Spring请求响应

FrameworkServlet类图

	protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {
		HttpServletRequest processedRequest = request;
		HandlerExecutionChain mappedHandler = null;
		boolean multipartRequestParsed = false;

		WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);

		try {
			ModelAndView mv = null;
			Exception dispatchException = null;

			try {
				processedRequest = checkMultipart(request);
				multipartRequestParsed = (processedRequest != request);

				// Determine handler for the current request.
				mappedHandler = getHandler(processedRequest);
				if (mappedHandler == null) {
					noHandlerFound(processedRequest, response);
					return;
				}

				// Determine handler adapter for the current request.
				HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());

				// Process last-modified header, if supported by the handler.
				String method = request.getMethod();
				boolean isGet = "GET".equals(method);
				if (isGet || "HEAD".equals(method)) {
					long lastModified = ha.getLastModified(request, mappedHandler.getHandler());
					if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) {
						return;
					}
				}

				if (!mappedHandler.applyPreHandle(processedRequest, response)) {
					return;
				}

				// Actually invoke the handler.
				mv = ha.handle(processedRequest, response, mappedHandler.getHandler());

				if (asyncManager.isConcurrentHandlingStarted()) {
					return;
				}

				applyDefaultViewName(processedRequest, mv);
				mappedHandler.applyPostHandle(processedRequest, response, mv);
			}
			catch (Exception ex) {
				dispatchException = ex;
			}
			catch (Throwable err) {
				// As of 4.3, we're processing Errors thrown from handler methods as well,
				// making them available for @ExceptionHandler methods and other scenarios.
				dispatchException = new NestedServletException("Handler dispatch failed", err);
			}
			processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
		}
		catch (Exception ex) {
			triggerAfterCompletion(processedRequest, response, mappedHandler, ex);
		}
		catch (Throwable err) {
			triggerAfterCompletion(processedRequest, response, mappedHandler,
					new NestedServletException("Handler processing failed", err));
		}
		finally {
			if (asyncManager.isConcurrentHandlingStarted()) {
				// Instead of postHandle and afterCompletion
				if (mappedHandler != null) {
					mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);
				}
			}
			else {
				// Clean up any resources used by a multipart request.
				if (multipartRequestParsed) {
					cleanupMultipart(processedRequest);
				}
			}
		}
	}

getHandler

整体流程

5 HanlderMapping's in DispatcherServlet

RequestMappingHandlerMapping

AbstractHandlerMethodMapping.getHandlerInternal

@Override
	protected HandlerMethod getHandlerInternal(HttpServletRequest request) throws Exception {
		// request的requestUri
        // 如果请求的javax.servlet.include.context_path或者contextPath不为空
        // 则从requestUri里把开头的contextPath部分给去掉
        String lookupPath = getUrlPathHelper().getLookupPathForRequest(request);
		request.setAttribute(LOOKUP_PATH, lookupPath);
		this.mappingRegistry.acquireReadLock();
		try {
			HandlerMethod handlerMethod = lookupHandlerMethod(lookupPath, request);
			return (handlerMethod != null ? handlerMethod.createWithResolvedBean() : null);
		}
		finally {
			this.mappingRegistry.releaseReadLock();
		}
	}

UrlPathHelper

lookupHandlerMethod

@Nullable
	protected HandlerMethod lookupHandlerMethod(String lookupPath, HttpServletRequest request) throws Exception {
		List<Match> matches = new ArrayList<>();
        // 从mappingRegistry取出匹配上的
		List<T> directPathMatches = this.mappingRegistry.getMappingsByUrl(lookupPath);
		if (directPathMatches != null) {
            // 再加上httpmethod（get post...）去找匹配的，找到匹配的就加进matches里面
			addMatchingMappings(directPathMatches, matches, request);
		}
        // 如果没有匹配上的，就整个mappingRegistry都走一遍
		if (matches.isEmpty()) {
			// No choice but to go through all mappings...
			addMatchingMappings(this.mappingRegistry.getMappings().keySet(), matches, request);
		}

		if (!matches.isEmpty()) {
			Match bestMatch = matches.get(0);
            // 找出最匹配的，
			if (matches.size() > 1) {
				Comparator<Match> comparator = new MatchComparator(getMappingComparator(request));
				matches.sort(comparator);
				bestMatch = matches.get(0);
				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 + "}");
				}
			}
			request.setAttribute(BEST_MATCHING_HANDLER_ATTRIBUTE, bestMatch.handlerMethod);
			handleMatch(bestMatch.mapping, lookupPath, request);
			return bestMatch.handlerMethod;
		}
		else {
			return handleNoMatch(this.mappingRegistry.getMappings().keySet(), lookupPath, request);
		}
	}

@Override
	protected void handleMatch(RequestMappingInfo info, String lookupPath, HttpServletRequest request) {
        //request.attributes增加 org.springframework.web.servlet.HandlerMapping.lookupPath -> /student
		super.handleMatch(info, lookupPath, request);

		String bestPattern;
		Map<String, String> uriVariables;

		Set<String> patterns = info.getPatternsCondition().getPatterns();
		if (patterns.isEmpty()) {
			bestPattern = lookupPath;
			uriVariables = Collections.emptyMap();
		}
		else {
			bestPattern = patterns.iterator().next();
            // 获取路径参数，实际干活的是AntPathMatcher.doMatch
			uriVariables = getPathMatcher().extractUriTemplateVariables(bestPattern, lookupPath);
		}

		request.setAttribute(BEST_MATCHING_PATTERN_ATTRIBUTE, bestPattern);

		if (isMatrixVariableContentAvailable()) {
			Map<String, MultiValueMap<String, String>> matrixVars = extractMatrixVariables(request, uriVariables);
			request.setAttribute(HandlerMapping.MATRIX_VARIABLES_ATTRIBUTE, matrixVars);
		}

		Map<String, String> decodedUriVariables = getUrlPathHelper().decodePathVariables(request, uriVariables);
		request.setAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, decodedUriVariables);

		if (!info.getProducesCondition().getProducibleMediaTypes().isEmpty()) {
			Set<MediaType> mediaTypes = info.getProducesCondition().getProducibleMediaTypes();
			request.setAttribute(PRODUCIBLE_MEDIA_TYPES_ATTRIBUTE, mediaTypes);
		}
	}

• 寻找最匹配的

• bestMatch.handlerMethod

• super.handleMatch

• pathMatcher

getHandlerExecutionChain

	protected HandlerExecutionChain getHandlerExecutionChain(Object handler, HttpServletRequest request) {
		HandlerExecutionChain chain = (handler instanceof HandlerExecutionChain ?
				(HandlerExecutionChain) handler : new HandlerExecutionChain(handler));

		String lookupPath = this.urlPathHelper.getLookupPathForRequest(request, LOOKUP_PATH);
		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;
	}

getHandlerAdapter

ha.handle

argumentResolvers

returnValueHandlers

doInvoke

@ResponseBody

前面截图里的第11个returnValueHandler