SpringMVC(后)SSM整合

10、文件上传和下载

10.1、文件下载

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

使用ResponseEntity实现下载文件的功能

@RequestMapping("/testDown")
public ResponseEntity<byte[]> testResponseEntity(HttpSession session) throwsIOException {//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.jpg");//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MultiValueMap<String, String> headers = new HttpHeaders();//设置要下载方式以及下载文件的名字headers.add("Content-Disposition", "attachment;filename=1.jpg");//设置响应状态码HttpStatus statusCode = HttpStatus.OK;//创建ResponseEntity对象ResponseEntity<byte[]> responseEntity = new ResponseEntity<>(bytes, headers,statusCode);//关闭输入流is.close();return responseEntity;
}

10.2、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enctype=“multipart/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：

①添加依赖：

<!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload -->
<dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.3.1</version>
</dependency>

②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 id="multipartResolver"
class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
</bean>

③控制器方法：

@RequestMapping("/testUp")
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";
}

11、拦截器

11.1、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：

<bean class="com.atguigu.interceptor.FirstInterceptor"></bean>
<ref bean="firstInterceptor"></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:interceptor><mvc:mapping path="/**"/><mvc:exclude-mapping path="/testRequestEntity"/><ref bean="firstInterceptor"></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
-->

11.2、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()

afterCompletion：处理完视图和模型数据，渲染视图完毕之后执行afterCompletion()

11.3、多个拦截器的执行顺序

①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afterCompletion()会按照配置的反序执行

②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afterCompletion()会执行

12、异常处理器

12.1、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：

<beanclass="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver"><property name="exceptionMappings"><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 key="java.lang.ArithmeticException">error</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--><property name="exceptionAttribute" value="ex"></property>
</bean>

12.2、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";}
}

13、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

13.1、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。

public class WebInit extendsAbstractAnnotationConfigDispatcherServletInitializer {/*** 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[]{"/"};}/*** 添加过滤器* @return*/@Overrideprotected Filter[] getServletFilters() {CharacterEncodingFilter encodingFilter = new CharacterEncodingFilter();encodingFilter.setEncoding("UTF-8");encodingFilter.setForceRequestEncoding(true);HiddenHttpMethodFilter hiddenHttpMethodFilter = newHiddenHttpMethodFilter();return new Filter[]{encodingFilter, hiddenHttpMethodFilter};}
}

13.2、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
}

13.3、创建WebConfig配置类，代替SpringMVC的配置文件

@Configuration
//扫描组件
@ComponentScan("com.atguigu.mvc.controller")
//开启MVC注解驱动
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {//使用默认的servlet处理静态资源@Overridepublic void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {configurer.enable();}//配置文件上传解析器@Beanpublic CommonsMultipartResolver multipartResolver(){return new CommonsMultipartResolver();}//配置拦截器@Overridepublic void addInterceptors(InterceptorRegistry registry) {FirstInterceptor firstInterceptor = new FirstInterceptor();registry.addInterceptor(firstInterceptor).addPathPatterns("/**");}//配置视图控制/*@Overridepublic void addViewControllers(ViewControllerRegistry registry) {registry.addViewController("/").setViewName("index");}*///配置异常映射/*@Overridepublic void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> 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 = newServletContextTemplateResolver(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;}
}

13.4、测试功能

@RequestMapping("/")
public String index(){return "index";
}

14、SpringMVC执行流程

14.1、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

14.2、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。

①初始化WebApplicationContext

所在类：org.springframework.web.servlet.FrameworkServlet

protected WebApplicationContext initWebApplicationContext() {WebApplicationContext rootContext = WebApplicationContextUtils.getWebApplicationContext(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);}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 = findWebApplicationContext();}if (wac == null) {// No context instance is defined for this servlet -> create a local one// 创建WebApplicationContextwac = 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WebApplicationContextonRefresh(wac);}}if (this.publishContext) {// Publish the context as a servlet context attribute.// 将IOC容器在应用域共享String attrName = getServletContextAttributeName();getServletContext().setAttribute(attrName, wac);}return wac;
}

②创建WebApplicationContext

所在类：org.springframework.web.servlet.FrameworkServlet

protected WebApplicationContext createWebApplicationContext(@Nullable ApplicationContext parent) {Class<?> contextClass = getContextClass();if (!ConfigurableWebApplicationContext.class.isAssignableFrom(contextClass)){throw new ApplicationContextException("Fatal initialization error in servlet with name '" +getServletName() +"': custom WebApplicationContext class [" + contextClass.getName() +"] is not of type ConfigurableWebApplicationContext");}// 通过反射创建 IOC 容器对象ConfigurableWebApplicationContext wac = (ConfigurableWebApplicationContext)BeanUtils.instantiateClass(contextClass);wac.setEnvironment(getEnvironment());// 设置父容器wac.setParent(parent);String configLocation = getContextConfigLocation();if (configLocation != null) {wac.setConfigLocation(configLocation);}configureAndRefreshWebApplicationContext(wac);return wac;
}

