Springmvc注解驱动 注解驱动的解析 通过查看 spring-webmvc-xxx.jar 下的spring.handlers文件可以发现 mvc前缀的标签都是由 MvcNamespaceHandler 来进行解析的。
spring.handlers
1 http\://www.springframework.org/schema/mvc=org.springframework.web.servlet.config.MvcNamespaceHandler
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 public class MvcNamespaceHandler extends NamespaceHandlerSupport { @Override public void init() { registerBeanDefinitionParser("annotation-driven", new AnnotationDrivenBeanDefinitionParser()); registerBeanDefinitionParser("default-servlet-handler", new DefaultServletHandlerBeanDefinitionParser()); registerBeanDefinitionParser("interceptors", new InterceptorsBeanDefinitionParser()); registerBeanDefinitionParser("resources", new ResourcesBeanDefinitionParser()); registerBeanDefinitionParser("view-controller", new ViewControllerBeanDefinitionParser()); registerBeanDefinitionParser("redirect-view-controller", new ViewControllerBeanDefinitionParser()); registerBeanDefinitionParser("status-controller", new ViewControllerBeanDefinitionParser()); registerBeanDefinitionParser("view-resolvers", new ViewResolversBeanDefinitionParser()); registerBeanDefinitionParser("tiles-configurer", new TilesConfigurerBeanDefinitionParser()); registerBeanDefinitionParser("freemarker-configurer", new FreeMarkerConfigurerBeanDefinitionParser()); registerBeanDefinitionParser("groovy-configurer", new GroovyMarkupConfigurerBeanDefinitionParser()); registerBeanDefinitionParser("script-template-configurer", new ScriptTemplateConfigurerBeanDefinitionParser()); registerBeanDefinitionParser("cors", new CorsBeanDefinitionParser()); } }
通过查看其内部唯一的方法 init() 的实现可以确定 <mvc:annotation-driven /> 的解析工作是由 AnnotationDrivenBeanDefinitionParser 类全权负责的。其实现了BeanDefinitionParser接口
唯一的parse()方法
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 class AnnotationDrivenBeanDefinitionParser implements BeanDefinitionParser { public static final String HANDLER_MAPPING_BEAN_NAME = RequestMappingHandlerMapping.class.getName(); public static final String HANDLER_ADAPTER_BEAN_NAME = RequestMappingHandlerAdapter.class.getName(); //....省略其他属性 public BeanDefinition parse(Element element, ParserContext parserContext) { //.....省略代码 //此处注册组件 parserContext.registerComponent(new BeanComponentDefinition(handlerMappingDef, HANDLER_MAPPING_BEAN_NAME)); //注册RequestMappingHandlerMapping parserContext.registerComponent(new BeanComponentDefinition(handlerAdapterDef, HANDLER_ADAPTER_BEAN_NAME)); //注册REquestMappingHandlerAdapter parserContext.registerComponent(new BeanComponentDefinition(uriCompContribDef, uriCompContribName)); parserContext.registerComponent(new BeanComponentDefinition(exceptionResolver, methodExceptionResolverName)); parserContext.registerComponent(new BeanComponentDefinition(statusExceptionResolver, statusExResolverName)); parserContext.registerComponent(new BeanComponentDefinition(defaultExceptionResolver, defaultExResolverName)); parserContext.registerComponent(new BeanComponentDefinition(mappedCsInterceptorDef, mappedInterceptorName)); // Ensure BeanNameUrlHandlerMapping (SPR-8289) and default HandlerAdapters are not "turned off" MvcNamespaceUtils.registerDefaultComponents(parserContext, source); parserContext.popAndRegisterContainingComponent(); return null; } }
观察该类对所继承接口的实现可以发现:
向SpringMVC容器中注册了 ContentNegotiationManagerFactoryBean
RequestMappingHandlerMapping 继承结构 public class RequestMappingHandlerMapping extends RequestMappingInfoHandlerMapping
public abstract class RequestMappingInfoHandlerMapping extends AbstractHandlerMethodMapping
public abstract class AbstractHandlerMethodMapping \<T> extends AbstractHandlerMapping implements InitializingBean
初始化 初始化接口 该类实现了InitializingBean接口，因此初始化bean时会调用afterPropertiesSet()方法
1 2 3 4 5 6 7 8 9 10 11 12 13 14 public interface InitializingBean { /** * Invoked by a BeanFactory after it has set all bean properties supplied * (and satisfied BeanFactoryAware and ApplicationContextAware). * <p>This method allows the bean instance to perform initialization only * possible when all bean properties have been set and to throw an * exception in the event of misconfiguration. * @throws Exception in the event of misconfiguration (such * as failure to set an essential property) or if initialization fails. */ void afterPropertiesSet() throws Exception; }
