初步完成形式主义学习

spring-framework-main/spring-web/src/main/java/org/springframework/web/context/request/ServletWebRequest.java

@@ -208,6 +208,8 @@ public class ServletWebRequest extends ServletRequestAttributes implements Nativ
 	@Override
 	public boolean checkNotModified(@Nullable String etag, long lastModifiedTimestamp) {
 		HttpServletResponse response = getResponse();
+		// notModified 为 true 标志没有被修改，默认false
+		// 如果 notModified 已经 true || 返回状态码已经不是 200 直接返回 notModified
 		if (this.notModified || (response != null && HttpStatus.OK.value() != response.getStatus())) {
 			return this.notModified;
 		}
@@ -215,7 +217,9 @@ public class ServletWebRequest extends ServletRequestAttributes implements Nativ
 		// Evaluate conditions in order of precedence.
 		// See https://tools.ietf.org/html/rfc7232#section-6
 
+		// 解析校验 If-Unmodified-Since 请求头。这个请求头和  If-Modified-Since 请求头相反
 		if (validateIfUnmodifiedSince(lastModifiedTimestamp)) {
+			// 设置状态码 304，并返回 notModified
 			if (this.notModified && response != null) {
 				response.setStatus(HttpStatus.PRECONDITION_FAILED.value());
 			}
@@ -228,6 +232,7 @@ public class ServletWebRequest extends ServletRequestAttributes implements Nativ
 		}
 
 		// Update response
+		// 更新 Response。包括状态码等信息
 		if (response != null) {
 			boolean isHttpGetOrHead = SAFE_METHODS.contains(getRequest().getMethod());
 			if (this.notModified) {
@@ -306,6 +311,7 @@ public class ServletWebRequest extends ServletRequestAttributes implements Nativ
 		return "\"" + etag + "\"";
 	}
 
+	// 解析校验 If-Modified-Since 请求头
 	private boolean validateIfModifiedSince(long lastModifiedTimestamp) {
 		if (lastModifiedTimestamp < 0) {
 			return false;

spring-framework-main/spring-webmvc/src/main/java/org/springframework/web/servlet/FrameworkServlet.java

@@ -998,13 +998,19 @@ public abstract class FrameworkServlet extends HttpServletBean implements Applic
 	protected final void processRequest(HttpServletRequest request, HttpServletResponse response)
 			throws ServletException, IOException {
 
+		// 记录当前时间，用于记录web请求的记录时间
 		long startTime = System.currentTimeMillis();
 		Throwable failureCause = null;
 
+		// 1234 的目的是为了保证当前线程的 LocaleContext 和 RequestAttributes 在当前请求后还能恢复，所以提取保存
+		// 1 提取当前线程的 LocaleContext 属性
 		LocaleContext previousLocaleContext = LocaleContextHolder.getLocaleContext();
+		// 2. 根据当前的 request 创建对应的 LocaleContext，并绑定到当前线程
 		LocaleContext localeContext = buildLocaleContext(request);
 
+		// 3. 提取当前线程的 RequestAttributes 属性
 		RequestAttributes previousAttributes = RequestContextHolder.getRequestAttributes();
+		// 4. 根据当前的request 创建对应的 RequestAttributes ,并绑定到当前线程
 		ServletRequestAttributes requestAttributes = buildRequestAttributes(request, response, previousAttributes);
 
 		WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
@@ -1013,6 +1019,7 @@ public abstract class FrameworkServlet extends HttpServletBean implements Applic
 		initContextHolders(request, localeContext, requestAttributes);
 
 		try {
+			// 5. 委托给 doservice方法进行进一步处理
 			doService(request, response);
 		}
 		catch (ServletException | IOException ex) {
@@ -1025,11 +1032,13 @@ public abstract class FrameworkServlet extends HttpServletBean implements Applic
 		}
 
 		finally {
+			// 6. 请求结束，恢复线程原状
 			resetContextHolders(request, previousLocaleContext, previousAttributes);
 			if (requestAttributes != null) {
 				requestAttributes.requestCompleted();
 			}
 			logResult(request, response, failureCause, asyncManager);
+			// 发布请求结束的通知事件，无论成功与否
 			publishRequestHandledEvent(request, response, startTime, failureCause);
 		}
 	}

spring-framework-main/spring-webmvc/src/main/java/org/springframework/web/servlet/HandlerExecutionChain.java

@@ -144,6 +144,7 @@ public class HandlerExecutionChain {
 		for (int i = 0; i < this.interceptorList.size(); i++) {
 			HandlerInterceptor interceptor = this.interceptorList.get(i);
 			if (!interceptor.preHandle(request, response, this.handler)) {
+				// 调用前置方法。如果有一个前置方法返回false，则直接调用完成方法
 				triggerAfterCompletion(request, response, null);
 				return false;
 			}

spring-framework-main/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java

@@ -857,7 +857,9 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 			WebDataBinderFactory binderFactory = getDataBinderFactory(handlerMethod);
 			ModelFactory modelFactory = getModelFactory(handlerMethod, binderFactory);
 
