• SpringMVC学习笔记（三）

    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

    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 extends AbstractAnnotationConfigDispatcherServletInitializer {
    @Override
    //设置一个配置类代替Spring的配置文件
    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{SpringConfig.class};
    }

    @Override
    //设置一个配置类代替SpringMVC的配置文件
    protected Class<?>[] getServletConfigClasses() {
        return new Class[]{WebConfig.class};
    }

    @Override
    //设置SpringMVC的前端控制器DispatcherServlet的url-pattern
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }

    @Override
    //设置当前的过滤器
    protected Filter[] getServletFilters() {
        //创建编码过滤器
        CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();
        characterEncodingFilter.setEncoding("UTF-8");
        characterEncodingFilter.setForceEncoding(true);
        //创建处理请求方式的过滤器
        HiddenHttpMethodFilter hiddenHttpMethodFilter = new HiddenHttpMethodFilter();
        return new Filter[]{characterEncodingFilter, hiddenHttpMethodFilter};
    }
}

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    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 }

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    13.3 创建WebConfig配置类，代替SpringMVC的配置文件

    //将类标识为配置类
@Configuration
//扫描组件
@ComponentScan("com.atguigu.controller")
//开启mvc的注解驱动
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {

    @Override
    //默认的servlet处理静态资源
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    @Override
    //配置视图解析器
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("index");
    }

    //@Bean注解可以将标识的方法的返回值作为bean进行管理，bean的id为方法的方法名
    @Bean
    public CommonsMultipartResolver multipartResolver(){
        return new CommonsMultipartResolver();
    }

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        FirstInterceptor firstInterceptor = new FirstInterceptor();
        registry.addInterceptor(firstInterceptor).addPathPatterns("/**");
    }

    @Override
    //配置异常解析器
    public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
        SimpleMappingExceptionResolver exceptionResolver = new SimpleMappingExceptionResolver();
        Properties prop = new Properties();
        prop.setProperty("java.lang.ArithmeticException", "error");
        exceptionResolver.setExceptionMappings(prop);
        exceptionResolver.setExceptionAttribute("ex");
        resolvers.add(exceptionResolver);
    }

    //配置生成模板解析器
    @Bean
    public 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
    @Bean
    public 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
    @Bean
    public ViewResolver viewResolver(SpringTemplateEngine templateEngine) {
        ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
        viewResolver.setCharacterEncoding("UTF-8");
        viewResolver.setTemplateEngine(templateEngine);
        return viewResolver;
    }
}

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    13.4 测试功能

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

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    十四、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。

    在这里插入图片描述

    ①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;
  }

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    ②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;
    }
  }

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    ③ 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) {
    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);
  }

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    14.3 DispatcherServlet 调用组件处理请求

    ① 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 {
      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);
    }
  }

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    ② doService()

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

    protected void doService(HttpServletRequest request, HttpServletResponse response) throws Exception {
    this.logRequest(request);
    Map<String, 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));
      }
    }

    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 {
      this.doDispatch(request, response);
    } finally {
      if (!WebAsyncUtils.getAsyncManager(request).isConcurrentHandlingStarted() && attributesSnapshot != null) {
        this.restoreAttributesAfterInclude(request, attributesSnapshot);
      }

      if (requestPath != null) {
        ServletRequestPathUtils.clearParsedRequestPath(request);
      }
    }
  }

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    ③ 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;
          mappedHandler = this.getHandler(processedRequest);
          if (mappedHandler == null) {
            this.noHandlerFound(processedRequest, response);
            return;
          }

          HandlerAdapter ha = this.getHandlerAdapter(mappedHandler.getHandler());
          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;
            }
          }

          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);
      }

    }
  }

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    ④ 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;
      }
    }

    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);
      }

    }
  }

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    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：

      • 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

          在这里插入图片描述

        • 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

          在这里插入图片描述

      • 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：

      • 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

    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。

    十五、SSM 整合

    15.1 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> 
 
<listener-class>org.springframework.web.context.ContextLoaderListenerlistener-class> 
listener> 
 
