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();
    }

}