承接前文SpringMVC源码情操陶冶-AbstractHandlerMapping，本文将介绍如何注册HandlerMethod对象作为handler

类结构瞧一瞧

public abstract class AbstractHandlerMethodMapping<T> extends AbstractHandlerMapping implements InitializingBean{}

此为抽象方法，并实现了initializingBean接口，其实主要的注册操作则是通过afterPropertiesSet()接口方法来调用的

AbstractHandlerMethodMapping#afterPropertiesSet()-初始化HandlerMethod对象

源码奉上

	@Override

	public void afterPropertiesSet() {

		initHandlerMethods();

	}

转而看initHandlerMethods()，观察是如何实现加载HandlerMethod

	protected void initHandlerMethods() {

		//获取springmvc上下文的所有注册的bean

		String[] beanNames = (this.detectHandlerMethodsInAncestorContexts ?

				BeanFactoryUtils.beanNamesForTypeIncludingAncestors(getApplicationContext(), Object.class) :

				getApplicationContext().getBeanNamesForType(Object.class));

		for (String beanName : beanNames) {

			if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX)) {

				Class<?> beanType = null;

				try {

					beanType = getApplicationContext().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()是抽象方法，主要供子类需要扫描什么类型的bean

				if (beanType != null && isHandler(beanType)) {

					//解析其中的HandlerMethod进行注册

					detectHandlerMethods(beanName);

				}

			}

		}

		//抽象方法，目前尚无实现

		handlerMethodsInitialized(getHandlerMethods());

	}

接下来稍微分析springmvc是如何解析bean并获取其中的HandlerMethod

AbstractHandlerMethodMapping#detectHandlerMethods()解析

源码奉上

	protected void detectHandlerMethods(final Object handler) {

		Class<?> handlerType = (handler instanceof String ?

				getApplicationContext().getType((String) handler) : handler.getClass());

		//因为有些是CGLIB代理生成的，获取真实的类

		final Class<?> userType = ClassUtils.getUserClass(handlerType);

		Map<Method, T> methods = MethodIntrospector.selectMethods(userType,

				new MethodIntrospector.MetadataLookup<T>() {

					@Override

					public T inspect(Method method) {

						try {

							//模板方法获取handlerMethod的mapping属性

							return getMappingForMethod(method, userType);

						}

						catch (Throwable ex) {

							throw new IllegalStateException("Invalid mapping on handler class [" +

									userType.getName() + "]: " + method, ex);

						}

					}

				});

		//对查找到的HandlerMethod进行注册，保存至内部类mappingRegistry对象中

		for (Map.Entry<Method, T> entry : methods.entrySet()) {

			//作下判断，method是否从属于userType

			Method invocableMethod = AopUtils.selectInvocableMethod(entry.getKey(), userType);

			T mapping = entry.getValue();

			registerHandlerMethod(handler, invocableMethod, mapping);

		}

	}

针对唯一的实现类RequestMappingHandlerMapping，上述的mapping属性指代的是RequestMappingInfo对象，内部包含@RequestMapping注解的内部属性，比如method、params、consumes、produces、value以及对应的属性判断类

RequestMappingHandlerMapping-唯一实现类

作为HandlerMethod对象的配置者，我们主要观察其复写的几个方法

RequestMappingHandlerMapping#afterPropertiesSet()

代码奉上

	@Override

	public void afterPropertiesSet() {

		//config为RequestMappingInfo的创建对象

		this.config = new RequestMappingInfo.BuilderConfiguration();

		//设置urlPathHelper默认为UrlPathHelper.class

		this.config.setUrlPathHelper(getUrlPathHelper());

		//默认为AntPathMatcher，路径匹配校验器

		this.config.setPathMatcher(getPathMatcher());

		//是否支持后缀补充，默认为true

		this.config.setSuffixPatternMatch(this.useSuffixPatternMatch);

		//是否添加"/"后缀，默认为true

		this.config.setTrailingSlashMatch(this.useTrailingSlashMatch);

		//是否采用mediaType匹配模式，比如.json/.xml模式的匹配，默认为false

		this.config.setRegisteredSuffixPatternMatch(this.useRegisteredSuffixPatternMatch);

		//mediaType处理类

		this.config.setContentNegotiationManager(getContentNegotiationManager());

		//调用父类进行HandlerMethod的注册工作

		super.afterPropertiesSet();

	}

此处如何设置可通过查看博文>>>SpringMVC源码情操陶冶-AnnotationDrivenBeanDefinitionParser注解解析器

RequestMappingHandlerMapping#isHandler()-判断获取何种类型的Handler

获取@Controller/@RequestMapping注解下的handler

	@Override

	protected boolean isHandler(Class<?> beanType) {

		//优先匹配@Controller

		return (AnnotatedElementUtils.hasAnnotation(beanType, Controller.class) ||

				AnnotatedElementUtils.hasAnnotation(beanType, RequestMapping.class));

	}

RequestMappingHandlerMapping#getMappingForMethod()-获取HandlerMethod对应的mapping属性

此处指的是RequestMappingInfo，主要包含了路径匹配策略、@RequestMapping属性匹配策略，简单源码奉上

	@Override

	protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {

		//对method以及class类都进行创建RequestMappingInfo

		//因为@RequestMapping可以在方法上/类上应用注解

		RequestMappingInfo info = createRequestMappingInfo(method);

		if (info != null) {

			RequestMappingInfo typeInfo = createRequestMappingInfo(handlerType);

			if (typeInfo != null) {

				info = typeInfo.combine(info);

			}

		}

		return info;

	}

由代码可知，其将拼装Class上的@RequestMapping和Method上的@RequestMapping组装成RequestMappingInfo对象，其内部的属性读者有兴趣可自行去分析。

此处对createRequestMappingInfo()方法作下补充

	protected RequestMappingInfo createRequestMappingInfo(

			RequestMapping requestMapping, RequestCondition<?> customCondition) {

		return RequestMappingInfo

				.paths(resolveEmbeddedValuesInPatterns(requestMapping.path()))

				.methods(requestMapping.method())

				.params(requestMapping.params())

				.headers(requestMapping.headers())

				.consumes(requestMapping.consumes())

				.produces(requestMapping.produces())

				.mappingName(requestMapping.name())

				.customCondition(customCondition)

				.options(this.config)

				.build();

	}

小结

• 介绍AbstractHandlerMethodMapping如何创建HandlerMethod，调用者为RequestMappingHandlerMapping，其可通过mvc:annotation-driven注册，具体可查看>>>SpringMVC源码情操陶冶-AnnotationDrivenBeanDefinitionParser注解解析器

• 其中其唯一实现类RequestMappingHandlerMapping主要是获取@Controller下的@RequestMapping注解的方法将其注册为HandlerMethod对象，其余的相关信息则注册为RequestMappingInfo对象供对路径信息匹配

• 其中如何获取HandlerMethod查看前言中的链接即可