java spring mvc处理器映射器介绍
目录
- 一、RequestMappingHandlerMapping解析映射简单介绍
- 二、@RequestMapping解析源码流程
- 三、@RequestMapping映射源码流程
- 四、@RequestMapping解析源码
- 五、@RequestMapping映射源码
前言:
- 本文源码基于
spring-framework-5.3.10
。 mvc
是spring
源码中的一个子模块!
一、RequestMappingHandlerMapping解析映射简单介绍
- @RequestMapping通过
RequestMappingHandlerMapping
进行解析! - HandlerMapping是一个根据URL映射到Handler的方法。
RequestMappingHandlerMapping
是HandlerMapping的一个子类!- RequestMappingHandlerMapping他的父类有InitializingBean,所有在spring启动实例化的时候会调用afterPropertiesSet()方法。解析逻辑就在这里。
RequestMappingHandlerMapping
有俩个过程:解析、映射
二、@RequestMapping解析源码流程
- 容器加载,调用
RequestMappingHandlerMapping
的afterPropertiesSet
()。 - 调用父类的
afterPropertiesSet()
方法。 - 调用initHandlerMethods()方法。
- 循环每一个Bean,看方法上有@RequestMapping或者@Controller的Bean。
- 解析
HandlerMethods
,进行封装RequestMappingInfo。 - 将封装好的
RequestMappingInfo
存起来:key为路径,值为mapping(RequestMappingInfo)
三、@RequestMapping映射源码流程
- 请求进来,调用
getHandler
方法。 - 获取当前请求对应的
HandlerMethod
。 - 通过
UrlPathHelper
对象,用于来解析从们的request中解析出请求映射路径。 - 更具路径去
pathLookup
中找。 - 上面没找到,从所有的里面找有通配符的。
- 找到多个进行排序,优先级:? > * > {} >** 。
- 不为空拿到第一个返回。
- 如果为空获取默认的。默认还是空的,直接返回null。
- 封装拦截器,返回。
四、@RequestMapping解析源码
/** * 解析的开始位置。 * 由于实现了InitializingBean,初始化Bean的时候调用这个方法。 * 源码位置:org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.afterPropertiesSet() */ public void afterPropertiesSet() { this.config = new RequestMappingInfo.BuilderConfiguration(); this.config.setTrailingSlashMatch(useTrailingSlashMatch()); // 尾部斜杠 this.config.setContentNegotiationManager(getContentNegotiationManager()); if (getPatternParser() != null) { this.config.setPatternParser(getPatternParser()); Assert.isTrue(!this.useSuffixPatternMatch && !this.useRegisteredSuffixPatternMatch, "Suffix pattern matching not supported with PathPatternParser."); } else { this.config.setSuffixPatternMatch(useSuffixPatternMatch()); this.config.setRegisteredSuffixPatternMatch(useRegisteredSuffixPatternMatch()); this.config.setPathMatcher(getPathMatcher()); } // 调用父类的afterPropertiesSet方法 super.afterPropertiesSet(); } /** * 父类的afterPropertiesSet方法。 * 源码位置:org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.afterPropertiesSet() */ public void afterPropertiesSet() { initHandlerMethods(); } /** * 解析@RequestMapping方法 * 源码位置:org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initHandlerMethods() */ protected void initHandlerMethods() { // 获得所有候选beanName—— 当前容器所有的beanName for (String beanName : getCandidateBeanNames()) { // BeanName不是scopedTarget.开头的 if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX)) { // *处理候选bean——即解析@RequestMapping和映射路径 processCandidateBean(beanName); } } // 解析完所有@RequestMapping的时候调用 handlerMethodsInitialized(getHandlerMethods()); } /** * 处理候选bean——即解析@RequestMapping和映射路径 * 源码位置:org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.processCandidateBean(String) */ protected void processCandidateBean(String beanName) { Class<?> beanType = null; try { // 得到当前BeanName得到这个Bean的类型 beanType = obtainApplicationContext().getType(beanName); } catch (Throwable ex) { // An unresolvable bean type, probably from a lazy bean - let's ignore it. if (logger.isTraceEnabled()) { logger.trace("Could not resolve type for bean '" + beanName + "'", ex); } } // 这一步判断是关键:是否有Controller 或 RequestMapping注解 if (beanType != null && isHandler(beanType)) { // 解析HandlerMethods detectHandlerMethods(beanName); } } /** * 解析HandlerMethods * 源码位置:org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.detectHandlerMethods(Object) */ protected void detectHandlerMethods(Object handler) { Class<?