<context-param> 
    <param-name>contextConfigLocationparam-name> 
    <param-value>classpath:spring.xmlparam-value> 
context-param>

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    15.2 准备工作

    ①创建 Maven Module

    ②导入依赖

    
<project xmlns="http://maven.apache.org/POM/4.0.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0modelVersion>

  <groupId>com.cgg.ssmgroupId>
  <artifactId>ssmartifactId>
  <version>1.0-SNAPSHOTversion>
  <packaging>warpackaging>

  <properties>
    <maven.compiler.source>8maven.compiler.source>
    <maven.compiler.target>8maven.compiler.target>
    <spring.version>5.3.1spring.version>
  properties>


  <dependencies>
    <dependency>
      <groupId>org.springframeworkgroupId>
      <artifactId>spring-contextartifactId>
      <version>${spring.version}version>
    dependency>
    <dependency>
      <groupId>org.springframeworkgroupId>
      <artifactId>spring-beansartifactId>
      <version>${spring.version}version>
    dependency>
    
    <dependency>
      <groupId>org.springframeworkgroupId>
      <artifactId>spring-webartifactId>
      <version>${spring.version}version>
    dependency>
    <dependency>
      <groupId>org.springframeworkgroupId>
      <artifactId>spring-webmvcartifactId>
      <version>${spring.version}version>
    dependency>
    <dependency>
      <groupId>org.springframeworkgroupId>
      <artifactId>spring-jdbcartifactId>
      <version>${spring.version}version>
    dependency>
    <dependency>
      <groupId>org.springframeworkgroupId>
      <artifactId>spring-aspectsartifactId>
      <version>${spring.version}version>
    dependency>
    <dependency>
      <groupId>org.springframeworkgroupId>
      <artifactId>spring-testartifactId>
      <version>${spring.version}version>
    dependency>
    
    <dependency>
      <groupId>org.mybatisgroupId>
      <artifactId>mybatisartifactId>
      <version>3.5.7version>
    dependency>
    
    <dependency>
      <groupId>org.mybatisgroupId>
      <artifactId>mybatis-springartifactId>
      <version>2.0.6version>
    dependency>
    
    <dependency>
      <groupId>com.alibabagroupId>
      <artifactId>druidartifactId>
      <version>1.0.9version>
    dependency>
    
    <dependency>
      <groupId>junitgroupId>
      <artifactId>junitartifactId>
      <version>4.12version>
      <scope>testscope>
    dependency>
    
    <dependency>
      <groupId>mysqlgroupId>
      <artifactId>mysql-connector-javaartifactId>
      <version>8.0.16version>
    dependency>
    
    <dependency>
      <groupId>log4jgroupId>
      <artifactId>log4jartifactId>
      <version>1.2.17version>
    dependency>
    
    <dependency>
      <groupId>com.github.pagehelpergroupId>
      <artifactId>pagehelperartifactId>
      <version>5.2.0version>
    dependency>
    
    <dependency>
      <groupId>ch.qos.logbackgroupId>
      <artifactId>logback-classicartifactId>
      <version>1.2.3version>
    dependency>
    
    <dependency>
      <groupId>javax.servletgroupId>
      <artifactId>javax.servlet-apiartifactId>
      <version>3.1.0version>
      <scope>providedscope>
    dependency>
    <dependency>
      <groupId>com.fasterxml.jackson.coregroupId>
      <artifactId>jackson-databindartifactId>
      <version>2.12.1version>
    dependency>
    <dependency>
      <groupId>commons-fileuploadgroupId>
      <artifactId>commons-fileuploadartifactId>
      <version>1.3.1version>
    dependency>
    
    <dependency>
      <groupId>org.thymeleafgroupId>
      <artifactId>thymeleaf-spring5artifactId>
      <version>3.0.12.RELEASEversion>
    dependency>
  dependencies>
project>

