Spring Webflux DispatcherHandler源码整理

DispatcherHandler的构造(以RequestMappingHandlerMapping为例)

1. WebFluxAutoConfiguration中EnableWebFluxConfiguration继承WebFluxConfigurationSupport

   @Bean
   public DispatcherHandler webHandler() {return new DispatcherHandler();
   }
   

2. DispatcherHandler#setApplicationContext => initStrategies(applicationContext)

   protected void initStrategies(ApplicationContext context) {Map<String, HandlerMapping> mappingBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerMapping.class, true, false);ArrayList<HandlerMapping> mappings = new ArrayList<>(mappingBeans.values());AnnotationAwareOrderComparator.sort(mappings);this.handlerMappings = Collections.unmodifiableList(mappings);//Map<String, HandlerAdapter> adapterBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerAdapter.class, true, false);//this.handlerAdapters = new ArrayList<>(adapterBeans.values());AnnotationAwareOrderComparator.sort(this.handlerAdapters);//Map<String, HandlerResultHandler> beans = BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerResultHandler.class, true, false);this.resultHandlers = new ArrayList<>(beans.values());AnnotationAwareOrderComparator.sort(this.resultHandlers);
   }
   

3. RequestMappingHandlerMapping-> afterPropertiesSet -> AbstractHandlerMethodMapping.initHandlerMethods

   protected void initHandlerMethods() {String[] beanNames = obtainApplicationContext().getBeanNamesForType(Object.class);for (String beanName : beanNames) {if (!beanName.startsWith(SCOPED_TARGET_NAME_PREFIX)) {Class<?> beanType = obtainApplicationContext().getType(beanName);// 当类被Controller或则RequestMapping标注时查找HandlerMethodif (beanType != null && isHandler(beanType)) {detectHandlerMethods(beanName);}}}}
   

4. AbstractHandlerMethodMapping#detectHandlerMethods(beanName)

    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 -> getMappingForMethod(method, userType));methods.forEach((method, mapping) -> {Method invocableMethod = AopUtils.selectInvocableMethod(method, userType);// invocableMethod保存到MappingRegistry注册表中registerHandlerMethod(handler, invocableMethod, mapping);});}}
   

5. RequestMappingHandlerMapping#getMappingForMethod(method, handlerType)

   protected RequestMappingInfo getMappingForMethod(Method method, Class<?> handlerType) {RequestMappingInfo info = createRequestMappingInfo(method);if (info != null) {RequestMappingInfo typeInfo = createRequestMappingInfo(handlerType);if (typeInfo != null) {info = typeInfo.combine(info);}for (Map.Entry<String, Predicate<Class<?>>> entry : this.pathPrefixes.entrySet()) {if (entry.getValue().test(handlerType)) {String prefix = entry.getKey();if (this.embeddedValueResolver != null) {prefix = this.embeddedValueResolver.resolveStringValue(prefix);}info = RequestMappingInfo.paths(prefix).options(this.config).build().combine(info);break;}}}return info;
   }
   

6. RequestMappingHandlerMapping#createRequestMappingInfo(method)

   private RequestMappingInfo createRequestMappingInfo(AnnotatedElement element) {RequestMapping requestMapping = AnnotatedElementUtils.findMergedAnnotation(element, RequestMapping.class);RequestCondition<?> condition = (element instanceof Class ?getCustomTypeCondition((Class<?>) element) : getCustomMethodCondition((Method) element));return (requestMapping != null ? createRequestMappingInfo(requestMapping, condition) : null);
   }
   protected RequestMappingInfo createRequestMappingInfo(RequestMapping requestMapping, @Nullable RequestCondition<?> customCondition) {RequestMappingInfo.Builder builder = RequestMappingInfo.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();}
   

DispatcherHandler的执行(以RequestMappingHandlerMapping为例)

查找handler

1. DispatcherHandler#handle(exchange)

   public Mono<Void> handle(ServerWebExchange exchange) {if (CorsUtils.isPreFlightRequest(exchange.getRequest())) {return handlePreFlight(exchange);}return Flux.fromIterable(this.handlerMappings).concatMap(mapping -> mapping.getHandler(exchange)).next().switchIfEmpty(createNotFoundError()).flatMap(handler -> invokeHandler(exchange, handler)).flatMap(result -> handleResult(exchange, result));
   }
   

2. AbstractHandlerMapping#getHandler(exchange)

   public Mono<Object> getHandler(ServerWebExchange exchange) {return getHandlerInternal(exchange) ;
   }
   

