注解方式配置SpringMVC

1. 初始化类，代替web.xml

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.xml文件

<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    
    <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>

    
    <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>

web-app>

初始化类代替web.xml

/**
 * 创建初始化类，代替web.xml
 */
public class WebInit extends AbstractAnnotationConfigDispatcherServletInitializer {
    @Override
    // 指定Spring的配置类
    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{SpringConfig.class};
    }

    @Override
    // 加载SpringMVC的配置类
    protected Class<?>[] getServletConfigClasses() {
        return new Class[]{SpringMVCConfig.class};
    }

    @Override
    // 指定DispatcherServlet的映射规则,即url-pattern
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }

    @Override
    // 添加过滤器--> web.xml中一般存在两个编码顾虑去和put,post请求过滤器
    protected Filter[] getServletFilters() {
        CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();
        characterEncodingFilter.setEncoding("UTF-8");
        characterEncodingFilter.setForceEncoding(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表示该类为配置文件类

@Configuration
public class SpringConfig {
//ssm整合之后，spring的配置信息写在此类中
}

3. 创建SpringMVCConfig配置类，代替SpringMVC.xml配置文件

springmvc.xml配置文件内容：

1. 扫描组件
2. 文件上传解析器
3. 视图解析器themeleaf
4. 默认的servlet
5. mvc的注解启动
6. 视图控制器
7. 拦截器（无）
8. 异常解析器（无）

<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:aop="http://www.springframework.org/schema/aop" xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans  http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
           http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
           http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd">

       <context:component-scan base-package="com.lsm.controller">context:component-scan>

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

        
        <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:annotation-driven />
       
       <mvc:default-servlet-handler/>
       <mvc:view-controller path="/" view-name="index" />

beans>

创建SpringMVCConfig配置类，代替SpringMVC.xml配置文件，需要实现WebMvcConfigurer 接口

/**
 * SpringMVC配置文件中可以配置的内容：
 * 1. 扫描组件---
 * 2. 文件上传解析器---
 * 3. 视图解析器themeleaf---
 * 4. 默认的servlet----
 * 5. mvc的注解启动---
 * 6. 视图控制器---
 * 7. 拦截器---
 * 8. 异常解析器
 */

@Configuration
@ComponentScan("qc.lsm.controller")  // 对应1: 扫描组件
@EnableWebMvc  // 对应5: mvc的注解驱动
public class SpringMVCConfig implements WebMvcConfigurer {


    @Override
    // 对应6: 视图控制器
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("index");
    }

    @Override
    // 对应4: 默认视图servlet
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    @Bean
    // 对应2: 文件解析器
    public CommonsMultipartResolver getMultipartResolver(){
        return new CommonsMultipartResolver();
    }

    @Override
    // 对应7: 拦截器
    public void addInterceptors(InterceptorRegistry registry) {
        FirstInterceptor firstInterceptor = new FirstInterceptor();
        registry.addInterceptor(firstInterceptor);
    }


    // 对应3: 视图解析器
    // 配置生成模板解析器
    @Bean
    public ITemplateResolver templateResolver() {
        WebApplicationContext webApplicationContext = ContextLoader.getCurrentWebApplicationContext();
        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;
    }

}

4. 项目结构