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    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

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    15.3 配置 web.xml

    
  <filter>
    <filter-name>CharacterEncodingFilterfilter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilterfilter-class>
    <init-param>
      <param-name>encodingparam-name>
      <param-value>UTF-8param-value>
    init-param>
    <init-param>
      <param-name>forceEncodingparam-name>
      <param-value>trueparam-value>
    init-param>
  filter>
  <filter-mapping>
    <filter-name>CharacterEncodingFilterfilter-name>
    <url-pattern>/*url-pattern>
  filter-mapping>

  
  <filter>
    <filter-name>HiddenHttpMethodFilterfilter-name>
    <filter-class>org.springframework.web.filter.HiddenHttpMethodFilterfilter-class>
  filter>
  <filter-mapping>
    <filter-name>HiddenHttpMethodFilterfilter-name>
    <url-pattern>/*url-pattern>
  filter-mapping>

  
  <servlet>
    <servlet-name>SpringMVCservlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServletservlet-class>
    
    <init-param>
      <param-name>contextConfigLocationparam-name>
      <param-value>classpath:springmvc.xmlparam-value>
    init-param>
    
    <load-on-startup>1load-on-startup>
  servlet>
  <servlet-mapping>
    <servlet-name>SpringMVCservlet-name>
    <url-pattern>/url-pattern>
  servlet-mapping>

  
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListenerlistener-class>
  listener>

  
  <context-param>
    <param-name>contextConfigLocationparam-name>
    <param-value>classpath:spring.xmlparam-value>
  context-param>

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    15.4 创建 SpringMVC 的配置文件并配置

    
  <context:component-scan base-package="com.cgg.ssm.Controller">context:component-scan>

  
  <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">
          <bean class="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver">
            
            <property name="prefix" value="/WEB-INF/templates/"/>
            
            <property name="suffix" value=".html"/>
            <property name="templateMode" value="HTML5"/>
            <property name="characterEncoding" value="UTF-8" />
          bean>
        property>
      bean>
    property>
  bean>

  
  <mvc:default-servlet-handler />

  
  <mvc:annotation-driven />

  
  <mvc:view-controller path="/" view-name="index">mvc:view-controller>

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

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    15.5 搭建 MyBatis 环境

    ①创建属性文件 jdbc.properties

    jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssm
jdbc.username=root
jdbc.password=123456

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    ②创建 MyBatis 的核心配置文件 mybatis-config.xml

    
DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>

  <settings>
    
    <setting name="logImpl" value="STDOUT_LOGGING"/>
    
    <setting name="mapUnderscoreToCamelCase" value="true"/>
  settings>

  <plugins>
    
    <plugin interceptor="com.github.pagehelper.PageInterceptor">plugin>
  plugins>
configuration>

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    ③创建 Mapper 接口和映射文件

    public interface EmployeeMapper {
  public List<Employee> getAllEmployee();
}
<mapper namespace="com.cgg.ssm.mapper.EmployeeMapper">
  <!--填写映射-->
<!--  public List<Employee> getAllEmployee();-->
  <select id="getAllEmployee" resultType="Employee">
    select * from t_emp
  </select>
</mapper>

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    ④创建日志文件 log4j.xml

    
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>

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    15.6 创建 Spring 的配置文件并配置

    
<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"
  xmlns:tx="http://www.springframework.org/schema/tx"
  xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

  
  <context:component-scan base-package="com.cgg.ssm">
    <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
  context:component-scan>

  
  <context:property-placeholder location="classpath:jdbc.properties">context:property-placeholder>

  
  <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>

  
  <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    <property name="dataSource" ref="dataSource">property>
  bean>

  
  <tx:annotation-driven transaction-manager="transactionManager">tx:annotation-driven>

