做华为网站的还有哪些功能,网站建设对企业经营,重庆百科网站推广,大型网站开发软件目录 一、HttpMessageConverter1、RequestBody2、RequestEntity3、ResponseBody4、SpringMVC处理json5、SpringMVC处理ajax6、RestController注解7、ResponseEntity7.1、文件下载7.2、文件上传 二、拦截器1、拦截器的配置2、拦截器的三个抽象方法3、多个拦截器的执行顺序 三、异… 目录 一、HttpMessageConverter1、RequestBody2、RequestEntity3、ResponseBody4、SpringMVC处理json5、SpringMVC处理ajax6、RestController注解7、ResponseEntity7.1、文件下载7.2、文件上传 二、拦截器1、拦截器的配置2、拦截器的三个抽象方法3、多个拦截器的执行顺序 三、异常处理器1、基于配置的异常处理2、基于注解的异常处理 四、注解配置SpringMVC1、创建初始化类代替web.xml2、创建SpringConfig配置类代替spring的配置文件3、创建WebConfig配置类代替SpringMVC的配置文件4、测试功能 五、SpringMVC执行流程1、SpringMVC常用组件2、DispatcherServlet初始化过程3、DispatcherServlet调用组件处理请求4、SpringMVC的执行流程 一、HttpMessageConverter
HttpMessageConverter 报文信息转换器将请求报文转换为Java对象或将Java对象转换为响应报文 HttpMessageConverter提供了两个注解和两个类型 RequestBody ResponseBody RequestEntity ResponseEntity
1、RequestBody
RequestBody 可以获取请求体需要在控制器方法设置一个形参使用 RequestBody 进行标识当前请求的请求体就会为当前注解所标识的形参赋值
form th:action{/testRequestBody} methodpost 用户名input typetext nameusernamebr 密码input typepassword namepasswordbr input typesubmit
/formRequestMapping(/testRequestBody)
public String testRequestBody(RequestBody String requestBody){System.out.println(requestBody:requestBody); return success;
}输出结果requestBody:usernameadminpassword123456
2、RequestEntity
RequestEntity 封装请求报文的一种类型需要在控制器方法的形参中设置该类型的形参当前请求的请求报文就会赋值给该形参可以通过getHeaders() 获取请求头信息通过 getBody() 获取请求体信息
RequestMapping(/testRequestEntity)
public String testRequestEntity(RequestEntityString requestEntity){System.out.println(requestHeader:requestEntity.getHeaders());System.out.println(requestBody:requestEntity.getBody()); return success;
}输出结果 requestHeader:[host:“localhost:8080”, connection:“keep-alive”, content-length:“27”, cache-control:“max-age0”, sec-ch-ua:“” Not A;Brand;v“99”, “Chromium”;v“90”, “Google Chrome”;v“90”, sec-ch-ua-mobile:“?0”, upgrade-insecure-requests:“1”, origin: http://localhost:8 080 , user-agent:“Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.93 Safari/537.36”] requestBody:usernameadminpassword123
3、ResponseBody
ResponseBody 用于标识一个控制器方法可以将该方法的返回值直接作为响应报文的响应体响应到浏览器
RequestMapping(/testResponseBody)
ResponseBody
public String testResponseBody(){ return success;
}结果浏览器页面显示success
4、SpringMVC处理json
ResponseBody处理json的步骤 导入jackson的依赖 !--导入jackson的依赖--dependencygroupIdcom.fasterxml.jackson.core/groupIdartifactIdjackson-databind/artifactIdversion2.12.1/version/dependency在 SpringMVC 的核心配置文件中开启 mvc 的注解驱动此时在 HandlerAdaptor 中会自动装配一个消息转换器MappingJackson2HttpMessageConverter 可以将响应到浏览器的 Java 对象转换为 Json 格式的字符串 !--开启注解驱动--mvc:annotation-driven /在处理器方法上使用 ResponseBody 注解进行标识 将 Java 对象直接作为控制器方法的返回值返回就会自动转换为 Json 格式的字符串 RequestMapping(/testResponseUser)
ResponseBody
public User testResponseUser(){ return new User(1001,admin,123456,23,男);
}浏览器的页面中展示的结果 {“id”:1001,“username”:“admin”,“password”:“123456”,“age”:23,“sex”:“男”}
5、SpringMVC处理ajax 请求超链接 div idappa th:href{/testAjax} clicktestAjaxtestAjax/abr
/div通过vue和axios处理点击事件 script typetext/javascript th:src{/static/js/vue.js}/script
script typetext/javascript th:src{/static/js/axios.min.js}/script
script typetext/javascript var vue new Vue({ el:#app, methods:{ testAjax:function (event) { axios({ method:post, url:event.target.href, params:{ username:admin, password:123456 } }).then(function (response) { alert(response.data); });event.preventDefault(); } } });
/script控制器方法 RequestMapping(/testAjax)
ResponseBody