③DispatcherServlet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);
}

14.3、DispatcherServlet调用组件处理请求

①processRequest()

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 = buildLocaleContext(request);RequestAttributes previousAttributes = RequestContextHolder.getRequestAttributes();ServletRequestAttributes requestAttributes = buildRequestAttributes(request,response, previousAttributes);WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);asyncManager.registerCallableInterceptor(FrameworkServlet.class.getName(),new RequestBindingInterceptor());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doService(request, response);}catch (ServletException | IOException ex) {failureCause = ex;throw ex;}catch (Throwable ex) {failureCause = ex;throw new NestedServletException("Request processing failed", ex);}finally {resetContextHolders(request, previousLocaleContext, previousAttributes);if (requestAttributes != null) {requestAttributes.requestCompleted();}logResult(request, response, failureCause, asyncManager);publishRequestHandledEvent(request, response, startTime, failureCause);}
}

②doService()

所在类：org.springframework.web.servlet.DispatcherServlet

@Override
protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception {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.Map<String, Object> attributesSnapshot = null;if (WebUtils.isIncludeRequest(request)) {attributesSnapshot = new HashMap<>();Enumeration<?> attrNames = request.getAttributeNames();while (attrNames.hasMoreElements()) {String attrName = (String) attrNames.nextElement();if (this.cleanupAfterInclude || attrName.startsWith(DEFAULT_STRATEGIES_PREFIX)) {attributesSnapshot.put(attrName,request.getAttribute(attrName));}}}// Make framework objects available to handlers and view objects.request.setAttribute(WEB_APPLICATION_CONTEXT_ATTRIBUTE,getWebApplicationContext());request.setAttribute(LOCALE_RESOLVER_ATTRIBUTE, this.localeResolver);request.setAttribute(THEME_RESOLVER_ATTRIBUTE, this.themeResolver);request.setAttribute(THEME_SOURCE_ATTRIBUTE, 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doDispatch(request, response);}finally {if(!WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) {// Restore the original attribute snapshot, in case of an include.if (attributesSnapshot != null) {restoreAttributesAfterInclude(request, attributesSnapshot);}}if (requestPath != null) {ServletRequestPathUtils.clearParsedRequestPath(request);}}
}

③doDispatch()

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 {ModelAndView mv = null;Exception dispatchException = null;try {processedRequest = checkMultipart(request);multipartRequestParsed = (processedRequest != request);// Determine handler for the current request./*mappedHandler：调用链包含handler、interceptorList、interceptorIndexhandler：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 = getHandler(processedRequest);if (mappedHandler == null) {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 = 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;}applyDefaultViewName(processedRequest, mv);// 调用拦截器的postHandle()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 otherscenarios.dispatchException = new NestedServletException("Handler dispatchfailed", err);}// 后续处理：处理模型数据和渲染视图 processDispatchResult(processedRequest, response, mappedHandler, mv,dispatchException);}catch (Exception ex) {triggerAfterCompletion(processedRequest, response, mappedHandler, ex);}catch (Throwable err) {triggerAfterCompletion(processedRequest, response, mappedHandler,new NestedServletException("Handler processingfailed",err));}finally {if (asyncManager.isConcurrentHandlingStarted()) {// Instead of postHandle and afterCompletionif (mappedHandler != null) {mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response);}}else {// Clean up any resources used by a multipart request.if (multipartRequestParsed) {cleanupMultipart(processedRequest);}}}
}                                                          

④processDispatchResult()

private void processDispatchResult(HttpServletRequest request,HttpServletResponse response,@Nullable HandlerExecutionChainmappedHandler, @Nullable ModelAndView mv,@Nullable Exception exception) throws Exception {boolean errorView = false;if (exception != null) {if (exception instanceof ModelAndViewDefiningException) {logger.debug("ModelAndViewDefiningException encountered",exception);mv = ((ModelAndViewDefiningException) exception).getModelAndView();}else {Object handler = (mappedHandler != null ? mappedHandler.getHandler(): null);mv = 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render(mv, request, response);if (errorView) {WebUtils.clearErrorRequestAttributes(request);}}else {if (logger.isTraceEnabled()) {logger.trace("No view rendering, null ModelAndView returned.");}}if (WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted()) {// Concurrent handling started during a forwardreturn;}if (mappedHandler != null) {// Exception (if any) is already handled..// 调用拦截器的afterCompletion()mappedHandler.triggerAfterCompletion(request, response, null);}
}                                   

