# webpemo

**Repository Path**: nickdong/webpemo

## Basic Information

- **Project Name**: webpemo
- **Description**: No description available
- **Primary Language**: Java
- **License**: GPL-3.0
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2021-12-22
- **Last Updated**: 2021-12-22

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

servlet 用于处理请求
处理请求的核心文件

`spring-webmvc-5.3.13-sources.jar!/org/springframework/web/servlet/DispatcherServlet.java`
用于处理请求的方法
```java
	@SuppressWarnings("deprecation")
	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 = HttpMethod.GET.matches(method);
				if (isGet || HttpMethod.HEAD.matches(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);
				}
			}
		}
	}
```

### 扩展 Spring MVC
[spring boot 2.6.1 DOC web.servlet.spring-mvc.auto-configuration](https://docs.spring.io/spring-boot/docs/2.6.1/reference/html/web.html#web.servlet.spring-mvc.auto-configuration)



### 自定义 视图解析
`spring-webmvc-5.3.13-sources.jar!/org/springframework/web/servlet/ViewResolver.java`
`spring-webmvc-5.3.13-sources.jar!/org/springframework/web/servlet/view/ContentNegotiatingViewResolver.java`

```java
	public View resolveViewName(String viewName, Locale locale) throws Exception {
		RequestAttributes attrs = RequestContextHolder.getRequestAttributes();
		Assert.state(attrs instanceof ServletRequestAttributes, "No current ServletRequestAttributes");
		List<MediaType> requestedMediaTypes = getMediaTypes(((ServletRequestAttributes) attrs).getRequest());
		if (requestedMediaTypes != null) {
			List<View> candidateViews = getCandidateViews(viewName, locale, requestedMediaTypes);
			View bestView = getBestView(candidateViews, requestedMediaTypes, attrs);
			if (bestView != null) {
				return bestView;
			}
		}

		String mediaTypeInfo = logger.isDebugEnabled() && requestedMediaTypes != null ?
				" given " + requestedMediaTypes.toString() : "";

		if (this.useNotAcceptableStatusCode) {
			if (logger.isDebugEnabled()) {
				logger.debug("Using 406 NOT_ACCEPTABLE" + mediaTypeInfo);
			}
			return NOT_ACCEPTABLE_VIEW;
		}
		else {
			logger.debug("View remains unresolved" + mediaTypeInfo);
			return null;
		}
	}
```

```java
	private List<View> getCandidateViews(String viewName, Locale locale, List<MediaType> requestedMediaTypes)
			throws Exception {

		List<View> candidateViews = new ArrayList<>();
		if (this.viewResolvers != null) {
			Assert.state(this.contentNegotiationManager != null, "No ContentNegotiationManager set");
			for (ViewResolver viewResolver : this.viewResolvers) {
				View view = viewResolver.resolveViewName(viewName, locale);
				if (view != null) {
					candidateViews.add(view);
				}
				for (MediaType requestedMediaType : requestedMediaTypes) {
					List<String> extensions = this.contentNegotiationManager.resolveFileExtensions(requestedMediaType);
					for (String extension : extensions) {
						String viewNameWithExtension = viewName + '.' + extension;
						view = viewResolver.resolveViewName(viewNameWithExtension, locale);
						if (view != null) {
							candidateViews.add(view);
						}
					}
				}
			}
		}
		if (!CollectionUtils.isEmpty(this.defaultViews)) {
			candidateViews.addAll(this.defaultViews);
		}
		return candidateViews;
	}
```


### 使用 thymeleaf


### 自定义国际化处理 MyLocalResolver
源代码
`spring-webmvc-5.3.13-sources.jar!/org/springframework/web/servlet/i18n/AcceptHeaderLocaleResolver.java`

```java
public class AcceptHeaderLocaleResolver implements LocaleResolver {

    // ... ...
	@Override
	public Locale resolveLocale(HttpServletRequest request) {
		Locale defaultLocale = getDefaultLocale();
		if (defaultLocale != null && request.getHeader("Accept-Language") == null) {
			return defaultLocale;
		}
		Locale requestLocale = request.getLocale();
		List<Locale> supportedLocales = getSupportedLocales();
		if (supportedLocales.isEmpty() || supportedLocales.contains(requestLocale)) {
			return requestLocale;
		}
		Locale supportedLocale = findSupportedLocale(request, supportedLocales);
		if (supportedLocale != null) {
			return supportedLocale;
		}
		return (defaultLocale != null ? defaultLocale : requestLocale);
	}
    // ... ...
	@Override
	public void setLocale(HttpServletRequest request, @Nullable HttpServletResponse response, @Nullable Locale locale) {
		throw new UnsupportedOperationException(
				"Cannot change HTTP accept header - use a different locale resolution strategy");
	}

}
```