public String testAjax(String username, String password){System.out.println(username:username,password:password); return hello,ajax;
}6、RestController注解
RestController 注解是 springMVC 提供的一个复合注解标识在控制器的类上就相当于为类添加了Controller注解并且为其中的每个方法添加了 ResponseBody 注解
7、ResponseEntity
ResponseEntity用于控制器方法的返回值类型 该控制器方法的返回值就是响应到浏览器的响应报文
7.1、文件下载
使用ResponseEntity实现下载文件的功能
!DOCTYPE html
html langen xmlns:thhttp://www.thymeleaf.org
headmeta charsetUTF-8title测试文件上传和下载/title
/head
body
a th:href{/testDown}下载1.jpeg/a
br
form th:action{/testUp} methodpost enctypemultipart/form-data头像input typefile namephoto/brinput typesubmit value上传/
/form
/body
/htmlRequestMapping(value /testDown,method RequestMethod.GET)public ResponseEntitybyte[] testResponseEntity(HttpSession session) throws IOException {//获取ServletContext对象ServletContext servletContext session.getServletContext();//获取服务器中文件的真实路径String realPath servletContext.getRealPath(/static/img/1.jpeg);//创建输入流InputStream is new FileInputStream(realPath);//创建字节数组byte[] bytes new byte[is.available()];//将流读到字节数组中is.read(bytes);//创建HttpHeaders对象设置响应头信息MultiValueMapString,String headers new HttpHeaders();headers.add(Content-Disposition,attachment;filename1.jpeg);//设置响应状态码HttpStatus statusCode HttpStatus.OK;//创建ResponseEntity对象ResponseEntitybyte[] responseEntity new ResponseEntity(bytes,headers,statusCode);//关闭输入流is.close();return responseEntity;}7.2、文件上传
文件上传要求 form 表单的请求方式必须为 post 并且添加属性 enctypemultipart/form-dataSpringMVC 中将上传的文件封装到 MultipartFile 对象中通过此对象可以获取文件相关信息 上传步骤 添加依赖 !-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload --
dependency groupIdcommons-fileupload/groupId artifactIdcommons-fileupload/artifactId version1.3.1/version
/dependency在SpringMVC的配置文件中添加配置 !--必须通过文件解析器的解析才能将文件转换为MultipartFile对象--bean idmultipartResolver classorg.springframework.web.multipart.commons.CommonsMultipartResolver/bean控制器方法 RequestMapping(value /testUp,method RequestMethod.POST)public String testUp(MultipartFile photo,HttpSession session) throws IOException {//获取上传的文件的文件名String fileName photo.getOriginalFilename();//处理文件重名问题String hzName fileName.substring(fileName.lastIndexOf(.));fileName UUID.randomUUID().toString() hzName;//获取服务器中photo目录的路径ServletContext servletContext session.getServletContext();String photoPath servletContext.getRealPath(photo);File file new File(photoPath);if(!file.exists()){file.mkdir();}String finalPath photoPath File.separator fileName;//实现上传功能photo.transferTo(new File(finalPath));return success;}二、拦截器
1、拦截器的配置
SpringMVC 中的拦截器用于拦截控制器方法的执行 SpringMVC 中的拦截器需要实现 HandlerInterceptor SpringMVC 的拦截器必须在 SpringMVC 的配置文件中进行配置
mvc:interceptorsbean classcom.zhao.interceptor.FirstInterceptor/beanref beanfirstInterceptor/ref!-- 以上两种配置方式都是对DispatcherServlet所处理的所有的请求进行拦截 --mvc:interceptormvc:mapping path/**/mvc:exclude-mapping path/testRequestEntity/ref beanfirstInterceptor/ref/mvc:interceptor!--以上配置方式可以通过ref或bean标签设置拦截器通过mvc:mapping设置需要拦截的请求通过 mvc:exclude-mapping设置需要排除的请求即不需要拦截的请求--
/mvc:interceptor2、拦截器的三个抽象方法
SpringMVC 中的拦截器有三个抽象方法
preHandle 控制器方法执行之前执行 preHandle() 其 boolean 类型的返回值表示是否拦截或放行返回true 为放行即调用控制器方法返回 false 表示拦截即不调用控制器方法postHandle 控制器方法执行之后执行 postHandle()afterComplation 处理完视图和模型数据渲染视图完毕之后执行afterComplation()
3、多个拦截器的执行顺序
若每个拦截器的 preHandle() 都返回 true 此时多个拦截器的执行顺序和拦截器在 SpringMVC 的配置文件的配置顺序有关preHandle() 会按照配置的顺序执行而 postHandle() 和 afterComplation() 会按照配置的反序执行若某个拦截器的 preHandle() 返回了 false preHandle() 返回 false 和它之前的拦截器的 preHandle() 都会执行 postHandle() 都不执行返回 false的拦截器之前的拦截器的afterComplation() 会执行
三、异常处理器
