spring-mvc 系列：注解开发（SpringMVCConfig、SpringConfig、AbstractAnnotationConfigDispatcherServletInitializer详细配置）

阅读原文时间：2023年08月11日阅读：5

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SpringMVC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.mcode.api.config;

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

import javax.servlet.Filter;

/**
 * ClassName: WebInit
 * Package: com.mcode.api.config
 * Description:
 *
 * @Author robin
 * @Create 2023/8/10 21:24
 * @Version 1.0
 */
public class WebInit extends AbstractAnnotationConfigDispatcherServletInitializer {

    /**
     * 指定spring的配置类
     * @return
     */
    protected Class<?>[] getRootConfigClasses() {
        return new Class[]{SpringConfig.class};
    }

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

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

    /**
     * 注册过滤器
     * @return
     */
    @Override
    protected Filter[] getServletFilters() {
        CharacterEncodingFilter encodingFilter = new CharacterEncodingFilter();
        encodingFilter.setEncoding("UTF-8");
        encodingFilter.setForceEncoding(true);
        HiddenHttpMethodFilter hiddenHttpMethodFilter = new HiddenHttpMethodFilter();
        return  new Filter[] {hiddenHttpMethodFilter,encodingFilter};
    }
}

二、创建SpringConfig配置类，代替Spring的配置文件

package com.mcode.api.config;

import org.springframework.context.annotation.Configuration;

/**
 * ClassName: SpringConfig
 * Package: com.mcode.api.config
 * Description:
 *
 * @Author robin
 * @Create 2023/8/10 21:25
 * @Version 1.0
 */
@Configuration
public class SpringConfig {
    //ssm整合之后，spring的配置信息写在此类中
}

三、创建SpringMVC配置类，代替SpringMVC的配置文件

package com.mcode.api.config;

import com.mcode.api.interceptors.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;

/**
 * ClassName: SpringMVCConfig
 * Package: com.mcode.api.config
 * Description:
 *
 * @Author robin
 * @Create 2023/8/10 21:26
 * @Version 1.0
 */

/**
 * 代替SpringMVC的配置文件：
 * 1、扫描组件   2、视图解析器     3、view-controller    4、default-servlet-handler
 * 5、mvc注解驱动    6、文件上传解析器   7、异常处理      8、拦截器
 */

//将当前类标识为一个配置类
@Configuration
//1.扫描组件
@ComponentScan("com.mcode.api.controller")
//5.开启MVC注解驱动
@EnableWebMvc
public class SpringMVCConfig implements WebMvcConfigurer {

    /**
     * 使用默认的servlet处理静态资源
     * 4、default-servlet-handler
     * @param configurer
     */
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    /**
     * 6.配置文件上传解析器
     * @return
     */
    @Bean
    public CommonsMultipartResolver multipartResolver(){
        return  new CommonsMultipartResolver();
    }

    /**
     * 8.配置拦截器
     * @param registry
     */
    public void addInterceptors(InterceptorRegistry registry) {
        FirstInterceptor interceptor = new FirstInterceptor();
        registry.addInterceptor(interceptor).addPathPatterns("/**");
    }

    /**
     * 3.配置视图控制,view-controller
     * @param registry
     */
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("index");
    }

    /**
     * 7、异常处理
     * @param resolvers
     */
    public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
        SimpleMappingExceptionResolver exceptionResolver = new SimpleMappingExceptionResolver();
        Properties properties   = new Properties();
        properties.setProperty("java.lang.ArithmeticException", "error");
        exceptionResolver.setExceptionMappings(properties);
        exceptionResolver.setExceptionAttribute("ex");
        resolvers.add(exceptionResolver);
    }

    /**
     * 配置生成模板解析器
     * @return
     */
    @Bean
    public ITemplateResolver templateResolver(){
        WebApplicationContext context = ContextLoader.getCurrentWebApplicationContext();
        ServletContextTemplateResolver templateResolver = new ServletContextTemplateResolver(context.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
     * @param templateResolver
     * @return
     */
    @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
     * @param templateEngine
     * @return
     */
    @Bean
    public ViewResolver viewResolver(SpringTemplateEngine templateEngine){
        ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
        viewResolver.setCharacterEncoding("UTF-8");
        viewResolver.setTemplateEngine(templateEngine);
        return viewResolver;
    }
}

四、测试功能

index.html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>首页</title>
</head>
<body>
<h1>首页</h1>
<a th:href="@{/testAnnotation}">测试注解</a>
</body>
</html>

error.html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>error</title>
</head>
<body>
<h1>错误页面</h1>
<p th:text="${ex}"></p>
</body>
</html>

success.html

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

TestController

package com.mcode.api.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

/**
 * ClassName: TestController
 * Package: com.mcode.api.controller
 * Description:
 *
 * @Author robin
 * @Create 2023/8/10 21:23
 * @Version 1.0
 */
@Controller
public class TestController {

    @RequestMapping("/testAnnotation")
    public String testAnnotation() {
        System.out.println(1 / 0);
        return "success";
    }
}

FirstInterceptor

package com.mcode.api.interceptors;

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

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

/**
 * ClassName: FirstInterceptor
 * Package: com.mcode.api.interceptors
 * Description:
 *
 * @Author robin
 * @Create 2023/8/10 21:35
 * @Version 1.0
 */
public class FirstInterceptor implements HandlerInterceptor {
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("FirstInterceptor.preHandle");
        return true;
    }

    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("FirstInterceptor.postHandle");
    }

    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("FirstInterceptor.afterCompletion");
    }
}

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