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

<?xml version="1.0" encoding="UTF-8"?>
<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"><!--配置前端控制器DispatcherServlet--><servlet><servlet-name>springmvc</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><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>springmvc</servlet-name><url-pattern>/</url-pattern></servlet-mapping><!--乱码过滤器--><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><!--put,post请求方式--><filter><filter-name>HiddenHttpMethodFilter</filter-name><filter-class>org.springframework.web.filter.HiddenHttpMethodFilter</filter-class></filter><filter-mapping><filter-name>HiddenHttpMethodFilter</filter-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-patternprotected 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）

<?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"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.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsdhttp://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><!--上传文件, id名必须为multipartResolver--><bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"></bean><!-- 配置Thymeleaf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"><bean class="org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver"><!--/WEB-INF/templates/xxx.html--><!-- 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><!--配置默认首页, 开启mvc的注解驱动--><mvc:annotation-driven /><!--配置默认的servlet处理静态资源，浏览器发送的请求会被DispatcherServlet处理，无法处理再交给DefaultServlet处理--><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servletpublic 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@Beanpublic ITemplateResolver templateResolver() {WebApplicationContext webApplicationContext = ContextLoader.getCurrentWebApplicationContext();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(ITemplateResolvertemplateResolver) {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;}}

4. 项目结构