商务网站模板下载,公司做网站让拍照备案,网站界面设计需要,用美图秀秀做网站图片九、HttpMessageConverter HttpMessageConverter #xff0c;报文信息转换器#xff0c;将请求报文转换为 Java 对象#xff0c;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#xff1a; RequestBody #xff0c; ResponseBody #xff…九、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 !DOCTYPE html
html langen xmlns:thhttp://www.thymeleaf.org
headmeta charsetUTF-8title首页/title
/head
body
h1首页/h1
form th:action{/testRequestBody} methodpostinput typetext nameusernamebrinput typetext namepasswordbrinput typesubmit value测试RequestBodybr
/form
/body
/html Controller
public class HttpController {RequestMapping(testRequestBody)public String testRequestBody(RequestBody String requestBody){System.out.println(requestBody:requestBody);return success;}
} !DOCTYPE html
html langen xmlns:thhttp://www.thymeleaf.org
headmeta charsetUTF-8titleTitle/title
/head
body
成功了呀
/body
/html 输出结果 requestBody:usernamehelloWorldpassword123456 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 form th:action{/testRequestEntity} methodpostinput typetext nameusernamebrinput typetext namepasswordbrinput typesubmit value测试RequestEntitybr
/form RequestMapping(/testRequestEntity)public String testRequestEntity(RequestEntityString requestEntity){//当前requestEntity表示整个请求报文的信息System.out.println(请求头requestEntity.getHeaders());System.out.println(请求体requestEntity.getBody());return success;} 输出结果 请求头[host:localhost:8080, user-agent:Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/116.0, accept:text/html,application/xhtmlxml,application/xml;q0.9,image/avif,image/webp,*/*;q0.8, accept-language:zh-CN,zh;q0.8,zh-TW;q0.7,zh-HK;q0.5,en-US;q0.3,en;q0.2, accept-encoding:gzip, deflate, br, content-length:29, origin:http://localhost:8080, connection:keep-alive, referer:http://localhost:8080/springMVC/, cookie:JSESSIONID05A1276222C18EB3F9DB64EDC1381B98; Idea-4579b2afcf1f07a0-0b0d-40ab-934f-8398b410993b, upgrade-insecure-requests:1, sec-fetch-dest:document, sec-fetch-mode:navigate, sec-fetch-site:same-origin, sec-fetch-user:?1, Content-Type:application/x-www-form-urlencoded;charsetUTF-8] 请求体usernameadminpassword12314 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 a th:href{/testResponse}通过servletAPI的response对象响应浏览器数据/abr
a th:href{/testResponseBody}通过ResponseBody响应浏览器数据/abr RequestMapping(/testResponse)public void testResponse(HttpServletResponse response) throws IOException {//将print中的内容直接作为响应报文的响应体响应到浏览器中response.getWriter().print(hello,response);}RequestMapping(/testResponseBody)ResponseBodypublic String testResponseBody(){//加上ResponseBody注解就是success直接作为返回值,而不加ResponseBody注解就是跳转到success视图return success;} !DOCTYPE html
html langen xmlns:thhttp://www.thymeleaf.org
headmeta charsetUTF-8titleTitle/title
/head
body
h1成功了呀/h1
/body
/html 结果浏览器页面显示 success 4、SpringMVC处理json ResponseBody 处理 json 的步骤 a 导入 jackson 的依赖 dependencygroupIdcom.fasterxml.jackson.core/groupIdartifactIdjackson-databind/artifactIdversion2.13.4.2/version/dependency b 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 mvc:annotation-driven / c 在处理器方法上使用 ResponseBody 注解进行标识 d 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)ResponseBodypublic User testResponseUser(){return new User(1001,admin,123456,22,男);} 浏览器的页面中展示的结果 {id:1001,username:admin,password:123456,age:22,sex: 男 } 5、SpringMVC处理ajax a 请求超链接 a th:href{/testResponseUser}通过ResponseBody响应浏览器User对象/abr 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 十、文件上传和下载 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.webp/a
/body
/html mvc:view-controller path/file view-namefile/mvc:view-controller Controller
public class FileAndDownController {RequestMapping(/testDown)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.webp);//创建输入流InputStream is new FileInputStream(realPath);//创建字节数组byte[] bytes new byte[is.available()];//is.available()获取输入流文件所有的字节//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();//设置要下载方式以及下载文件的名字固定的只需要修改下载的名字headers.add(Content-Disposition, attachment;filename1.webp);//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;}