1、基于配置的异常处理
SpringMVC 提供了一个处理控制器方法执行过程中所出现的异常的接口 HandlerExceptionResolver HandlerExceptionResolver 接口的实现类有DefaultHandlerExceptionResolver 和 SimpleMappingExceptionResolver SpringMVC 提供了自定义的异常处理器 SimpleMappingExceptionResolver 使用方式
bean classorg.springframework.web.servlet.handler.SimpleMappingExceptionResolver property nameexceptionMappings props !--properties的键表示处理器方法执行过程中出现的异常 properties的值表示若出现指定异常时设置一个新的视图名称跳转到指定页面 -- prop keyjava.lang.ArithmeticExceptionerror/prop /props /property !--exceptionAttribute属性设置一个属性名将出现的异常信息在请求域中进行共享 以value的值为键以异常为值-- property nameexceptionAttribute valueex/property /bean2、基于注解的异常处理
//ControllerAdvice将当前类标识为异常处理的组件
ControllerAdvice
public class ExceptionController { //ExceptionHandler用于设置所标识方法处理的异常 ExceptionHandler(ArithmeticException.class) //ex表示当前请求处理中出现的异常对象 public String handleArithmeticException(Exception ex, Model model){model.addAttribute(ex, ex);return error; }
}四、注解配置SpringMVC
使用配置类和注解代替web.xml和SpringMVC配置文件的功能
1、创建初始化类代替web.xml
在 Servlet3.0 环境中容器会在类路径中查找实现 javax.servlet.ServletContainerInitializer 接口的类如果找到的话就用它来配置Servlet 容器。 Spring 提供了这个接口的实现名为 SpringServletContainerInitializer 这个类反过来又会查找实现 WebApplicationInitializer 的类并将配置的任务交给它们来完成。Spring3.2 引入了一个便利的 WebApplicationInitializer 基础实现名为AbstractAnnotationConfigDispatcherServletInitializer当我们的类扩展了 AbstractAnnotationConfigDispatcherServletInitializer 并将其部署到 Servlet3.0 容器的时候容器会自动发现它并用它来配置Servlet 上下文
//web工程的初始化类用来代替web.xml
public class WebInit extends AbstractAnnotationConfigDispatcherServletInitializer {/*** 指定spring的配置类* return*/Overrideprotected Class?[] getRootConfigClasses() {return new Class[]{SpringConfig.class};}/*** 指定springMVC的配置类* return*/Overrideprotected Class?[] getServletConfigClasses() {return new Class[]{WebConfig.class};}/*** 指定DispatcherServlet的映射规则即url-pattern* return*/Overrideprotected String[] getServletMappings() {return new String[]{/};}/*** 注册过滤器* return*/Overrideprotected Filter[] getServletFilters() {CharacterEncodingFilter characterEncodingFilter new CharacterEncodingFilter();characterEncodingFilter.setEncoding(UTF-8);characterEncodingFilter.setForceResponseEncoding(true);HiddenHttpMethodFilter hiddenHttpMethodFilter new HiddenHttpMethodFilter();return new Filter[]{characterEncodingFilter, hiddenHttpMethodFilter};}
}2、创建SpringConfig配置类代替spring的配置文件
Configuration
public class SpringConfig {
//ssm整合之后spring的配置信息写在此类中
}3、创建WebConfig配置类代替SpringMVC的配置文件
/*** 代替SpringMVC的配置文件* 1、扫描组件 2、视图解析器 3、view-controller 4、default-servlet-handler* 5、mvc注解驱动 6、文件上传解析器 7、异常处理 8、拦截器*/
//将当前类标识为一个配置类
Configuration
//1、扫描组件
ComponentScan(com.atguigu.mvc.controller)
//5、mvc注解驱动
EnableWebMvc
public class WebConfig implements WebMvcConfigurer {//4、default-servlet-handlerOverridepublic void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {configurer.enable();}//8、拦截器Overridepublic void addInterceptors(InterceptorRegistry registry) {TestInterceptor testInterceptor new TestInterceptor();registry.addInterceptor(testInterceptor).addPathPatterns(/**);}//3、view-controllerOverridepublic void addViewControllers(ViewControllerRegistry registry) {registry.addViewController(/hello).setViewName(hello);}//6、文件上传解析器Beanpublic MultipartResolver multipartResolver(){CommonsMultipartResolver commonsMultipartResolver new CommonsMultipartResolver();return commonsMultipartResolver;}//7、异常处理Overridepublic void configureHandlerExceptionResolvers(ListHandlerExceptionResolver resolvers) {SimpleMappingExceptionResolver