SpringMVC-基于注解开发

　　　　　　　　　　　　　　　　注解配置SpringMVC

　　1.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.hrf.Config;

import com.hrf.Interceptor.TestInterceptor;
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.MultipartResolver;
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;

//用来代替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
//@Configuration是将当前类标识为一个配置类
@Configuration
//1.扫描组件
@ComponentScan("com.hrf.controller")
//5.mvc注解驱动
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {

    //4.default-servlet-handler处理静态资源
    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    // 8.拦截器
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        TestInterceptor testInterceptor = new TestInterceptor();
        registry.addInterceptor(testInterceptor).addPathPatterns("/**");
    }
    //3，view-controller
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/hello").setViewName("hello");
    }
        // 6.文件上传解析器
        @Bean
        public MultipartResolver multipartResolver(){
            CommonsMultipartResolver commonsMultipartResolver = new CommonsMultipartResolver();
            return commonsMultipartResolver;
        }
    //7.异常处理
    @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;
    }

}