目錄

一、創建初始化類，代替web.xml

二、創建SpringConfig配置類，代替spring的配置文件

三、創建WebConfig配置類，代替SpringMVC的配置文件

四、測試功能

使用配置類和注解代替web.xml和SpringMVC配置文件的功能

一、創建初始化類，代替web.xml

• 在Servlet3.0環境中，容器會在類路徑中查找實現javax.servlet.ServletContainerInitializer接口的類， 如果找到的話就用它來配置Servlet容器。
• Spring提供了這個接口的實現，名為 SpringServletContainerInitializer，這個類反過來又會查找實現WebApplicationInitializer的類并將配置的任務交給它們來完成。
• Spring3.2引入了一個便利的WebApplicationInitializer基礎實現，
• 名為 AbstractAnnotationConfigDispatcherServletInitializer，
• 當我們的類擴展了 AbstractAnnotationConfigDispatcherServletInitializer并將其部署到Servlet3.0容器的時候，容器會自動發現它，并用它來配置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;

/**
 * 用來代替web.xml
 */

public class WebInit extends AbstractAnnotationConfigDispatcherServletInitializer {
    @Override
    //設置一個配置類，代替Spring的配置文件
    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{SpringConfig.class};
    }

    @Override
    //設置一個配置類，代替SpringMVC的配置文件
    protected Class<?>[] getServletConfigClasses() {
        return new Class[]{WebConfig.class};
    }

    @Override
    //設置SpringMVC的前端控制器DispatcherServlet的url-pattern
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }

    @Override
    //設置當前的過濾器
    protected Filter[] getServletFilters() {
        //創建編碼過濾器
        CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();
        characterEncodingFilter.setEncoding("UTF-8");
        characterEncodingFilter.setForceEncoding(true);
        //創建處理請求方式的過濾器
        HiddenHttpMethodFilter hiddenHttpMethodFilter = new HiddenHttpMethodFilter();
        return new Filter[]{characterEncodingFilter,hiddenHttpMethodFilter};
    }
}

二、創建SpringConfig配置類，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的配置信息寫在此類中
@Configuration//將類標識為配置類
public class SpringConfig {
}

三、創建WebConfig配置類，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:
 * 掃描（控制層）組件、（Thymeleaf）視圖解析器、
 * 默認的servlet（處理靜態資源）、（開啟）mvc的注解驅動
 * 視圖控制器（view-controller）、文件上傳解析器、攔截器、異常解析器
 */

@Configuration//將類標識為配置類
@ComponentScan("com.atguigu.controller")//掃描組件
@EnableWebMvc//開啟mvc的注解驅動
public class WebConfig implements WebMvcConfigurer {

    @Override
    //默認的servlet處理靜態資源
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

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

    //文件上傳解析器
    @Bean
    //@Bean注解可以將標識的方法的返回值作為bean，bean的id為方法的方法名
    public CommonsMultipartResolver multipartResolver(){
        return new CommonsMultipartResolver();
    }

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

    //異常解析器
    @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需要一個ServletContext作為構造參數，可通過
// WebApplicationContext 的方法獲得
        ServletContextTemplateResolver templateResolver = new
                ServletContextTemplateResolver(
                webApplicationContext.getServletContext());
        templateResolver.setPrefix("/WEB-INF/templates/");
        templateResolver.setSuffix(".html");
        templateResolver.setCharacterEncoding("UTF-8");
        templateResolver.setTemplateMode(TemplateMode.HTML);
        return templateResolver;
    }
    //生成模板引擎并為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;
    }
    //生成視圖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;
    }
}

創建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、測試功能

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

?