} 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-data SpringMVC 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 a 添加依赖 !-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload --dependencygroupIdcommons-fileupload/groupIdartifactIdcommons-fileupload/artifactIdversion1.3.1/version/dependency b 在 SpringMVC 的配置文件中添加配置 !--配饰文件上传解析器将上传的文件封装为MultipartFile--bean idmultipartResolver classorg.springframework.web.multipart.commons.CommonsMultipartResolver/bean c 控制器方法 RequestMapping(/testUp)public String testUp(MultipartFile photo,HttpSession session) throws IOException {String filename photo.getOriginalFilename();ServletContext servletContext session.getServletContext();String photoPath servletContext.getRealPath(photo);File file new File(photoPath);//判断photoPath对应的路径是否存在if(!file.exists()){//若不存在则创建目录file.mkdirs();}String finalPathphotoPathFile.separatorfilename;photo.transferTo(new File(finalPath));return success;} 但是有一个问题上传同名文件会被替代。
解决 RequestMapping(/testUp)public String testUp(MultipartFile photo,HttpSession session) throws IOException {//获取上传文件的文件名String filename photo.getOriginalFilename();//获取上传的文件的后缀名String suffixNamefilename.substring(filename.lastIndexOf(.));//将UUID作为文件名String uuid UUID.randomUUID().toString();//将uuid和后缀名拼接后的结果作为最终的文件名filenameuuidsuffixName;//通过ServletContext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);//判断photoPath对应的路径是否存在if(!file.exists()){//若不存在则创建目录file.mkdirs();}String finalPathphotoPathFile.separatorfilename;photo.transferTo(new File(finalPath));return success;}
此时上传相同的文件就不会替换了 十一、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 !--配置拦截器--mvc:interceptors!-- 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 --
!-- bean classcom.atguigu.mvc.interceptors.FirstInterceptor/bean--
!-- ref beanfirstInterceptor/ref--mvc:interceptormvc:mapping path/**/mvc:exclude-mapping path//ref beanfirstInterceptor/ref/mvc:interceptor/mvc:interceptors
!--
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
-- TestController: Controller
public class TestController {RequestMapping(/**/testInterceptor)public String testInterceptor(){return success;}
} !DOCTYPE html
html langen xmlns:thhttp://www.thymeleaf.org
headmeta charsetUTF-8titleTitle/title
/head
body
h1首页来了/h1
a th:href{/testInterceptor}测试拦截器/a
/body
/html FirstInterceptor: Component
public class FirstInterceptor implements HandlerInterceptor {Override//控制器执行方法前执行public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println(FirstInterceptor----preHandle);//返回false进行拦截返回true放行return true;}Override//控制器执行方法后执行public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println(FirstInterceptor----postHandle);}Override//视图渲染后执行public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println(FirstInterceptor----afterCompletion);}
}2、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 a 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 b 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 当secondInterceptor的 preHandle() 返回了 false 输出结果 FirstInterceptor----preHandle secondInterceptor----preHandle FirstInterceptor----afterComplation FirstInterceptor: Component
public class FirstInterceptor implements HandlerInterceptor {Override//控制器执行方法前执行public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println(FirstInterceptor----preHandle);//返回false进行拦截返回true放行return true;}Override//控制器执行方法后执行public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println(FirstInterceptor----postHandle);}Override//视图渲染后执行public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println(FirstInterceptor----afterCompletion);}
} SecondInterceptor: Component
public class SecondInterceptor implements HandlerInterceptor {Override//控制器执行方法前执行public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {System.out.println(secondInterceptor----preHandle);//返回false进行拦截返回true放行return true;}Override//控制器执行方法后执行public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println(secondInterceptor----postHandle);}Override//视图渲染后执行public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println(secondInterceptor----afterCompletion);}
