基于XML搭建SpringMVC项目

*如果你需要将应用部署到不支持Servlet3.0容器中 或者 你只是对web.xml情有独钟，那我们只能按照传统的方式，通过web.xml来配置SpringMVC。

*搭建SpringMVC需要在web.xml中注册DispatcherServlet和ContextLoaderListener，同时他们两个之间会分别通过上下文参数contextConfigLocation指定一个XML文件地址来加载Spring应用上下文，而我更倾向于使用Java配置类来加载Spring应用上下文（本文也是如此）。

（1）pom中添加SpringMVC相关jar

     <dependency>
       <groupId>org.springframework</groupId>
       <artifactId>spring-webmvc</artifactId>
       <version>4.3.21.RELEASE</version>
     </dependency>

（2）设置web.xml文件（使用Java配置类来加载Spring应用上下文）

*要在SpringMVC中使用Java配置类来构建Spring应用上下文，我们需要配置DispatcherServlet和ContextLoaderListener的contextClass上下文参数为AnnotationConfigWebApplicationContext，AnnotationConfigWebApplicationContext是WebApplicationContext的实现类，它会加载Java配置类而不是XML文件

 <?xml version="1.0" encoding="UTF-8"?>
 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xmlns="http://java.sun.com/xml/ns/javaee"
          xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
          id="WebApp_ID" version="2.5">
     <!--指定根配置使用Java配置类-->
     <context-param>
         <param-name>contextClass</param-name>
         <param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value>
     </context-param>
     <!--指定根配置Java配置类所在路径-->
     <context-param>
         <param-name>contextConfigLocation</param-name>
         <param-value>cn.coreqi.config.RootConfig</param-value>
     </context-param>
     <!--注册ContextLoaderListener-->
     <listener>
         <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
     </listener>
     <!--注册DispatcherServlet-->
     <servlet>
         <servlet-name>dispatcherServlet</servlet-name>
         <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
         <!--指定DispatcherServlet配置使用Java配置类-->
         <init-param>
             <param-name>contextClass</param-name>
             <param-value>org.springframework.web.context.support.AnnotationConfigWebApplicationContext</param-value>
         </init-param>
         <!--指定DispatcherServlet配置Java配置类所在路径-->
         <init-param>
             <param-name>contextConfigLocation</param-name>
             <param-value>cn.coreqi.config.WebConfig</param-value>
         </init-param>
         <!--这是启动优先级吧-->
         <load-on-startup>1</load-on-startup>
     </servlet>
     <!--DispatcherServlet映射-->
     <servlet-mapping>
         <servlet-name>dispatcherServlet</servlet-name>
         <url-pattern>/</url-pattern>
     </servlet-mapping>
 </web-app>

（3）根配置类（初始化项目，所以没啥内容）

 package cn.coreqi.config;

 import org.springframework.context.annotation.Configuration;

 @Configuration
 public class RootConfig {
 }

（4）DispatcherServlet配置类

 package cn.coreqi.config;

 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.config.annotation.*;
 import org.thymeleaf.TemplateEngine;
 import org.thymeleaf.spring4.SpringTemplateEngine;
 import org.thymeleaf.spring4.templateresolver.SpringResourceTemplateResolver;
 import org.thymeleaf.spring4.view.ThymeleafViewResolver;
 import org.thymeleaf.templatemode.TemplateMode;
 import org.thymeleaf.templateresolver.ITemplateResolver;

 @Configuration
 @EnableWebMvc   //启用Spring MVC 注解驱动  <mvc:annotation-driven />
 @ComponentScan("cn.coreqi.controller")
 public class WebConfig extends WebMvcConfigurerAdapter {

     //配置Thymeleaf视图解析器
     @Bean
     public ViewResolver viewResolver(TemplateEngine templateEngine){
         ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
         viewResolver.setTemplateEngine(templateEngine);
         viewResolver.setCharacterEncoding("utf-8");
         return viewResolver;
     }

     //创建模板引擎
     @Bean
     public TemplateEngine templateEngine(ITemplateResolver templateResolver){
         SpringTemplateEngine templateEngine = new SpringTemplateEngine();
         templateEngine.setTemplateResolver(templateResolver);
         return templateEngine;
     }

     //创建Thymeleaf模板解析器
     @Bean
     public ITemplateResolver templateResolver(){
         SpringResourceTemplateResolver resolver = new SpringResourceTemplateResolver();
         resolver.setPrefix("/WEB-INF/templates/");
         resolver.setSuffix(".html");
         resolver.setTemplateMode(TemplateMode.HTML);
         resolver.setCacheable(false);
         resolver.setCharacterEncoding("utf-8");
         return resolver;
     }

     //配置对静态资源的处理
     @Override
     public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
         configurer.enable();
     }

 }