五.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

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.ServletContainerlnitializer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SpringServletContainerlnitializer,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 WebApplicationlnitializer基t础实现，名为AbstractAnnotationConfigDispatcherServletlnitializer,当我们的类 扩展了AbstractAnnotationConfigDispatcherServletlnitializer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。

public class WebInit extends AbstractAnnotationConfigDispatcherServletInitializer {

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

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

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

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

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

2、创建SpringConfigi配置类，代替spring的配置文件

@Configuration
public class SpringConfig {
    //ssm整合之后，spring的配置信息写在此类中
}

3、创建WebConfigi配置类，代替SpringMVC的配置文件

/**
 * 代替SpringMVC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
//5.mvc注解驱动
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {

    //使用默认的serv1et处理静态资源
    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }

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

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

    //配置视图控制

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

    //配置异映射
    @Override
    public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
        SimpleMappingExceptionResolver resolver = new SimpleMappingExceptionResolver();
        Properties prop = new Properties();
        prop.setProperty("java.lang.ArithmeticException", "error");
        //设置异常映射
        resolver.setExceptionMappings(prop);
        //设置共享异常信息的键
        resolver.setExceptionAttribute("ex");
        resolvers.add(resolver);
    }

    //配置生成器模板
    @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(".htm1");
        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;
    }
}

4、测试功能

@RequestMapping("/")
public String index(){
    return "index";
}