} 输出结果 看源码 十二、异常处理器 1、基于配置的异常处理 SpringMVC 提供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 !--配置异常处理--bean classorg.springframework.web.servlet.handler.SimpleMappingExceptionResolverproperty nameexceptionMappings!--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--propsprop keyjava.lang.ArithmeticExceptionerror/prop/props/property!--设置将异常信息共享在请求域中的键--property nameexceptionAttribute valueex/property/bean RequestMapping(/testException)public String testExceptionHandler(){System.out.println(1/0);return success;} a th:href{/testException}测试异常处理/abr !DOCTYPE html
html langen xmlns:thhttp://www.thymeleaf.org
headmeta charsetUTF-8titleTitle/title
/head
body
h1出现错误/h1br
p th:text${ex}/pbr
/body
/html 2、基于注解的异常处理
ExceptionController:
//是Component的一个扩展组件
ControllerAdvice
public class ExceptionController {ExceptionHandler(value {ArithmeticException.class,NullPointerException.class})public String testException(Exception ex, Model model){//使用Model共享数据也就是获取异常信息model.addAttribute(ex,ex);return error;}
}
!DOCTYPE html
html langen xmlns:thhttp://www.thymeleaf.org
headmeta charsetUTF-8titleTitle/title
/head
body
h1出现错误/h1br
p th:text${ex}/pbr
/body
/html RequestMapping(/testException)public String testExceptionHandler(){System.out.println(1/0);return success;} 十三、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Overrideprotected Class?[] getRootConfigClasses() {return new Class[]{SpringConfig.class};}//指定springMVC的配置类Overrideprotected Class?[] getServletConfigClasses() {return new Class[]{WebConfig.class};}//指定DispatcherServlet的映射规则即url-patternOverrideprotected String[] getServletMappings() {return new String[]{/};}//注册过滤器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)
//5.mvc注解驱动
EnableWebMvc
public class WebConfig implements WebMvcConfigurer {//4.default-servlet-handler//使用默认的servlet处理静态资源Overridepublic void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {configurer.enable();}//6.文件上传解析器//配置文件上传解析器Beanpublic CommonsMultipartResolver multipartResolver() {return new CommonsMultipartResolver();}//8拦截器//配置拦截器Overridepublic void addInterceptors(InterceptorRegistry registry) {TestInterceptor testInterceptor new TestInterceptor();registry.addInterceptor(testInterceptor).addPathPatterns(/**);}//3.view-controller//配置视图控制Overridepublic void addViewControllers(ViewControllerRegistry registry) {registry.addViewController(/hello).setViewName(index);}//7.异常处理//配置异常映射Overridepublic void configureHandlerExceptionResolvers(ListHandlerExceptionResolver resolvers) {SimpleMappingExceptionResolver exceptionResolver new SimpleMappingExceptionResolver();Properties prop new Properties();prop.setProperty(java.lang.ArithmeticException, error);//设置异常映射exceptionResolver.setExceptionMappings(prop);//设置共享异常信息的键exceptionResolver.setExceptionAttribute(ex);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 Controller
public class TestController {RequestMapping(/)public String index(){return index;}
}十三、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。 a 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) {wac this.webApplicationContext;if (wac instanceof ConfigurableWebApplicationContext) {ConfigurableWebApplicationContext cwac (ConfigurableWebApplicationContext)wac;if (!cwac.isActive()) {if (cwac.getParent() null) {cwac.setParent(rootContext);}this.configureAndRefreshWebApplicationContext(cwac);}}}if (wac null) {wac this.findWebApplicationContext();}if (wac null) {wac this.createWebApplicationContext(rootContext);}if (!this.refreshEventReceived) {synchronized(this.onRefreshMonitor) {this.onRefresh(wac);}}if (this.publishContext) {String attrName this.getServletContextAttributeName();this.getServletContext().setAttribute(attrName, wac);}return wac;} b 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 {ConfigurableWebApplicationContext wac (ConfigurableWebApplicationContext)BeanUtils.instantiateClass(contextClass);wac.setEnvironment(this.getEnvironment());wac.setParent(parent);String configLocation this.getContextConfigLocation();if (configLocation ! null) {wac.setConfigLocation(configLocation);}this.configureAndRefreshWebApplicationContext(wac);return wac;}} cDispatcherServlet 