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。

public class WebInit extends AbstractAnnotationConfigDispatcherServletInitializer {
 
    /**
     * 指定 spring 的配置类
     *
     * @return 返回值为一个 spring 配置类数组
     */
    @Override
    protected Class[] getRootConfigClasses() {
        return new Class[]{SpringConfig.class};
    }
 
    /**
     * 指定 SpringMVC 的配置类
     *
     * @return 返回值为一个 SpringMVC 配置类数组
     */
    @Override
    protected Class[] getServletConfigClasses() {
        return new Class[]{WebConfig.class};
    }
 
    /**
     * 指定 DispatcherServlet 的映射规则，即url-pattern
     *
     * @return 返回值为一个字符串（url-pattern）数组
     */
    @Override
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }
 
    /**
     * 添加过滤器
     *
     * @return 返回值为 过滤器对象 数组
     */
    @Override
    protected Filter[] getServletFilters() {
        // 设置编码过滤器
        CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();
        characterEncodingFilter.setEncoding("UTF-8");
        characterEncodingFilter.setForceEncoding(true);
 
        // 设置请求过滤器
        HiddenHttpMethodFilter hiddenHttpMethodFilter = new HiddenHttpMethodFilter();
        return new Filter[]{characterEncodingFilter, hiddenHttpMethodFilter};
    }
}

2、创建SpringConfig配置类，代替spring的配置文件

/**
 * 代替spring的配置文件
 */
@Configuration // 声明配置类
public class SpringConfig {
    //ssm整合之后，spring的配置信息写在此类中
}

3、创建WebConfig配置类，代替SpringMVC的配置文件

/**
 * 代替SpringMVC的配置文件
 * 组件扫描，视图解释器,默认的Servlet,MVC注解驱动,
 * 视图控制器,文件上传解析器,拦截器,异常解析器
 */
@Configuration // 声明配置类
@ComponentScan("com.chenyixin.ssm")
@EnableWebMvc // 开启MVC注解驱动
public class WebConfig implements WebMvcConfigurer {
 
    /**
     * 使用默认的servlet处理静态资源
     *
     * @param configurer
     */
    @Override
    public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }
 
    /**
     * 文件上传解析器
     *
     * @return
     */
    @Bean //@Bean 注解可以将标识的方法的返回值作为 bean 进行管理
    public CommonsMultipartResolver multipartResolver() {
        return new CommonsMultipartResolver();
    }
 
    /**
     * 配置视图控制器
     *
     * @param registry
     */
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("index");
    }
 
    /**
     * 配置拦截器
     *
     * @param registry
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        FirstInterceptor firstInterceptor = new FirstInterceptor();
        registry.addInterceptor(firstInterceptor).addPathPatterns("/**")
                .excludePathPatterns("/aaa");
    }
 
    /**
     * 配置异常映射
     *
     * @param resolvers
     */
    @Override
    public void configureHandlerExceptionResolvers(List resolvers) {
        SimpleMappingExceptionResolver exceptionResolver = new SimpleMappingExceptionResolver();
        Properties prop = new Properties();
        prop.setProperty("java.lang.ArithmeticException", "error");
        //设置异常映射
        exceptionResolver.setExceptionMappings(prop);
 
        // 设置共享异常信息的键
        exceptionResolver.setExceptionAttribute("ex");
        resolvers.add(exceptionResolver);
    }
 
    /**
     * 以下配置视图解析器
     * @return
     */
 
    // 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;
    }
}

过滤器：

 
public class FirstInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("FirstInterceptor --> preHandle");
        return true;
    }
 
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("FirstInterceptor --> postHandle");
 
    }
 
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("FirstInterceptor --> afterCompletion");
 
    }
}

4、测试功能（资源代码）

index.html:

html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>首页title>
head>
<body>
<h1>Indexh1>
<a th:href="@{/test/hello}">测试a>
body>
html>

success.html:

html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>成功title>
head>
<body>
<h1>successh1>
body>
html>

error.html:

html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>成功title>
head>
<body>
<h1>successh1>
body>
html>

conttoller层代码:

@Controller
public class TestController {
 
    @RequestMapping("test/hello")
    public String hello() {
        // System.out.println(1/0);
        return "success";
    }
 
}