doDispatch()
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); // 为以后申请匹配处理器（HandlerExecutionChain） mappedHandler = getHandler(processedRequest); if (mappedHandler == null) { noHandlerFound(processedRequest, response); return; } // 为以后申请匹配HandlerAdapter 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); } ... processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException); } ... }HandlerExecutionChain.class
处理器实质上蕴含了HandleMethod和HandlerInterceptor的执行链
public class HandlerExecutionChain { // 此处的handler通常为HandleMethod private final Object handler; @Nullable private HandlerInterceptor[] interceptors; @Nullable private List<HandlerInterceptor> interceptorList; private int interceptorIndex = -1;}getHandler()
该办法遍历handlerMappings，匹配对应的HandlerMapping结构HandlerExecutionChain
@Nullable private List<HandlerMapping> handlerMappings; @Nullable protected HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception { if (this.handlerMappings != null) { for (HandlerMapping mapping : this.handlerMappings) { HandlerExecutionChain handler = mapping.getHandler(request); if (handler != null) { return handler; } } } return null; }HandlerMapping接口，决定申请与相应处理器（HandlerExecutionChain）的映射关系
public interface HandlerMapping { @Nullable HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception;}HandlerMapping的常见实现类有
getHandlerAdapter办法
持续看回doDispatch办法中通过handler获取handlerAdapter的实现
@Nullable private List<HandlerAdapter> handlerAdapters; protected HandlerAdapter getHandlerAdapter(Object handler) throws ServletException { if (this.handlerAdapters != null) { for (HandlerAdapter adapter : this.handlerAdapters) { if (adapter.supports(handler)) { return adapter; } } } }HandlerAdapter接口
public interface HandlerAdapter { // 判断以后适配器是否反对该处理器 boolean supports(Object handler); // 解决申请，返回ModelAndView @Nullable ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception; long getLastModified(HttpServletRequest request, Object handler);}常见实现类
其中RequestMappingHandlerAdapter#handle的实现
ServletWebRequest webRequest = new ServletWebRequest(request, response); try { WebDataBinderFactory binderFactory = getDataBinderFactory(handlerMethod); ModelFactory modelFactory = getModelFactory(handlerMethod, binderFactory); // 将HandlerMethod转化为ServletInvocableHandlerMethod ServletInvocableHandlerMethod invocableMethod = createInvocableHandlerMethod(handlerMethod); if (this.argumentResolvers != null) { invocableMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers); } if (this.returnValueHandlers != null) { invocableMethod.setHandlerMethodReturnValueHandlers(this.returnValueHandlers); } invocableMethod.setDataBinderFactory(binderFactory); invocableMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer); ModelAndViewContainer mavContainer = new ModelAndViewContainer(); mavContainer.addAllAttributes(RequestContextUtils.getInputFlashMap(request)); modelFactory.initModel(webRequest, mavContainer, invocableMethod); mavContainer.setIgnoreDefaultModelOnRedirect(this.ignoreDefaultModelOnRedirect); AsyncWebRequest asyncWebRequest = WebAsyncUtils.createAsyncWebRequest(request, response); asyncWebRequest.setTimeout(this.asyncRequestTimeout); WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request); asyncManager.setTaskExecutor(this.taskExecutor); asyncManager.setAsyncWebRequest(asyncWebRequest); asyncManager.registerCallableInterceptors(this.callableInterceptors); asyncManager.registerDeferredResultInterceptors(this.deferredResultInterceptors); if (asyncManager.hasConcurrentResult()) { Object result = asyncManager.getConcurrentResult(); mavContainer = (ModelAndViewContainer) asyncManager.getConcurrentResultContext()[0]; asyncManager.clearConcurrentResult(); LogFormatUtils.traceDebug(logger, traceOn -> { String formatted = LogFormatUtils.formatValue(result, !traceOn); return "Resume with async result [" + formatted + "]"; }); invocableMethod = invocableMethod.wrapConcurrentResult(result); } // 最终执行invokeAndHandle invocableMethod.invokeAndHandle(webRequest, mavContainer); if (asyncManager.isConcurrentHandlingStarted()) { return null; } return getModelAndView(mavContainer, modelFactory, webRequest); } finally { webRequest.requestCompleted(); }