exceptionResolver new SimpleMappingExceptionResolver();Properties prop new Properties();prop.setProperty(java.lang.ArithmeticException, error);exceptionResolver.setExceptionMappings(prop);exceptionResolver.setExceptionAttribute(exception);resolvers.add(exceptionResolver);}//配置生成模板解析器Beanpublic ITemplateResolver templateResolver() {WebApplicationContext webApplicationContext ContextLoader.getCurrentWebApplicationContext();// ServletContextTemplateResolver需要一个ServletContext作为构造参数可通过WebApplicationContext 的方法获得ServletContextTemplateResolver templateResolver new ServletContextTemplateResolver(webApplicationContext.getServletContext());templateResolver.setPrefix(/WEB-INF/templates/);templateResolver.setSuffix(.html);templateResolver.setCharacterEncoding(UTF-8);templateResolver.setTemplateMode(TemplateMode.HTML);return templateResolver;}//生成模板引擎并为模板引擎注入模板解析器Beanpublic SpringTemplateEngine templateEngine(ITemplateResolver templateResolver) {SpringTemplateEngine templateEngine new SpringTemplateEngine();templateEngine.setTemplateResolver(templateResolver);return templateEngine;}//生成视图解析器并未解析器注入模板引擎Beanpublic ViewResolver viewResolver(SpringTemplateEngine templateEngine) {ThymeleafViewResolver viewResolver new ThymeleafViewResolver();viewResolver.setCharacterEncoding(UTF-8);viewResolver.setTemplateEngine(templateEngine);return viewResolver;}}4、测试功能
RequestMapping(/)
public String index(){ return index;
}五、SpringMVC执行流程
1、SpringMVC常用组件
DispatcherServlet前端控制器不需要工程师开发由框架提供 作用统一处理请求和响应整个流程控制的中心由它调用其它组件处理用户的请求 HandlerMapping 处理器映射器 不需要工程师开发由框架提供 作用根据请求的 url 、 method 等信息查找 Handler 即控制器方法 Handler 处理器 需要工程师开发 作用在 DispatcherServlet 的控制下 Handler 对具体的用户请求进行处理 HandlerAdapter 处理器适配器 不需要工程师开发由框架提供 作用通过 HandlerAdapter 对处理器控制器方法进行执行 ViewResolver 视图解析器 不需要工程师开发由框架提供 作用进行视图解析得到相应的视图例如ThymeleafView、InternalResourceView、RedirectView View 视图 作用将模型数据通过页面展示给用户
2、DispatcherServlet初始化过程
DispatcherServlet 本质上是一个 Servlet 所以天然的遵循 Servlet 的生命周期。所以宏观上是 Servlet生命周期来进行调度
初始化WebApplicationContext 所在类org.springframework.web.servlet.FrameworkServlet
protected WebApplicationContext initWebApplicationContext() {WebApplicationContext rootContext WebApplicationContextUtils.getWebApplicationContext(this.getServletContext());WebApplicationContext wac null;if (this.webApplicationContext ! null) {// A context instance was injected at construction time - use itwac this.webApplicationContext;if (wac instanceof ConfigurableWebApplicationContext) {ConfigurableWebApplicationContext cwac (ConfigurableWebApplicationContext)wac;if (!cwac.isActive()) {// The context has not yet been refreshed - provide services such as // setting the parent context, setting the application context id, etcif (cwac.getParent() null) {// The context instance was injected without an explicit parent - set // the root application context (if any; may be null) as the parentcwac.setParent(rootContext);}this.configureAndRefreshWebApplicationContext(cwac);}}}if (wac null) {// No context instance was injected at construction time - see if one // has been registered in the servlet context. If one exists, it is assumed // that the parent context (if any) has already been set and that the // user has performed any initialization such as setting the context idwac this.findWebApplicationContext();}if (wac null) {// No context instance is defined for this servlet - create a local one // 创建WebApplicationContextwac this.createWebApplicationContext(rootContext);}if (!this.refreshEventReceived) {// Either the context is not a ConfigurableApplicationContext with refresh // support or the context injected at construction time had already been // refreshed - trigger initial onRefresh manually here.synchronized(this.onRefreshMonitor) {// 刷新WebApplicationContextthis.onRefresh(wac);}}if (this.publishContext) {// Publish the context as a servlet context attribute. // 将IOC容器在应用域共享String attrName this.getServletContextAttributeName();this.getServletContext().setAttribute(attrName, wac);}return wac;}创建WebApplicationContext 所在类org.springframework.web.servlet.FrameworkServlet
protected WebApplicationContext createWebApplicationContext(Nullable ApplicationContext parent) {Class? contextClass this.getContextClass();if (!ConfigurableWebApplicationContext.class.isAssignableFrom(contextClass)) {throw new ApplicationContextException(Fatal initialization error in servlet with name this.getServletName() : custom WebApplicationContext class [ contextClass.getName() ] is not of type ConfigurableWebApplicationContext);} else {// 通过反射创建 IOC 容器对象ConfigurableWebApplicationContext wac (ConfigurableWebApplicationContext)BeanUtils.instantiateClass(contextClass);wac.setEnvironment(this.getEnvironment());// 设置父容器wac.setParent(parent);String configLocation this.getContextConfigLocation();if (configLocation ! null) {wac.setConfigLocation(configLocation);}this.configureAndRefreshWebApplicationContext(wac);return wac;}}DispatcherServlet初始化策略 FrameworkServlet 创建 WebApplicationContext 后刷新容器调用 onRefresh(wac) 此方法在 DispatcherServlet 中进行了重写调用了 initStrategies(context) 方法初始化策略即初始化 DispatcherServlet 的各个组件 所在类org.springframework.web.servlet.DispatcherServlet
protected void initStrategies(ApplicationContext context) { initMultipartResolver(context); initLocaleResolver(context); initThemeResolver(context); initHandlerMappings(context);initHandlerAdapters(context); initHandlerExceptionResolvers(context); initRequestToViewNameTranslator(context); initViewResolvers(context); initFlashMapManager(context);
}3、DispatcherServlet调用组件处理请求 processRequest() FrameworkServlet 重写 HttpServlet 中的 service() 和 doXxx() 这些方法中调用了 processRequest(request, response)
所在类 org.springframework.web.servlet.FrameworkServlet
protected final void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {long startTime System.currentTimeMillis();Throwable failureCause null;LocaleContext previousLocaleContext LocaleContextHolder.getLocaleContext();LocaleContext localeContext this.buildLocaleContext(request);RequestAttributes previousAttributes RequestContextHolder.getRequestAttributes();ServletRequestAttributes requestAttributes this.buildRequestAttributes(request, response, previousAttributes);WebAsyncManager asyncManager WebAsyncUtils.getAsyncManager(request);asyncManager.registerCallableInterceptor(FrameworkServlet.class.getName(), new FrameworkServlet.RequestBindingInterceptor());this.initContextHolders(request, localeContext, requestAttributes);try {// 执行服务doService()是一个抽象方法在DispatcherServlet中进行了重写this.doService(request, response);} catch (IOException | ServletException var16) {failureCause var16;throw var16;} catch (Throwable var17) {failureCause var17;throw new NestedServletException(Request processing failed, var17);} finally {this.resetContextHolders(request, previousLocaleContext, previousAttributes);if (requestAttributes ! null) {requestAttributes.requestCompleted();}this.logResult(request, response, (Throwable)failureCause, asyncManager);this.publishRequestHandledEvent(request, response, startTime, (Throwable)failureCause);}}doService() 所在类org.springframework.web.servlet.DispatcherServlet protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception {this.logRequest(request);// Keep a snapshot of the request attributes in case of an include, // to be able to restore the original attributes after the include.MapString, Object attributesSnapshot null;if (WebUtils.isIncludeRequest(request)) {attributesSnapshot new HashMap();Enumeration attrNames request.getAttributeNames();label120:while(true) {String attrName;do {if (!attrNames.hasMoreElements()) {break label120;}attrName (String)attrNames.nextElement();} while(!this.cleanupAfterInclude !attrName.startsWith(org.springframework.web.servlet));attributesSnapshot.put(attrName, request.getAttribute(attrName));}}// Make framework objects available to handlers and view objects.request.setAttribute(WEB_APPLICATION_CONTEXT_ATTRIBUTE, this.getWebApplicationContext());request.setAttribute(LOCALE_RESOLVER_ATTRIBUTE, this.localeResolver);request.setAttribute(THEME_RESOLVER_ATTRIBUTE, this.themeResolver);request.setAttribute(THEME_SOURCE_ATTRIBUTE, this.getThemeSource());if (this.flashMapManager ! null) {FlashMap inputFlashMap this.flashMapManager.retrieveAndUpdate(request, response);if (inputFlashMap ! null) {request.setAttribute(INPUT_FLASH_MAP_ATTRIBUTE, Collections.unmodifiableMap(inputFlashMap));}request.setAttribute(OUTPUT_FLASH_MAP_ATTRIBUTE, new FlashMap());request.setAttribute(FLASH_MAP_MANAGER_ATTRIBUTE, this.flashMapManager);}RequestPath requestPath null;if (this.parseRequestPath !ServletRequestPathUtils.hasParsedRequestPath(request)) {requestPath ServletRequestPathUtils.parseAndCache(request);}try {// 处理请求和响应this.doDispatch(request, response);} finally {// Restore the original attribute snapshot, in case of an include.if (!WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted() attributesSnapshot ! null) {this.restoreAttributesAfterInclude(request, attributesSnapshot);}if (requestPath ! null) {ServletRequestPathUtils.clearParsedRequestPath(request);}}}doDispatch() 所在类org.springframework.web.servlet.DispatcherServlet protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception {HttpServletRequest processedRequest request;HandlerExecutionChain mappedHandler null;boolean multipartRequestParsed false;WebAsyncManager asyncManager WebAsyncUtils.getAsyncManager(request);try {try {ModelAndView mv null;Object dispatchException null;try {processedRequest this.checkMultipart(request);multipartRequestParsed processedRequest ! request;// Determine handler for the current request. /* mappedHandler调用链 包含handler、interceptorList、interceptorIndex handler浏览器发送的请求所匹配的控制器方法 interceptorList处理控制器方法的所有拦截器集合 interceptorIndex拦截器索引控制拦截器afterCompletion()的执行 */mappedHandler this.getHandler(processedRequest);if (mappedHandler null) {this.noHandlerFound(processedRequest, response);return;}// Determine handler adapter for the current request. // 通过控制器方法创建相应的处理器适配器调用所对应的控制器方法HandlerAdapter ha this.