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) {this.initMultipartResolver(context);this.initLocaleResolver(context);this.initThemeResolver(context);this.initHandlerMappings(context);this.initHandlerAdapters(context);this.initHandlerExceptionResolvers(context);this.initRequestToViewNameTranslator(context);this.initViewResolvers(context);this.initFlashMapManager(context);} 3、DispatcherServlet调用组件处理请求 aprocessRequest() 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 {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);}} bdoService() 所在类 org.springframework.web.servlet.DispatcherServlet protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception {this.logRequest(request);MapString, Object attributesSnapshot null;if (WebUtils.isIncludeRequest(request)) {attributesSnapshot new HashMap();Enumeration attrNames request.getAttributeNames();label116:while(true) {String attrName;do {if (!attrNames.hasMoreElements()) {break label116;}attrName (String)attrNames.nextElement();} while(!this.cleanupAfterInclude !attrName.startsWith(org.springframework.web.servlet));attributesSnapshot.put(attrName, request.getAttribute(attrName));}}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 previousRequestPath null;if (this.parseRequestPath) {previousRequestPath (RequestPath)request.getAttribute(ServletRequestPathUtils.PATH_ATTRIBUTE);ServletRequestPathUtils.parseAndCache(request);}try {this.doDispatch(request, response);} finally {if (!WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted() attributesSnapshot ! null) {this.restoreAttributesAfterInclude(request, attributesSnapshot);}if (this.parseRequestPath) {ServletRequestPathUtils.setParsedRequestPath(previousRequestPath, request);}}} cdoDispatch() 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;mappedHandler this.getHandler(processedRequest);if (mappedHandler null) {this.noHandlerFound(processedRequest, response);return;}HandlerAdapter ha this.getHandlerAdapter(mappedHandler.getHandler());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;}mv ha.handle(processedRequest, response, mappedHandler.getHandler());if (asyncManager.isConcurrentHandlingStarted()) {return;}this.applyDefaultViewName(processedRequest, mv);mappedHandler.applyPostHandle(processedRequest, response, mv);} catch (Exception var20) {dispatchException var20;} catch (Throwable var21) {dispatchException new NestedServletException(Handler dispatch failed, var21);}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()) {if (mappedHandler ! null) {mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);}} else if (multipartRequestParsed) {this.cleanupMultipart(processedRequest);}}} dprocessDispatchResult() 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;}}if (mv ! null !mv.wasCleared()) {this.render(mv, request, response);if (errorView) {WebUtils.clearErrorRequestAttributes(request);}} else if (this.logger.isTraceEnabled()) {this.logger.trace(No view rendering, null ModelAndView returned.);}if (!WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) {if (mappedHandler ! null) {mappedHandler.triggerAfterCompletion(request, response, (Exception)null);}}} 4、SpringMVC的执行流程 1) 用户向服务器发送请求请求被 SpringMVC 前端控制器 DispatcherServlet 捕获。 2) 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 a) 不存在 i. 再判断是否配置了 mvc:default-servlet-handler ii. 如果没配置则控制台报映射查找不到客户端展示 404 错误 iii. 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 b) 存在则执行下面的流程 3) 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。 4) DispatcherServlet 根据获得的 Handler 选择一个合适的 HandlerAdapter 。 5) 如果成功获得 HandlerAdapter 此时将开始执行拦截器的 preHandler(…) 方法【正向】 6) 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 a) 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 b) 数据转换对请求消息进行数据转换。如 String 转换成 Integer 、 Double 等 c) 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 d) 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 7) Handler 执行完成后向 DispatcherServlet 返回一个 ModelAndView 对象。 8) 此时将开始执行拦截器的 postHandle(...) 方法【逆向】。 9) 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。 10) 渲染视图完毕执行拦截器的 afterCompletion(…) 方法【逆向】。 11) 将渲染结果返回给客户端。
