SpringMVCはリクエストからの解析済みビューをどのように配布するのですか?
最初にSpringMVCの9つの主要コンポーネントを理解する
// 文件解析
/** MultipartResolver used by this servlet. */
@Nullable
private MultipartResolver multipartResolver;
// 国际化解析
/** LocaleResolver used by this servlet. */
@Nullable
private LocaleResolver localeResolver;
// 主题解析器
/** ThemeResolver used by this servlet. */
@Nullable
private ThemeResolver themeResolver;
// 映射表
/** List of HandlerMappings used by this servlet. */
@Nullable
private List<HandlerMapping> handlerMappings;
// 适配器表
/** List of HandlerAdapters used by this servlet. */
@Nullable
private List<HandlerAdapter> handlerAdapters;
// 异常处理
/** List of HandlerExceptionResolvers used by this servlet. */
@Nullable
private List<HandlerExceptionResolver> handlerExceptionResolvers;
//请求转视图名
/** RequestToViewNameTranslator used by this servlet. */
@Nullable
private RequestToViewNameTranslator viewNameTranslator;
// 重定向数据
/** FlashMapManager used by this servlet. */
@Nullable
private FlashMapManager flashMapManager;
// 视图解析器
/** List of ViewResolvers used by this servlet. */
@Nullable
private List<ViewResolver> viewResolvers;
1. htttpリクエストを受信する
2.フィルタリングリクエストには、一連のフィルタリングが含まれています。一般にdofilterメソッドです。
3. DispatchSerlet.classを使用してリクエストを処理する(コアクラス)
4. handleMappingsを使用して、リクエストに従って処理する必要があるコントローラーとターゲットメソッドを見つけます。
// Determine handler for the current request.
mappedHandler = getHandler(processedRequest);
それを見つける方法は?
@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;
}
すべてのHandlerMappingをトラバースするのは簡単です
HandlerMappingを初期化するプロセスで、少なくとも1つのhandlerMappingがあります
// handlerMappings的初始化
private void initHandlerMappings(ApplicationContext context) {
this.handlerMappings = null;
if (this.detectAllHandlerMappings) {
// Find all HandlerMappings in the ApplicationContext, including ancestor contexts.
Map<String, HandlerMapping> matchingBeans =
BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerMapping.class, true, false);
if (!matchingBeans.isEmpty()) {
this.handlerMappings = new ArrayList<>(matchingBeans.values());
// We keep HandlerMappings in sorted order.
AnnotationAwareOrderComparator.sort(this.handlerMappings);
}
}
else {
try {
HandlerMapping hm = context.getBean(HANDLER_MAPPING_BEAN_NAME, HandlerMapping.class);
this.handlerMappings = Collections.singletonList(hm);
}
catch (NoSuchBeanDefinitionException ex) {
// Ignore, we'll add a default HandlerMapping later.
}
}
// Ensure we have at least one HandlerMapping, by registering
// a default HandlerMapping if no other mappings are found.
if (this.handlerMappings == null) {
this.handlerMappings = getDefaultStrategies(context, HandlerMapping.class);
if (logger.isTraceEnabled()) {
logger.trace("No HandlerMappings declared for servlet '" + getServletName() +
"': using default strategies from DispatcherServlet.properties");
}
}
}
5.ハンドラーに応じて適切なhandlerAdapterを選択します
// Determine handler adapter for the current request.
HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler());
6.ターゲットメソッドを実行し、ModelAndViewを生成します。
アダプター
mv = ha.handle(processedRequest, response, mappedHandler.getHandler());
POJOをテストします。文字列型には実際には戻り値しかないため、現時点ではmav = null;
7. ModelAndViewに従って結果を返す
レンダービューを表示し、そうでない場合はビューのロードをスキップします
processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException);
フローチャートは以下の通りです
DispatcherServletコアメソッド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 {
// 是否为文件上传
processedRequest = checkMultipart(request);
multipartRequestParsed = (processedRequest != request);
// 找到处理这个请求的Controller
// Determine handler for the current request.
mappedHandler = getHandler(processedRequest);
// 没有找到处理的Controller准备返回
if (mappedHandler == null) {
noHandlerFound(processedRequest, response);
return;
}
// 处理适配器
// 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;
}
// 生成ModelAndView (最最最核心的部分)
// 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);
}
// 渲染ModelAndView 到页面
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);
}
}
}
}
その結果
明らかにSpringMVCはアダプターモード
異なる方法に従って異なるクラスを選択する