3. AbstractHandlerMethodMapping#getHandlerInternal

   public Mono<HandlerMethod> getHandlerInternal(ServerWebExchange exchange) {this.mappingRegistry.acquireReadLock();try {HandlerMethod handlerMethod;try {handlerMethod = lookupHandlerMethod(exchange);}catch (Exception ex) {return Mono.error(ex);}if (handlerMethod != null) {handlerMethod = handlerMethod.createWithResolvedBean();}return Mono.justOrEmpty(handlerMethod);}finally {this.mappingRegistry.releaseReadLock();}
   }
   

4. AbstractHandlerMethodMapping#lookupHandlerMethod(exchange)

   protected HandlerMethod lookupHandlerMethod(ServerWebExchange exchange) throws Exception {List<Match> matches = new ArrayList<>();List<T> directPathMatches = this.mappingRegistry.getMappingsByDirectPath(exchange);if (directPathMatches != null) {addMatchingMappings(directPathMatches, matches, exchange);}// 省略部分代码if (!matches.isEmpty()) {Comparator<Match> comparator = new MatchComparator(getMappingComparator(exchange));matches.sort(comparator);Match bestMatch = matches.get(0);handleMatch(bestMatch.mapping, bestMatch.getHandlerMethod(), exchange);return bestMatch.getHandlerMethod();}else {return handleNoMatch(this.mappingRegistry.getRegistrations().keySet(), exchange);}
   }
   

执行handler

1. DispatcherHandler#invokeHandler

   private Mono<HandlerResult> invokeHandler(ServerWebExchange exchange, Object handler) {for (HandlerAdapter handlerAdapter : this.handlerAdapters) {if (handlerAdapter.supports(handler)) {return handlerAdapter.handle(exchange, handler);}}return Mono.error(new IllegalStateException("No HandlerAdapter: " + handler));
   }
   

2. RequestMappingHandlerAdapter#handle(exchange, handler)

   public Mono<HandlerResult> handle(ServerWebExchange exchange, Object handler) {HandlerMethod handlerMethod = (HandlerMethod) handler;InitBinderBindingContext bindingContext = new InitBinderBindingContext(getWebBindingInitializer(), this.methodResolver.getInitBinderMethods(handlerMethod));InvocableHandlerMethod invocableMethod = this.methodResolver.getRequestMappingMethod(handlerMethod);//Function<Throwable, Mono<HandlerResult>> exceptionHandler =ex -> handleException(ex, handlerMethod, bindingContext, exchange);//return this.modelInitializer.initModel(handlerMethod, bindingContext, exchange).then(Mono.defer(() -> invocableMethod.invoke(exchange, bindingContext))).doOnNext(result -> result.setExceptionHandler(exceptionHandler)).doOnNext(result -> bindingContext.saveModel()).onErrorResume(exceptionHandler);
   }
   

3. InvocableHandlerMethod#invoke

   public Mono<HandlerResult> invoke(ServerWebExchange exchange, BindingContext bindingContext, Object... providedArgs) {return getMethodArgumentValues(exchange, bindingContext, providedArgs).flatMap(args -> {Object value;Method method = getBridgedMethod();if (KotlinDetector.isSuspendingFunction(method)) {value = CoroutinesUtils.invokeSuspendingFunction(method, getBean(), args);}else {value = method.invoke(getBean(), args);}// 省略部分代码HttpStatus status = getResponseStatus();if (status != null) {exchange.getResponse().setStatusCode(status);}MethodParameter returnType = getReturnType();ReactiveAdapter adapter = this.reactiveAdapterRegistry.getAdapter(returnType.getParameterType());boolean asyncVoid = isAsyncVoidReturnType(returnType, adapter);if ((value == null || asyncVoid) && isResponseHandled(args, exchange)) {return (asyncVoid ? Mono.from(adapter.toPublisher(value)) : Mono.empty());}HandlerResult result = new HandlerResult(this, value, returnType, bindingContext);return Mono.just(result);});
   }
   

处理返回结果

1. DispatcherHandler#handleResult

   private Mono<Void> handleResult(ServerWebExchange exchange, HandlerResult result) {return getResultHandler(result).handleResult(exchange, result) ;
   }
   

2. DispatcherHandler#getResultHandler => ResponseBodyResultHandler
3. ResponseBodyResultHandler#handleResult(exchange, result)

   public Mono<Void> handleResult(ServerWebExchange exchange, HandlerResult result) {Object body = result.getReturnValue();MethodParameter bodyTypeParameter = result.getReturnTypeSource();return writeBody(body, bodyTypeParameter, exchange);
   }