InitializingBean接口为bean提供了初始化方法的方式，它只包括afterPropertiesSet方法，凡是继承该接口的类，在初始化bean的时候都会执行该方法。
补充说明：
1、Spring为bean提供了两种初始化bean的方式，实现InitializingBean接口，实现afterPropertiesSet方法，或者在配置文件中通过init-method指定，两种方式可以同时使用。
2、实现InitializingBean接口是直接调用afterPropertiesSet方法，比通过反射调用init-method指定的方法效率要高一点，但是init-method方式消除了对spring的依赖。
3、如果调用afterPropertiesSet方法时出错，则不调用init-method指定的方法。
参考：https://www.cnblogs.com/weiqihome/p/8922937.html
具体实现接口 1）public abstract class AbstractHandlerMethodMapping 该类实现了InitializingBean的afterPropertiesSet()方法
AbstractHandlerMethodMapping—>afterPropertiesSet()
1 2 3 4 @Override public void afterPropertiesSet() { initHandlerMethods(); }
调用了initHandlerMethods();
2）AbstractHandlerMethodMapping–>initHandlerMethods();
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 /** * Scan beans in the ApplicationContext, detect and register handler methods. * @see #isHandler(Class) * @see #getMappingForMethod(Method, Class) * @see #handlerMethodsInitialized(Map) */ protected void initHandlerMethods() { if (logger.isDebugEnabled()) { logger.debug("Looking for request mappings in application context: " + getApplicationContext()); } //获取容器中的bean名 String[] beanNames = (this.detectHandlerMethodsInAncestorContexts ? BeanFactoryUtils.beanNamesForTypeIncludingAncestors(obtainApplicationContext(), Object.class) : obtainApplicationContext().getBeanNamesForType(Object.class)); //遍历 for (String beanName : beanNames) { if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX)) { Class<?> beanType = null; try { //根据bean名获取该bean的类型(Class) beanType = obtainApplicationContext().getType(beanName); } catch (Throwable ex) { // An unresolvable bean type, probably from a lazy bean - let's ignore it. if (logger.isDebugEnabled()) { logger.debug("Could not resolve target class for bean with name '" + beanName + "'", ex); } } // isHandler在AbstractHandlerMethodMapping<T>类中抽象方法; //判断是否是一个Handler if (beanType != null && isHandler(beanType)) { //检测Handler中的方法 detectHandlerMethods(beanName); } } } handlerMethodsInitialized(getHandlerMethods()); }
3）String[] beanNames获取容器中的bean名称,然后对bean进行遍历
4）isHandler()方法
RequestMappingHandlerMapping类对父类AbstractHandlerMethodMapping\<T>类的实现
RequestMappingHandlerMapping——–>isHandler
1 2 3 4 5 @Override protected boolean isHandler(Class<?> beanType) { return (AnnotatedElementUtils.hasAnnotation(beanType, Controller.class) || AnnotatedElementUtils.hasAnnotation(beanType, RequestMapping.class)); }
分析：
判断该Bean是否属于Handler
判断依据：是否有Controller注解 ，或者是否有RequestMapping注解
返回一个boolean类型
5）如果是一个Handler,则执行 ————- detectHandlerMethods(beanName)
AbstractHandlerMethodMapping–>detectHandlerMethods(beanName)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 /** * Look for handler methods in a handler. * @param handler the bean name of a handler or a handler instance */ protected void detectHandlerMethods(final Object handler) { Class<?> handlerType = (handler instanceof String ? obtainApplicationContext().getType((String) handler) : handler.getClass()); if (handlerType != null) { final Class<?> userType = ClassUtils.getUserClass(handlerType); Map<Method, T> methods = MethodIntrospector.selectMethods(userType, (MethodIntrospector.MetadataLookup<T>) method -> { try { //获取映射方法 return getMappingForMethod(method, userType); } catch (Throwable ex) { throw new IllegalStateException("Invalid mapping on handler class [" + userType.getName() + "]: " + method, ex); } }); if (logger.isDebugEnabled()) { logger.debug(methods.size() + " request handler methods found on " + userType + ": " + methods); } for (Map.Entry<Method, T> entry : methods.entrySet()) { Method invocableMethod = AopUtils.selectInvocableMethod(entry.getKey(), userType); T mapping = entry.getValue(); registerHandlerMethod(handler, invocableMethod, mapping); } } }
该方法检测Handler（一个Controller）中的方法并进行注册
该方法主要代码分析：（没有详细分析，下次分析）
1）获取userType中的映射方法放入Map集合中
1 2 3 4 5 6 7 8 9 10 Map<Method, T> methods = MethodIntrospector.selectMethods(userType, (MethodIntrospector.MetadataLookup<T>) method -> { try { return getMappingForMethod(method, userType); } catch (Throwable ex) { throw new IllegalStateException("Invalid mapping on handler class [" + userType.getName() + "]: " + method, ex); } });
getMappingForMethod(method, userType)； //返回一个请求映射信息
1）userType为我们自定义的, 被@Controller注解所修饰的类.