14.4、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。

四、SSM整合

4.1、ContextLoaderListener

Spring提供了监听器ContextLoaderListener，实现ServletContextListener接口，可监听

ServletContext的状态，在web服务器的启动，读取Spring的配置文件，创建Spring的IOC容器。web应用中必须在web.xml中配置

<listener><!--配置Spring的监听器，在服务器启动时加载Spring的配置文件Spring配置文件默认位置和名称：/WEB-INF/applicationContext.xml可通过上下文参数自定义Spring配置文件的位置和名称--><listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<!--自定义Spring配置文件的位置和名称-->
<context-param><param-name>contextConfigLocation</param-name><param-value>classpath:spring.xml</param-value>
</context-param>

4.2、准备工作

①创建Maven Module

②导入依赖

<packaging>war</packaging>
<properties><spring.version>5.3.1</spring.version>
</properties>
<dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-beans</artifactId><version>${spring.version}</version></dependency><!--springmvc--><dependency><groupId>org.springframework</groupId><artifactId>spring-web</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-webmvc</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-jdbc</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-aspects</artifactId><version>${spring.version}</version></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-test</artifactId><version>${spring.version}</version></dependency><!-- Mybatis核心 --><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.7</version></dependency><!--mybatis和spring的整合包--><dependency><groupId>org.mybatis</groupId><artifactId>mybatis-spring</artifactId><version>2.0.6</version></dependency><!-- 连接池 --><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.0.9</version></dependency><!-- junit测试 --><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version><scope>test</scope></dependency><!-- MySQL驱动 --><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.16</version></dependency><!-- log4j日志 --><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>1.2.17</version></dependency><!-- https://mvnrepository.com/artifact/com.github.pagehelper/pagehelper -->   <dependency><groupId>com.github.pagehelper</groupId><artifactId>pagehelper</artifactId><version>5.2.0</version></dependency><!-- 日志 --><dependency><groupId>ch.qos.logback</groupId><artifactId>logback-classic</artifactId><version>1.2.3</version></dependency><!-- ServletAPI --><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.1.0</version><scope>provided</scope></dependency><dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-databind</artifactId><version>2.12.1</version></dependency><dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.3.1</version></dependency><!-- Spring5和Thymeleaf整合包 --><dependency><groupId>org.thymeleaf</groupId><artifactId>thymeleaf-spring5</artifactId><version>3.0.12.RELEASE</version></dependency>
</dependencies> 

③创建表

CREATE TABLE `t_emp` (`emp_id` int(11) NOT NULL AUTO_INCREMENT,`emp_name` varchar(20) DEFAULT NULL,`age` int(11) DEFAULT NULL,`sex` char(1) DEFAULT NULL,`email` varchar(50) DEFAULT NULL,PRIMARY KEY (`emp_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8

4.3、配置web.xml

<!-- 配置Spring的编码过滤器 -->
<filter><filter-name>CharacterEncodingFilter</filter-name><filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class><init-param><param-name>encoding</param-name><param-value>UTF-8</param-value></init-param><init-param><param-name>forceEncoding</param-name><param-value>true</param-value></init-param>
</filter>
<filter-mapping><filter-name>CharacterEncodingFilter</filter-name><url-pattern>/*</url-pattern>
</filter-mapping>
<!-- 配置处理请求方式PUT和DELETE的过滤器 -->
<filter><filter-name>HiddenHttpMethodFilter</filter-name><filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filterclass>
</filter>
<filter-mapping><filter-name>HiddenHttpMethodFilter</filter-name><url-pattern>/*</url-pattern>
</filter-mapping>
<!-- 配置SpringMVC的前端控制器 -->
<servlet><servlet-name>DispatcherServlet</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servletclass><!-- 设置SpringMVC的配置文件的位置和名称 --><init-param><param-name>contextConfigLocation</param-name><param-value>classpath:SpringMVC.xml</param-value></init-param><load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping><servlet-name>DispatcherServlet</servlet-name><url-pattern>/</url-pattern>
</servlet-mapping>
<!-- 设置Spring的配置文件的位置和名称 -->
<context-param><param-name>contextConfigLocation</param-name><param-value>classpath:Spring.xml</param-value>
</context-param>
<!-- 配置Spring的监听器 -->
<listener><listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