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;}}// 调用拦截器的preHandle()if (!mappedHandler.applyPreHandle(processedRequest, response)) {return;}// Actually invoke the handler. // 由处理器适配器调用具体的控制器方法最终获得ModelAndView对象mv ha.handle(processedRequest, response, mappedHandler.getHandler());if (asyncManager.isConcurrentHandlingStarted()) {return;}this.applyDefaultViewName(processedRequest, mv);// 调用拦截器的postHandle()mappedHandler.applyPostHandle(processedRequest, response, mv);} catch (Exception var20) {dispatchException var20;} catch (Throwable var21) {// As of 4.3, were processing Errors thrown from handler methods as well, // making them available for ExceptionHandler methods and other scenarios.dispatchException new NestedServletException(Handler dispatch failed, var21);}// 后续处理处理模型数据和渲染视图this.processDispatchResult(processedRequest, response, mappedHandler, mv, (Exception)dispatchException);} catch (Exception var22) {this.triggerAfterCompletion(processedRequest, response, mappedHandler, var22);} catch (Throwable var23) {this.triggerAfterCompletion(processedRequest, response, mappedHandler, new NestedServletException(Handler processing failed, var23));}} finally {if (asyncManager.isConcurrentHandlingStarted()) {// Instead of postHandle and afterCompletionif (mappedHandler ! null) {mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);}// Clean up any resources used by a multipart request.} else if (multipartRequestParsed) {this.cleanupMultipart(processedRequest);}}}processDispatchResult() private void processDispatchResult(HttpServletRequest request, HttpServletResponse response, Nullable HandlerExecutionChain mappedHandler, Nullable ModelAndView mv, Nullable Exception exception) throws Exception {boolean errorView false;if (exception ! null) {if (exception instanceof ModelAndViewDefiningException) {this.logger.debug(ModelAndViewDefiningException encountered, exception);mv ((ModelAndViewDefiningException)exception).getModelAndView();} else {Object handler mappedHandler ! null ? mappedHandler.getHandler() : null;mv this.processHandlerException(request, response, handler, exception);errorView mv ! null;}}// Did the handler return a view to render?if (mv ! null !mv.wasCleared()) {// 处理模型数据和渲染视图this.render(mv, request, response);if (errorView) {WebUtils.clearErrorRequestAttributes(request);}} else if (this.logger.isTraceEnabled()) {this.logger.trace(No view rendering, null ModelAndView returned.);}// Concurrent handling started during a forwardif (!WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) {if (mappedHandler ! null) {// Exception (if any) is already handled.. // 调用拦截器的afterCompletion()mappedHandler.triggerAfterCompletion(request, response, (Exception)null);}}}4、SpringMVC的执行流程
用户向服务器发送请求请求被 SpringMVC 前端控制器 DispatcherServlet 捕获。DispatcherServlet 对请求 URL 进行解析得到请求资源标识符 URI 判断请求 URI 对应的映射 不存在 再判断是否配置了 mvc:default-servlet-handler 如果没配置则控制台报映射查找不到客户端展示 404 错误 如果有配置则访问目标资源一般为静态资源如 JS,CSS,HTML 找不到客户端也会展示 404错误 存在则执行下面的流程
根据该 URI 调用 HandlerMapping 获得该 Handler 配置的所有相关的对象包括 Handler 对象以及Handler对象对应的拦截器最后以 HandlerExecutionChain 执行链对象的形式返回DispatcherServlet 根据获得的 Handler 选择一个合适的 HandlerAdapter如果成功获得 HandlerAdapter 此时将开始执行拦截器的 preHandler(…) 方法【正向】提取 Request 中的模型数据填充 Handler 入参开始执行 Handler Controller) 方法处理请求。在填充 Handler 的入参过程中根据你的配置 Spring 将帮你做一些额外的工作 HttpMessageConveter 将请求消息如 Json 、 xml 等数据转换成一个对象将对象转换为指定的响应信息数据转换对请求消息进行数据转换。如 String 转换成 Integer 、 Double 等数据格式化对请求消息进行数据格式化。 如将字符串转换成格式化数字或格式化日期等数据验证 验证数据的有效性长度、格式等验证结果存储到 BindingResult 或 Error 中 Handler 执行完成后向 DispatcherServlet 返回一个 ModelAndView 对象此时将开始执行拦截器的 postHandle(…) 方法【逆向】根据返回的 ModelAndView 此时会判断是否存在异常如果存在异常则执行 HandlerExceptionResolver 进行异常处理选择一个适合的 ViewResolver 进行视图解析根据 Model和View 来渲染视图渲染视图完毕执行拦截器的 afterCompletion(…) 方法【逆向】将渲染结果返回给客户端