1 2 3 4 5 6 7 8 9 10 11 12 13 protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) { // 抽取该方法上注解的@RequestMapping RequestMappingInfo info = createRequestMappingInfo(method); if (info != null) { // 抽取handlerType(即我们自定义的Controller类)上注解的@RequestMapping RequestMappingInfo typeInfo = createRequestMappingInfo(handlerType); if (typeInfo != null) { // 合并两个RequestMapping的信息(controller路径+method) info = typeInfo.combine(info); } } return info; }
createRequestMappingInfo()
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 protected RequestMappingInfo createRequestMappingInfo( RequestMapping requestMapping, @Nullable RequestCondition<?> customCondition) { RequestMappingInfo.Builder builder = RequestMappingInfo /* 这里说明我们是可以在配置@RequestMapping时, 使用spel表达式的; 例如@RequestMapping("/yuyue/${url.mh}/login") */ .paths(resolveEmbeddedValuesInPatterns(requestMapping.path())) .methods(requestMapping.method()) .params(requestMapping.params()) .headers(requestMapping.headers()) .consumes(requestMapping.consumes()) .produces(requestMapping.produces()) .mappingName(requestMapping.name()); if (customCondition != null) { builder.customCondition(customCondition); } return builder.options(this.config).build(); }
2）注册获取到的映射方法
1 2 3 4 5 for (Map.Entry<Method, T> entry : methods.entrySet()) { Method invocableMethod = AopUtils.selectInvocableMethod(entry.getKey(), userType); T mapping = entry.getValue(); registerHandlerMethod(handler, invocableMethod, mapping); }
registerHandlerMethod(handler, invocableMethod, mapping);
1）andler为传入的bean name
AbstractHandlerMethodMapping——->registerHandlerMethod()
1 2 3 protected void registerHandlerMethod(Object handler, Method method, T mapping) { this.mappingRegistry.register(mapping, handler, method); }
AbstractHandlerMethodMapping———>register()
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 public void register(T mapping, Object handler, Method method) { this.readWriteLock.writeLock().lock(); try { HandlerMethod handlerMethod = createHandlerMethod(handler, method); assertUniqueMethodMapping(handlerMethod, mapping); if (logger.isInfoEnabled()) { logger.info("Mapped \"" + mapping + "\" onto " + handlerMethod); } //mappin与hanlderMethod映射 this.mappingLookup.put(mapping, handlerMethod); List<String> directUrls = getDirectUrls(mapping); for (String url : directUrls) { //url与mapping映射 this.urlLookup.add(url, mapping); } String name = null; if (getNamingStrategy() != null) { name = getNamingStrategy().getName(handlerMethod, mapping); addMappingName(name, handlerMethod); } CorsConfiguration corsConfig = initCorsConfiguration(handler, method, mapping); if (corsConfig != null) { this.corsLookup.put(handlerMethod, corsConfig); } this.registry.put(mapping, new MappingRegistration<>(mapping, handlerMethod, directUrls, name)); } finally { this.readWriteLock.writeLock().unlock(); } }
//属性：private final Map<T, HandlerMethod> mappingLookup = new LinkedHashMap<>();
this.mappingLookup.put(mapping, handlerMethod);
mapping:映射路径(例如：/login)
handlerMethod: 包含了bean和方法信息
抽取出来RequestMappingInfo 信息 注册到 LinkedHashMap<RequestMappingInfo,HandlerMethod>类型的全局字段handlerMethods
//属性：private final MultiValueMap<String, T> urlLookup = new LinkedMultiValueMap<>();
this.urlLookup.add(url, mapping);
url:浏览器请求路径(例如：/login)
mapping:映射方法路径(“例如: /login”)
将映射关系注册到urlLookup全局变量中
总结 1)context:component-scan 默认是将所有@Component注解的类扫描进容器;
@Controller自身就是被@Component修饰的
2）mvc:annotation-driven的解析工作是由 AnnotationDrivenBeanDefinitionParser 类全权负责的。
参考：https://blog.csdn.net/lqzkcx3/article/details/78159708