spring 5.1.2 mvc HanderMapping原始碼呼叫handler過程
阿新 • • 發佈:2018-12-03
https://my.oschina.net/zhangxufeng/blog/2177464
AbstractHandlerMapping
/** * Look up a handler for the given request, falling back to the default * handler if no specific one is found. * @param request current HTTP request * @return the corresponding handler instance, or the default handler * @see #getHandlerInternal */ @Override @Nullable public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception { Object handler = getHandlerInternal(request); if (handler == null) { handler = getDefaultHandler(); } if (handler == null) { return null; } // Bean name or resolved handler? if (handler instanceof String) { String handlerName = (String) handler; handler = obtainApplicationContext().getBean(handlerName); } // 獲取當前系統中配置的Interceptor,將其與handler一起封裝為一個HandlerExecutionChain HandlerExecutionChain executionChain = getHandlerExecutionChain(handler, request); if (logger.isTraceEnabled()) { logger.trace("Mapped to " + handler); } else if (logger.isDebugEnabled() && !request.getDispatcherType().equals(DispatcherType.ASYNC)) { logger.debug("Mapped to " + executionChain.getHandler()); } // 這裡CorsUtils.isCorsRequest()方法判斷的是當前請求是否為一個跨域的請求,如果是一個跨域的請求, // 則將跨域相關的配置也一併封裝到HandlerExecutionChain中 if (CorsUtils.isCorsRequest(request)) { CorsConfiguration globalConfig = this.corsConfigurationSource.getCorsConfiguration(request); CorsConfiguration handlerConfig = getCorsConfiguration(handler, request); CorsConfiguration config = (globalConfig != null ? globalConfig.combine(handlerConfig) : handlerConfig); executionChain = getCorsHandlerExecutionChain(request, executionChain, config); } return executionChain; } /** * Build a {@link HandlerExecutionChain} for the given handler, including * applicable interceptors. * <p>The default implementation builds a standard {@link HandlerExecutionChain} * with the given handler, the handler mapping's common interceptors, and any * {@link MappedInterceptor MappedInterceptors} matching to the current request URL. Interceptors * are added in the order they were registered. Subclasses may override this * in order to extend/rearrange the list of interceptors. * <p><b>NOTE:</b> The passed-in handler object may be a raw handler or a * pre-built {@link HandlerExecutionChain}. This method should handle those * two cases explicitly, either building a new {@link HandlerExecutionChain} * or extending the existing chain. * <p>For simply adding an interceptor in a custom subclass, consider calling * {@code super.getHandlerExecutionChain(handler, request)} and invoking * {@link HandlerExecutionChain#addInterceptor} on the returned chain object. * @param handler the resolved handler instance (never {@code null}) * @param request current HTTP request * @return the HandlerExecutionChain (never {@code null}) * @see #getAdaptedInterceptors() */ protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) { HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ? (HandlerExecutionChain) handler : new HandlerExecutionChain(handler)); String lookupPath = this.urlPathHelper.getLookupPathForRequest(request); for (HandlerInterceptor interceptor : this.adaptedInterceptors) { if (interceptor instanceof MappedInterceptor) { MappedInterceptor mappedInterceptor = (MappedInterceptor) interceptor; if (mappedInterceptor.matches(lookupPath, this.pathMatcher)) { chain.addInterceptor(mappedInterceptor.getInterceptor()); } } else { chain.addInterceptor(interceptor); } } return chain; }
AbstractHandlerMethodMapping
// Handler method lookup /** * Look up a handler method for the given request. */ @Override protected HandlerMethod getHandlerInternal(HttpServletRequest request) throws Exception { String lookupPath = getUrlPathHelper().getLookupPathForRequest(request); this.mappingRegistry.acquireReadLock(); try { HandlerMethod handlerMethod = lookupHandlerMethod(lookupPath, request); return (handlerMethod != null ? handlerMethod.createWithResolvedBean() : null); } finally { this.mappingRegistry.releaseReadLock(); } } /** * Look up the best-matching handler method for the current request. * If multiple matches are found, the best match is selected. * @param lookupPath mapping lookup path within the current servlet mapping * @param request the current request * @return the best-matching handler method, or {@code null} if no match * @see #handleMatch(Object, String, HttpServletRequest) * @see #handleNoMatch(Set, String, HttpServletRequest) */ @Nullable protected HandlerMethod lookupHandlerMethod(String lookupPath, HttpServletRequest request) throws Exception { List<Match> matches = new ArrayList<>(); List<T> directPathMatches = this.mappingRegistry.getMappingsByUrl(lookupPath); if (directPathMatches != null) { addMatchingMappings(directPathMatches, matches, request); } if (matches.isEmpty()) { // No choice but to go through all mappings... addMatchingMappings(this.mappingRegistry.getMappings().keySet(), matches, request); } if (!matches.isEmpty()) { Comparator<Match> comparator = new MatchComparator(getMappingComparator(request)); matches.sort(comparator); Match bestMatch = matches.get(0); if (matches.size() > 1) { if (logger.isTraceEnabled()) { logger.trace(matches.size() + " matching mappings: " + matches); } if (CorsUtils.isPreFlightRequest(request)) { return PREFLIGHT_AMBIGUOUS_MATCH; } Match secondBestMatch = matches.get(1); if (comparator.compare(bestMatch, secondBestMatch) == 0) { Method m1 = bestMatch.handlerMethod.getMethod(); Method m2 = secondBestMatch.handlerMethod.getMethod(); String uri = request.getRequestURI(); throw new IllegalStateException( "Ambiguous handler methods mapped for '" + uri + "': {" + m1 + ", " + m2 + "}"); } } handleMatch(bestMatch.mapping, lookupPath, request); return bestMatch.handlerMethod; } else { return handleNoMatch(this.mappingRegistry.getMappings().keySet(), lookupPath, request); } } private void addMatchingMappings(Collection<T> mappings, List<Match> matches, HttpServletRequest request) { for (T mapping : mappings) { T match = getMatchingMapping(mapping, request); if (match != null) { matches.add(new Match(match, this.mappingRegistry.getMappings().get(mapping))); } } }
HandlerMethod
public HandlerMethod createWithResolvedBean() { Object handler = this.bean; if (this.bean instanceof String) { Assert.state(this.beanFactory != null, "Cannot resolve bean name without BeanFactory"); String beanName = (String)this.bean; handler = this.beanFactory.getBean(beanName); } return new HandlerMethod(this, handler); } private HandlerMethod(HandlerMethod handlerMethod, Object handler) { Assert.notNull(handlerMethod, "HandlerMethod is required"); Assert.notNull(handler, "Handler object is required"); this.bean = handler; this.beanFactory = handlerMethod.beanFactory; this.beanType = handlerMethod.beanType; this.method = handlerMethod.method; this.bridgedMethod = handlerMethod.bridgedMethod; this.parameters = handlerMethod.parameters; this.responseStatus = handlerMethod.responseStatus; this.responseStatusReason = handlerMethod.responseStatusReason; this.resolvedFromHandlerMethod = handlerMethod; }