArgumentValues().addIndexedArgumentValue(0, includePatterns);

			mappedInterceptorDef.getConstructorArgumentValues().addIndexedArgumentValue(1, excludePatterns);

			mappedInterceptorDef.getConstructorArgumentValues().addIndexedArgumentValue(2, interceptorBean);

			//为MappedInterceptor添加pathMatcher属性

			if (pathMatcherRef != null) {

				mappedInterceptorDef.getPropertyValues().add("pathMatcher", pathMatcherRef);

			}

			//保存到spring的bean工厂中

			String beanName = parserContext.getReaderContext().registerWithGeneratedName(mappedInterceptorDef);

			parserContext.registerComponent(new BeanComponentDefinition(mappedInterceptorDef, beanName));

		}

		parserContext.popAndRegisterContainingComponent();

		return null;

	}

小结

  • 解析mvc:interceptors，其会封装为MappedInterceptor类，进而保存
  1. 拦截路径匹配集合includePatterns
  2. 不拦截路径匹配集合excludePatterns
  3. 拦截处理器interceptor，其必须是HandlerInterceptor的实现类
  4. 路径匹配处理器，如果mvc:interceptors设定了path-matcher属性，默认为AntPathMatcher

  • MappedInterceptor其内部包含了HandlerInterceptor集合，并添加了路径的映射属性。对匹配的路径调用相应的HandlerInterceptors

  • mvc:interceptors注册的拦截器在AbstractHandlerMapping类中通过matches()方法被调用，具体调用见Springmvc源码

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