SpringMVC-配置类和注解

一、介绍
利用配置类和注解来代替web.xml和SpringMVC-config.xml文件

二、项目测试
（1）创建继承了AbstractAnnotationConfigDispatcherServletInitializer的类，该类可以配置DispatcherServlet、过滤器、监听器、Spring配置类、SpringMVC配置类。

public class WebInit extends AbstractAnnotationConfigDispatcherServletInitializer {

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

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

    //指定DispatcherServlet的映射规则
    @Override
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }

    //配置过滤器
    @Override
    protected Filter[] getServletFilters() {
        CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();
        characterEncodingFilter.setEncoding("UTF-8");
        characterEncodingFilter.setForceResponseEncoding(true);
        HiddenHttpMethodFilter hiddenHttpMethodFilter = new HiddenHttpMethodFilter();
        hiddenHttpMethodFilter.setMethodParam("_method");
        return new Filter[]{characterEncodingFilter, hiddenHttpMethodFilter};
    }
}

（2）创建SpringConfig类，用于整合其他框架使用

@Configuration
public class SpringConfig {

}

（3）创建WebConfig类，作为SpringMVC的配置类，用于开启组件扫描，配置视图解析器Bean。该类实现WebMvcConfigurer接口后，可以配置注解驱动、静态资源处理（DefaultServlet）、视图控制器、拦截器、异常处理器

@Configuration
@ComponentScan("com.wsh.controller")
@EnableWebMvc //开启注解驱动
public class WebConfig implements WebMvcConfigurer {

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

    //将模板解析器注入模板引擎
    @Bean
    public SpringTemplateEngine templateEngine(ITemplateResolver templateResolver){
        SpringTemplateEngine templateEngine = new SpringTemplateEngine();
        templateEngine.setTemplateResolver(templateResolver);
        return templateEngine;
    }

    //将模板引擎注入Thymeleaf视图解析器
    @Bean
    public ViewResolver viewResolver(SpringTemplateEngine templateEngine){
        ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
        viewResolver.setTemplateEngine(templateEngine);
        viewResolver.setCharacterEncoding("UTF-8");
        return viewResolver;
    }

    //开启DefaultServlet来处理静态资源
    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

    //添加拦截器
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new FirstInterceptor()).addPathPatterns("/**");
        registry.addInterceptor(new SecondInterceptor()).addPathPatterns("/**");
    }

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

    //添加异常处理器
    @Override
    public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
        SimpleMappingExceptionResolver exceptionResolver = new SimpleMappingExceptionResolver();
        Properties properties = new Properties();
        properties.setProperty("java.lang.ArithmeticException", "forward:error");
        exceptionResolver.setExceptionMappings(properties);
        exceptionResolver.setExceptionAttribute("ex");
        resolvers.add(exceptionResolver);
    }
}