4.4、创建SpringMVC的配置文件并配置

<!--扫描组件-->
<context:component-scan base-package="com.atguigu.ssm.controller">
</context:component-scan>
<!--配置视图解析器-->
<bean id="viewResolver"class="org.thymeleaf.spring5.view.ThymeleafViewResolver"><property name="order" value="1"/><property name="characterEncoding" value="UTF-8"/><property name="templateEngine"><bean class="org.thymeleaf.spring5.SpringTemplateEngine"><property name="templateResolver"><beanclass="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver"><!-- 视图前缀 --><property name="prefix" value="/WEB-INF/templates/"/><!-- 视图后缀 --><property name="suffix" value=".html"/><property name="templateMode" value="HTML5"/><property name="characterEncoding" value="UTF-8" /></bean></property></bean></property>
</bean>
<!-- 配置访问首页的视图控制 -->
<mvc:view-controller path="/" view-name="index"></mvc:view-controller>
<!-- 配置默认的servlet处理静态资源 -->
<mvc:default-servlet-handler />
<!-- 开启MVC的注解驱动 -->
<mvc:annotation-driven />

4.5、搭建MyBatis环境

①创建属性文件jdbc.properties

jdbc.user=root
jdbc.password=atguigu
jdbc.url=jdbc:mysql://localhost:3306/ssm?serverTimezone=UTC
jdbc.driver=com.mysql.cj.jdbc.Driver

②创建MyBatis的核心配置文件mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration><settings><!--将下划线映射为驼峰--><setting name="mapUnderscoreToCamelCase" value="true"/></settings><plugins><!--配置分页插件--><plugin interceptor="com.github.pagehelper.PageInterceptor"></plugin></plugins>
</configuration>

③创建Mapper接口和映射文件

public interface EmployeeMapper {
List<Employee> getEmployeeList();
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.atguigu.ssm.mapper.EmployeeMapper"><select id="getEmployeeList" resultType="Employee">select * from t_emp</select>
</mapper>

④创建日志文件log4j.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/"><appender name="STDOUT" class="org.apache.log4j.ConsoleAppender"><param name="Encoding" value="UTF-8" /><layout class="org.apache.log4j.PatternLayout"><param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) \n" /></layout></appender><logger name="java.sql"><level value="debug" /></logger><logger name="org.apache.ibatis"><level value="info" /></logger><root><level value="debug" /><appender-ref ref="STDOUT" /></root>
</log4j:configuration>

4.6、创建Spring的配置文件并配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttps://www.springframework.org/schema/context/spring-context.xsd"><!--扫描组件--><context:component-scan base-package="com.atguigu.ssm"><context:exclude-filter type="annotation"expression="org.springframework.stereotype.Controller"/></context:component-scan><!-- 引入jdbc.properties --><context:property-placeholder location="classpath:jdbc.properties"></context:property-placeholder><!-- 配置Druid数据源 --><bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource"><property name="driverClassName" value="${jdbc.driver}"></property><property name="url" value="${jdbc.url}"></property><property name="username" value="${jdbc.username}"></property><property name="password" value="${jdbc.password}"></property></bean><!-- 配置用于创建SqlSessionFactory的工厂bean --><bean class="org.mybatis.spring.SqlSessionFactoryBean"><!-- 设置MyBatis配置文件的路径（可以不设置） --><property name="configLocation" value="classpath:mybatis-config.xml"></property><!-- 设置数据源 --><property name="dataSource" ref="dataSource"></property><!-- 设置类型别名所对应的包 --><property name="typeAliasesPackage" value="com.atguigu.ssm.pojo"></property><!--设置映射文件的路径若映射文件所在路径和mapper接口所在路径一致，则不需要设置--><!--<property name="mapperLocations" value="classpath:mapper/*.xml"></property>--></bean><!--配置mapper接口的扫描配置由mybatis-spring提供，可以将指定包下所有的mapper接口创建动态代理并将这些动态代理作为IOC容器的bean管理--><bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"><property name="basePackage" value="com.atguigu.ssm.mapper"></property></bean>
</beans>

4.7、测试功能

①创建组件

实体类Employee

public class Employee {private Integer empId;private String empName;private Integer age;private String sex;private String email;public Employee() {}public Employee(Integer empId, String empName, Integer age, String sex,String email) {this.empId = empId;this.empName = empName;this.age = age;this.sex = sex;this.email = email;}public Integer getEmpId() {return empId;}public void setEmpId(Integer empId) {this.empId = empId;}public String getEmpName() {return empName;}public void setEmpName(String empName) {this.empName = empName;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public String getEmail() {return email;}public void setEmail(String email) {this.email = email;}
}