> handlerType = (handler instanceof String ? obtainApplicationContext().getType((String) handler) : handler.getClass()); if (handlerType != null) { Class<?> userType = ClassUtils.getUserClass(handlerType); // 循环所有方法 Map<Method, T> methods = MethodIntrospector.selectMethods(userType, (MethodIntrospector.MetadataLookup<T>) method -> { try { // 根据Method得到Mapping映射 return getMappingForMethod(method, userType); } catch (Throwable ex) { throw new IllegalStateException("Invalid mapping on handler class [" + userType.getName() + "]: " + method, ex); } }); if (logger.isTraceEnabled()) { logger.trace(formatMappings(userType, methods)); } else if (mappingsLogger.isDebugEnabled()) { mappingsLogger.debug(formatMappings(userType, methods)); } // 遍历每一个方法,这里是所有Bean的所有方法 methods.forEach((method, mapping) -> { Method invocableMethod = AopUtils.selectInvocableMethod(method, userType); // pathLookup放入:key为路径,值为mapping(RequestMappingInfo) registerHandlerMethod(handler, invocableMethod, mapping); }); } } /** * 根据Method得到Mapping映射 * 源码位置:org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.getMappingForMethod(Method, Class<?>) */ protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) { // 如果方法上面有@RequestMapping:解析出RequestMappingInfo // RequestMappingInfo 是用来在请求的时候做匹对的 RequestMappingInfo info = createRequestMappingInfo(method); if (info != null) { // 如果方法上面有@RequestMapping,看看类上面是不是有@RequestMapping RequestMappingInfo typeInfo = createRequestMappingInfo(handlerType); // 类上面也有@RequestMapping 那就合并 // 比如 类:/user 方法:/info 合并为 /user/info if (typeInfo != null) { info = typeInfo.combine(info); } // 合并前缀 5.1新增 默认null // 可通过 WebMvcConfigurer#configurePathMatch 进行定制 String prefix = getPathPrefix(handlerType); if (prefix != null) { info = RequestMappingInfo.paths(prefix).options(this.config).build().combine(info); } } return info; } /** * 创建请求映射信息的外部逻辑 * 源码位置:org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.createRequestMappingInfo(AnnotatedElement) */ private RequestMappingInfo createRequestMappingInfo(AnnotatedElement element) { // 获取RequestMapping注解信息 RequestMapping requestMapping = AnnotatedElementUtils.findMergedAnnotation(element, RequestMapping.class); // 获取请求调解:[可扩展], 如果有:该条件会在请求时匹对 RequestCondition<?> condition = (element instanceof Class ? getCustomTypeCondition((Class<?>) element) : getCustomMethodCondition((Method) element)); // 如果有RequestMapping注解,封装成RequestMappingInfo return (requestMapping != null ? createRequestMappingInfo(requestMapping, condition) : null); } /** * 创建请求映射信息的内部逻辑 * 源码位置:org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.createRequestMappingInfo(RequestMapping, RequestCondition<?>) */ protected RequestMappingInfo createRequestMappingInfo( RequestMapping requestMapping, @Nullable RequestCondition<?> customCondition) { // 将@RequestMapping注解属性的值构建成一个 RequestMappingInfo RequestMappingInfo.Builder builder = RequestMappingInfo //构建路径 .paths(resolveEmbeddedValuesInPatterns(requestMapping.path())) //构建方法(get还是post等) .methods(requestMapping.method()) //参数 对应http request parameter .params(requestMapping.params()) //头部 .headers(requestMapping.headers()) //request的提交内容类型content type,如application/json, text/html .consumes(requestMapping.consumes()) //指定返回的内容类型的content type,仅当request请求头中的(Accept)类型中包含该指定类型才返回 .produces(requestMapping.produces()) .mappingName(requestMapping.name()); if (customCondition != null) { builder.customCondition(customCondition); } // 构造RequestMappingInfo:将上面的属性构建成一个个的RequestCondition对象方便在请求的时候组合匹对 return builder.options(this.config).build(); } /** * 得到所有的方法 * 源码位置:org.springframework.core.MethodIntrospector.selectMethods(Class<?