  
  <bean class="org.mybatis.spring.SqlSessionFactoryBean">
    
    <property name="configLocation" value="classpath:mybatis-config.xml">property>
    
    <property name="dataSource" ref="dataSource">property>
    
    <property name="typeAliasesPackage" value="com.cgg.ssm.pojo">property>
    
    
  bean>

  
  <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="com.cgg.ssm.mapper">property>
  bean>
beans>

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    15.7 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 gender;

    private String email;

    public Employee() {
    }

    public Employee(Integer empId, String empName, Integer age, String gender, String email) {
        this.empId = empId;
        this.empName = empName;
        this.age = age;
        this.gender = gender;
        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 getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public String toString() {
        return "Employee{" +
                "empId=" + empId +
                ", empName='" + empName + '\'' +
                ", age=" + age +
                ", gender='" + gender + '\'' +
                ", email='" + email + '\'' +
                '}';
    }
}

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    创建控制层组件EmployeeController

    @Controller
public class EmployeeController {

  @Autowired
  private EmployeeService employeeService;

  @RequestMapping(value = "/employee",method = RequestMethod.GET)
  public String getAllEmployee(Model model){
    List<Employee> list = employeeService.getAllEmployee();
    System.out.println("EmployeeController................");
    model.addAttribute("list", list);
    return "employ_list";
  }
}

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    创建接口EmployeeService

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

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    创建实现类EmployeeServiceImpl

    @Controller
public class EmployeeController {

  @Autowired
  private EmployeeService employeeService;
///employee/page/1
  @RequestMapping(value = "/employee/page/{pageNum}",method = RequestMethod.GET)
  public String getEmployeePage(@PathVariable("pageNum") Integer pageNum,Model model){
    PageInfo<Employee> page = employeeService.getEmployeePage(pageNum);
    model.addAttribute("page", page);
    return "employ_list";
  }

  @RequestMapping(value = "/employee",method = RequestMethod.GET)
  public String getAllEmployee(Model model){
    List<Employee> list = employeeService.getAllEmployee();
    System.out.println("EmployeeController................");
    model.addAttribute("list", list);
    return "employ_list";
  }
}

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    ②创建页面

    DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
  <meta charset="UTF-8">
  <title>员工列表title>
  <link rel="stylesheet" th:href="@{/static/css/index_work.css}">
head>
<body>
<table>
  <tr>
    <th colspan="6">员工列表th>
  tr>
  <tr>
    <th>流水号th>
    <th>员工姓名th>
    <th>年龄th>
    <th>性别th>
    <th>邮箱th>
    <th>操作th>
  tr>
  <tr th:each="employee,status : ${page.list}">
    <td th:text="${status.count}">td>
    <td th:text="${employee.empName}">td>
    <td th:text="${employee.age}">td>
    <td th:text="${employee.gender}">td>
    <td th:text="${employee.email}">td>
    <td>
      <a href="">删除a>
      <a href="">修改a>
    td>
  tr>
table>
<div style="text-align: center;">
  <a th:if="${page.hasPreviousPage}" th:href="@{/employee/page/1}">首页a>
  <a th:if="${page.hasPreviousPage}" th:href="@{'/employee/page/'+${page.prePage}}">上一页a>
  <span th:each="num : ${page.navigatepageNums}">
        <a th:if="${page.pageNum == num}" style="color: red;" th:href="@{'/employee/page/'+${num}}" th:text="'['+${num}+']'">a>
        <a th:if="${page.pageNum != num}" th:href="@{'/employee/page/'+${num}}" th:text="${num}">a>
    span>
  <a th:if="${page.hasNextPage}" th:href="@{'/employee/page/'+${page.nextPage}}">下一页a>
  <a th:if="${page.hasNextPage}" th:href="@{'/employee/page/'+${page.pages}}">末页a>
div>
body>
html>

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    ③访问测试分页功能

    localhost:8080/employee/page/1

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  • 原文地址：https://blog.csdn.net/weixin_42200347/article/details/126456382