13、注解配置springmvc

使用配置类和注解代替web.xml和SpringMVC配置文件的功能

13.1、创建初始化的类，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。

13.2、使用流程

1. 声明一个类来继承AbstractAnnotationConfigDispatcherServletInitializer，并且实现他的抽象方法

2. 实现配置SpringConfig的java文件

   @Override
       protected Class<?>[] getRootConfigClasses() {
           return new Class[]{SpringConfig.class};
       }
   

3. 实现SpringMvcConfig的java文件

   @Override
   protected Class<?>[] getServletConfigClasses() {
       return new Class[]{SpringMvcConfig.class};
   }
   

13.3、实例代码

1.继承AbstractAnnotationConfigDispatcherServletInitializer的java文件

/**
 * @author ning0
 * @date 2024/6/25 22:24
 * @description WebInit
 */
public class WebInit extends AbstractAnnotationConfigDispatcherServletInitializer {

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

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

    //设置DispatcherServlet的url-pattern
    @Override
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }

    @Override
    protected Filter[] getServletFilters() {

        // 创建编码过滤器
        CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();
        // 设置编码格式
        characterEncodingFilter.setEncoding("UTF-8");
        // 设置强制编码
        characterEncodingFilter.setForceEncoding(true);

        // 创建请求方式的过滤器
        HiddenHttpMethodFilter hiddenHttpMethodFilter = new HiddenHttpMethodFilter();

        return new Filter[]{characterEncodingFilter, hiddenHttpMethodFilter};
    }
}

2.SpringMvcConfig.java文件

package com.qc.config;

import com.qc.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.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 javax.servlet.ServletContext;
import java.util.List;
import java.util.Properties;

/**
 * @author ning0
 * @date 2024/6/25 22:27
 * @description SpringMvcConfig
 */
// 配置类
@Configuration
// 扫描controller
@ComponentScan("com.qc.controller")
// 开启SpringMvc注解
@EnableWebMvc
public class SpringMvcConfig implements WebMvcConfigurer {

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


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

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

    // 异常解析器
    @Override
    public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
        SimpleMappingExceptionResolver simpleMappingExceptionResolver = new SimpleMappingExceptionResolver();
        Properties properties = new Properties();
        properties.setProperty("java.lang.ArithmeticException", "error");
        simpleMappingExceptionResolver.setExceptionMappings(properties);
        simpleMappingExceptionResolver.setExceptionAttribute("ex");
        resolvers.add(simpleMappingExceptionResolver);

    }


    // 配置视图解析器
    @Bean
    public ITemplateResolver templateResolver() {
        WebApplicationContext webApplicationContext = ContextLoader.getCurrentWebApplicationContext();
        ServletContextTemplateResolver templateResolver = new ServletContextTemplateResolver(webApplicationContext.getServletContext());
        templateResolver.setPrefix("/WEB-INF/pages/");
        templateResolver.setSuffix(".html");
        templateResolver.setCharacterEncoding("UTF-8");
        templateResolver.setTemplateMode(TemplateMode.HTML);
        return templateResolver;
    }


    // 配置模板引擎
    @Bean
    public SpringTemplateEngine templateEngine(ITemplateResolver templateResolver) {
        SpringTemplateEngine templateEngine = new SpringTemplateEngine();
        templateEngine.setTemplateResolver(templateResolver);
        return templateEngine;
    }


    // 配置视图解析器注入引擎
    @Bean
    public ViewResolver viewResolver(SpringTemplateEngine templateEngine) {
        ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
        viewResolver.setCharacterEncoding("UTF-8");
        viewResolver.setTemplateEngine(templateEngine);
        return viewResolver;
    }


}

3.SpringConfig.java

package com.qc.config;

import org.springframework.context.annotation.Configuration;

/**
 * @author ning0
 * @date 2024/6/25 22:26
 * @description SpringConfig
 */

//将该类标注为配置类
@Configuration
public class SpringConfig {

}

g.springframework.context.annotation.Configuration;

/**

• @author ning0
• @date 2024/6/25 22:26
• @description SpringConfig
  */

//将该类标注为配置类
@Configuration
public class SpringConfig {

}