目录

一、创建初始化类，代替web.xml

二、创建SpringConfig配置类，代替spring的配置文件

三、创建WebConfig配置类，代替SpringMVC的配置文件

四、测试功能

使用配置类和注解代替web.xml和SpringMVC配置文件的功能

一、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现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。

package com.atguigu.config;

import org.springframework.web.filter.CharacterEncodingFilter;
import org.springframework.web.filter.HiddenHttpMethodFilter;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

import javax.servlet.Filter;

/**
 * 用来代替web.xml
 */

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};
    }
}

二、创建SpringConfig配置类，代替spring的配置文件

import org.springframework.context.annotation.Configuration;

/**
 * 代替Spring的配置文件
 */

//ssm整合之后，spring的配置信息写在此类中
@Configuration//将类标识为配置类
public class SpringConfig {
}

三、创建WebConfig配置类，代替SpringMVC的配置文件

package com.atguigu.config;

import com.atguigu.interceptor.FirstInterceptor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.context.ContextLoader;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.*;
import org.springframework.web.servlet.handler.SimpleMappingExceptionResolver;
import org.thymeleaf.spring5.SpringTemplateEngine;
import org.thymeleaf.spring5.view.ThymeleafViewResolver;
import org.thymeleaf.templatemode.TemplateMode;
import org.thymeleaf.templateresolver.ITemplateResolver;
import org.thymeleaf.templateresolver.ServletContextTemplateResolver;

import java.util.List;
import java.util.Properties;

/**
 * 代替SpringMVC的配置文件:
 * 扫描（控制层）组件、（Thymeleaf）视图解析器、
 * 默认的servlet（处理静态资源）、（开启）mvc的注解驱动
 * 视图控制器（view-controller）、文件上传解析器、拦截器、异常解析器
 */

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

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

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

    //文件上传解析器
    @Bean
    //@Bean注解可以将标识的方法的返回值作为bean，bean的id为方法的方法名
    public CommonsMultipartResolver multipartResolver(){
        return new CommonsMultipartResolver();
    }

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

    //异常解析器
    @Override
    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;
    }
}

创建FirstInterceptor 

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class FirstInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }
}

四、测试功能

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>首页</title>
</head>
<body>
    <h1>index.html</h1>
</body>
</html>