+			// 将 handlerMethod 转换成 ServletInvocableHandlerMethod
 			ServletInvocableHandlerMethod invocableMethod = createInvocableHandlerMethod(handlerMethod);
+			// 设置ServletInvocableHandlerMethod  的一些属性
 			if (this.argumentResolvers != null) {
 				invocableMethod.setHandlerMethodArgumentResolvers(this.argumentResolvers);
 			}
@@ -868,6 +870,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 			invocableMethod.setParameterNameDiscoverer(this.parameterNameDiscoverer);
 
 			ModelAndViewContainer mavContainer = new ModelAndViewContainer();
+			// 创建 ModelAndView 容器，并设置一些属性
 			mavContainer.addAllAttributes(RequestContextUtils.getInputFlashMap(request));
 			modelFactory.initModel(webRequest, mavContainer, invocableMethod);
 			mavContainer.setIgnoreDefaultModelOnRedirect(this.ignoreDefaultModelOnRedirect);
@@ -892,11 +895,13 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 				invocableMethod = invocableMethod.wrapConcurrentResult(result);
 			}
 
+			// 反射调用 HandlerMethod
 			invocableMethod.invokeAndHandle(webRequest, mavContainer);
 			if (asyncManager.isConcurrentHandlingStarted()) {
 				return null;
 			}
 
+			// 封装成 ModelAndView
 			return getModelAndView(mavContainer, modelFactory, webRequest);
 		}
 		finally {

spring-framework-main/spring-webmvc/src/main/java/org/springframework/web/servlet/view/AbstractCachingViewResolver.java

@@ -170,10 +170,12 @@ public abstract class AbstractCachingViewResolver extends WebApplicationObjectSu
 	@Override
 	@Nullable
 	public View resolveViewName(String viewName, Locale locale) throws Exception {
+		// 如果没有缓存，则直接创建 View
 		if (!isCache()) {
 			return createView(viewName, locale);
 		}
 		else {
+			// 从缓存中获取视图
 			Object cacheKey = getCacheKey(viewName, locale);
 			View view = this.viewAccessCache.get(cacheKey);
 			if (view == null) {

spring-framework-main/spring-webmvc/src/main/java/org/springframework/web/servlet/view/AbstractView.java

@@ -309,8 +309,11 @@ public abstract class AbstractView extends WebApplicationObjectSupport implement
 					(this.staticAttributes.isEmpty() ? "" : ", static attributes " + this.staticAttributes));
 		}
 
+		// 将要用到的属性放入到 mergedModel  中
 		Map<String, Object> mergedModel = createMergedOutputModel(model, request, response);
+		// 准备 Response
 		prepareResponse(request, response);
+		// 处理页面跳转。同时将 mergedModel 保存到 request 中
 		renderMergedOutputModel(mergedModel, getRequestToExpose(request), response);
 	}
 

spring-framework-main/spring-webmvc/src/main/java/org/springframework/web/servlet/view/UrlBasedViewResolver.java

@@ -464,11 +464,13 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 	protected View createView(String viewName, Locale locale) throws Exception {
 		// If this resolver is not supposed to handle the given view,
 		// return null to pass on to the next resolver in the chain.
+		// 如果当前视图解析器无法解析该视图，则返回null
 		if (!canHandle(viewName, locale)) {
 			return null;
 		}
 
 		// Check for special "redirect:" prefix.
+		// 处理前缀为  "redirect:" (重定向)的情况
 		if (viewName.startsWith(REDIRECT_URL_PREFIX)) {
 			String redirectUrl = viewName.substring(REDIRECT_URL_PREFIX.length());
 			RedirectView view = new RedirectView(redirectUrl,
@@ -481,6 +483,7 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 		}
 
 		// Check for special "forward:" prefix.
+		// 处理前缀为  "forward:" 的情况
 		if (viewName.startsWith(FORWARD_URL_PREFIX)) {
 			String forwardUrl = viewName.substring(FORWARD_URL_PREFIX.length());
 			InternalResourceView view = new InternalResourceView(forwardUrl);
@@ -488,6 +491,7 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 		}
 
 		// Else fall back to superclass implementation: calling loadView.
+		// 调用父类的方法创建视图
 		return super.createView(viewName, locale);
 	}
 
@@ -567,6 +571,7 @@ public class UrlBasedViewResolver extends AbstractCachingViewResolver implements
 	 */
 	protected AbstractUrlBasedView buildView(String viewName) throws Exception {
 		AbstractUrlBasedView view = instantiateView();
+		// 设置视图 url 添加前缀和后缀
 		view.setUrl(getPrefix() + viewName + getSuffix());
 		view.setAttributesMap(getAttributesMap());