创建控制层组件EmployeeController

@Controller
public class EmployeeController {@Autowiredprivate EmployeeService employeeService;@RequestMapping(value = "/employee/page/{pageNum}", method = RequestMethod.GET)public String getEmployeeList(Model model, @PathVariable("pageNum") Integer pageNum){PageInfo<Employee> page = employeeService.getEmployeeList(pageNum);model.addAttribute("page", page);return "employee_list";}
}

创建接口EmployeeService

public interface EmployeeService {PageInfo<Employee> getEmployeeList(Integer pageNum);
}

创建实现类EmployeeServiceImpl

@Service
public class EmployeeServiceImpl implements EmployeeService {@Autowiredprivate EmployeeMapper employeeMapper;@Overridepublic PageInfo<Employee> getEmployeeList(Integer pageNum) {PageHelper.startPage(pageNum, 4);List<Employee> list = employeeMapper.getEmployeeList();PageInfo<Employee> page = new PageInfo<>(list, 5);return page;}
}

②创建页面

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org"><head><meta charset="UTF-8"><title>Employee Info</title><link rel="stylesheet" th:href="@{/static/css/index_work.css}"></head><body><table><tr><th colspan="6">Employee Info</th></tr><tr><th>emp_id</th><th>emp_name</th><th>age</th><th>sex</th><th>email</th><th>options</th></tr><tr th:each="employee : ${page.list}"><td th:text="${employee.empId}"></td><td th:text="${employee.empName}"></td><td th:text="${employee.age}"></td><td th:text="${employee.sex}"></td><td th:text="${employee.email}"></td><td><a href="">delete</a><a href="">update</a></td></tr><tr><td colspan="6"><span th:if="${page.hasPreviousPage}"><a th:href="@{/employee/page/1}">首页</a><a th:href="@{'/employee/page/'+${page.prePage}}">上一页</a></span><span th:each="num : ${page.navigatepageNums}"><a th:if="${page.pageNum==num}"th:href="@{'/employee/page/'+${num}}" th:text="'['+${num}+']'" style="color:red;"></a><a th:if="${page.pageNum!=num}"th:href="@{'/employee/page/'+${num}}" th:text="${num} "></a></span><span th:if="${page.hasNextPage}"><a th:href="@{'/employee/page/'+${page.nextPage}}">下一页</a><a th:href="@{'/employee/page/'+${page.pages}}">末页</a></span></td></tr></table></body>
</html>

③访问测试分页功能

创建接口EmployeeService```java
public interface EmployeeService {PageInfo<Employee> getEmployeeList(Integer pageNum);
}

创建实现类EmployeeServiceImpl

@Service
public class EmployeeServiceImpl implements EmployeeService {@Autowiredprivate EmployeeMapper employeeMapper;@Overridepublic PageInfo<Employee> getEmployeeList(Integer pageNum) {PageHelper.startPage(pageNum, 4);List<Employee> list = employeeMapper.getEmployeeList();PageInfo<Employee> page = new PageInfo<>(list, 5);return page;}
}

②创建页面

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org"><head><meta charset="UTF-8"><title>Employee Info</title><link rel="stylesheet" th:href="@{/static/css/index_work.css}"></head><body><table><tr><th colspan="6">Employee Info</th></tr><tr><th>emp_id</th><th>emp_name</th><th>age</th><th>sex</th><th>email</th><th>options</th></tr><tr th:each="employee : ${page.list}"><td th:text="${employee.empId}"></td><td th:text="${employee.empName}"></td><td th:text="${employee.age}"></td><td th:text="${employee.sex}"></td><td th:text="${employee.email}"></td><td><a href="">delete</a><a href="">update</a></td></tr><tr><td colspan="6"><span th:if="${page.hasPreviousPage}"><a th:href="@{/employee/page/1}">首页</a><a th:href="@{'/employee/page/'+${page.prePage}}">上一页</a></span><span th:each="num : ${page.navigatepageNums}"><a th:if="${page.pageNum==num}"th:href="@{'/employee/page/'+${num}}" th:text="'['+${num}+']'" style="color:red;"></a><a th:if="${page.pageNum!=num}"th:href="@{'/employee/page/'+${num}}" th:text="${num} "></a></span><span th:if="${page.hasNextPage}"><a th:href="@{'/employee/page/'+${page.nextPage}}">下一页</a><a th:href="@{'/employee/page/'+${page.pages}}">末页</a></span></td></tr></table></body>
</html>

③访问测试分页功能

localhost:8080/employee/page/1