>, MetadataLookup<T>) */ public static <T> Map<Method, T> selectMethods(Class<?> targetType, final MetadataLookup<T> metadataLookup) { final Map<Method, T> methodMap = new LinkedHashMap<>(); Set<Class<?>> handlerTypes = new LinkedHashSet<>(); Class<?> specificHandlerType = null; //获取原始的class对象 if (!Proxy.isProxyClass(targetType)) { specificHandlerType = ClassUtils.getUserClass(targetType); handlerTypes.add(specificHandlerType); } //获取class的接口 handlerTypes.addAll(ClassUtils.getAllInterfacesForClassAsSet(targetType)); //循环我们的class集合 for (Class<?> currentHandlerType : handlerTypes) { final Class<?> targetClass = (specificHandlerType != null ? specificHandlerType : currentHandlerType); ReflectionUtils.doWithMethods(currentHandlerType, method -> { //获取具体的方法对象 Method specificMethod = ClassUtils.getMostSpecificMethod(method, targetClass); /**回调 即解析@RequestMapping 返回RequestMappingInfo * @see org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#getMappingForMethod(java.lang.reflect.Method, java.lang.Class)*/ T result = metadataLookup.inspect(specificMethod); if (result != null) { // 看看有没有桥接方法:泛型实现类jvm会自动生成桥接类 Method bridgedMethod = BridgeMethodResolver.findBridgedMethod(specificMethod); if (bridgedMethod == specificMethod || metadataLookup.inspect(bridgedMethod) == null) { //把方法对象作为key,RequestMappingInfo对象作为value保存到map中 methodMap.put(specificMethod, result); } } }, ReflectionUtils.USER_DECLARED_METHODS); } return methodMap; }
五、@RequestMapping映射源码
/** * 获取@RequestMapping映射 * 源码位置:org.springframework.web.servlet.handler.AbstractHandlerMapping.getHandler(HttpServletRequest) */ public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception { // 获取当前请求对应的HandlerMethod Object handler = getHandlerInternal(request); // 获取默认的handler if (handler == null) { handler = getDefaultHandler(); } // 还是没有handler的时候返回null,404了 if (handler == null) { return null; } // Bean name or resolved handler? // String类型?获取Bean if (handler instanceof String) { String handlerName = (String) handler; handler = obtainApplicationContext().getBean(handlerName); } // Ensure presence of cached lookupPath for interceptors and others if (!ServletRequestPathUtils.hasCachedPath(request)) { initLookupPath(request); } // 获取拦截器相关的调用链 HandlerExecutionChain executionChain = getHandlerExecutionChain(handler, request); if (logger.isTraceEnabled()) { logger.trace("Mapped to " + handler); } else if (logger.isDebugEnabled() && !DispatcherType.ASYNC.equals(request.getDispatcherType())) { logger.debug("Mapped to " + executionChain.getHandler()); } if (hasCorsConfigurationSource(handler) || CorsUtils.isPreFlightRequest(request)) { CorsConfiguration config = getCorsConfiguration(handler, request); if (getCorsConfigurationSource() != null) { CorsConfiguration globalConfig = getCorsConfigurationSource().getCorsConfiguration(request); config = (globalConfig != null ? globalConfig.combine(config) : config); } if (config != null) { config.validateAllowCredentials(); } executionChain = getCorsHandlerExecutionChain(request, executionChain, config); } return executionChain; } /** * 获取当前请求对应的HandlerMethod * 源码位置:org.springframework.web.servlet.mvc.method.RequestMappingInfoHandlerMapping.getHandlerInternal(HttpServletRequest) */ protected HandlerMethod getHandlerInternal(HttpServletRequest request) throws Exception { request.removeAttribute(PRODUCIBLE_MEDIA_TYPES_ATTRIBUTE); try { // 直接调用父类的getHandlerInternal方法 return super.getHandlerInternal(request); } finally { ProducesRequestCondition.clearMediaTypesAttribute(request); } } /** * 获取当前请求对应的HandlerMethod---父类的 * 源码位置:org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.getHandlerInternal(HttpServletRequest) */ protected HandlerMethod getHandlerInternal(HttpServletRequest request) throws Exception { // 通过UrlPathHelper对象,用于来解析从们的request中解析出请求映射路径 String lookupPath = initLookupPath(request); this.mappingRegistry.acquireReadLock(); try { // 通过lookupPath解析最终的handler——HandlerMethod对象 HandlerMethod handlerMethod = lookupHandlerMethod(lookupPath, request); return (handlerMethod != null ? handlerMethod.createWithResolvedBean() : null); } finally { this.mappingRegistry.releaseReadLock(); } } /** * 通过lookupPath解析最终的handler * 源码位置:org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.lookupHandlerMethod(String, HttpServletRequest) */ protected HandlerMethod lookupHandlerMethod(String lookupPath, HttpServletRequest request) throws Exception { List<Match> matches = new ArrayList<>(); // 根据uri从mappingRegistry.pathLookup获取 RequestMappingInfo // pathLookup<path,RequestMappingInfo>会在初始化阶段解析好 List<T> directPathMatches = this.mappingRegistry.getMappingsByDirectPath(lookupPath); if (directPathMatches != null) { // 如果根据path能直接匹配的RequestMappingInfo 则用该mapping进行匹配其他条件(method、header等) addMatchingMappings(directPathMatches, matches, request); } if (matches.isEmpty()) { // 如果无path匹配,用所有的RequestMappingInfo 通过AntPathMatcher匹配 addMatchingMappings(this.mappingRegistry.getRegistrations().keySet(), matches, request); } if (!matches.isEmpty()) { // 选择第一个为最匹配的 Match bestMatch = matches.get(0); /** * 如果匹配到多个 @RequestMapping(value="/mappin?") @RequestMapping(value="/mappin*") @RequestMapping(value="/{xxxx}") @RequestMapping(value="/**") */ if (matches.size() > 1) { //创建MatchComparator的匹配器对象 Comparator<Match> comparator = new MatchComparator(getMappingComparator(request)); /** 根据精准度排序 大概是这样的: ? > * > {} >** 具体可以去看: * @see org.springframework.util.AntPathMatcher.AntPatternComparator#compare(java.lang.String, java.lang.String)*/ matches.sort(comparator); // 排完序后拿到优先级最高的 bestMatch = matches.get(0); if (logger.isTraceEnabled()) { logger.trace(matches.size() + " matching mappings: " + matches); } // 是否配置CORS并且匹配 if (CorsUtils.isPreFlightRequest(request)) { for (Match match : matches) { if (match.hasCorsConfig()) { return PREFLIGHT_AMBIGUOUS_MATCH; } } } else { //获取第二最匹配的 Match secondBestMatch = matches.get(1); //若第一个和第二个是一样的 抛出异常 if (comparator.compare(bestMatch, secondBestMatch) == 0) { Method m1 = bestMatch.getHandlerMethod().getMethod(); Method m2 = secondBestMatch.getHandlerMethod().getMethod(); String uri = request.getRequestURI(); throw new IllegalStateException( "Ambiguous handler methods mapped for '" + uri + "': {" + m1 + ", " + m2 + "}"); } } } //把最匹配的设置到request中 request.setAttribute(BEST_MATCHING_HANDLER_ATTRIBUTE, bestMatch.getHandlerMethod()); handleMatch(bestMatch.mapping, lookupPath, request); //返回最匹配的 return bestMatch.getHandlerMethod(); } else { // return null return handleNoMatch(this.mappingRegistry.getRegistrations().keySet(), lookupPath, request); } }
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