Spring Boot----SpringBoot中SpringMVC配置原理

官方文档

29.1.1 Spring MVC Auto-configuration

Spring Boot provides auto-configuration for Spring MVC that works well with most applications.

The auto-configuration adds the following features on top of Spring’s defaults:

• Inclusion of ContentNegotiatingViewResolver and BeanNameViewResolver beans.
  • 自动配置ViewResolver（视图解析器：根据方法的返回值获得视图对象(View)，视图对象决定如何渲染（转发？重定向？））
  • ContentNegotiatingViewResolver组合了所有的视图解析器
  • 如何定制？我们只需要给容器添加一个视图解析器，自动回将其组合进来
• Support for serving static resources, including support for WebJars (covered later in this document)).
• Automatic registration of Converter, GenericConverter, and Formatter beans.
  • Converter：转换器，比如public String test(User user);表单中传入的数字，true/false等都是文本，这些文本需要映射到User中，需要转换器，进行类型转换，将text(数字)-->int/integer，text(true)-->bool
  • Formatter ：格式化，2017/0/101--->Date
• Support for HttpMessageConverters (covered later in this document).
  • HttpMessageConverters：是SpringMVC用来http请求和响应的，比如将User--->json返回
  • HttpMessageConverters是从容器中确定的
• Automatic registration of MessageCodesResolver (covered later in this document).
• Static index.html support.
• Custom Favicon support (covered later in this document).
• Automatic use of a ConfigurableWebBindingInitializer bean (covered later in this document).

 

Spring Boot扩展 SpringMVC功能

@EnableWebMvc

　　spring mvc如果需要使用注解配置spring mvc，

@Configuration
@EnableWebMVc //需要加注解
public class MyMvcConfig implements WebMvcConfigurer{ //不需要实现WebMvcConfigurer了
    @Bean
    public WebMvcConfigurer webMvcConfigurer(){
        WebMvcConfigurer webMvcConfigurer = new WebMvcConfigurer(){
            @Override
            public void addInterceptors(InterceptorRegistry registry) {
                //拦截所有的请求，springboot帮我们已经做好了静态资源映射，所以我们可以不加excludePathPatterns("/static/**")，但是如果出现被拦截了，那就手动放行
                registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**").excludePathPatterns("/login").excludePathPatterns("/static/**");
            }
        };
        return webMvcConfigurer;
    }
}

 

在spring MVC中，我们可以编写xml来配置我们需要的一些功能，比如拦截器等等。

you can add your own @Configuration class of type WebMvcConfigurer but without @EnableWebMvc

我们可以在类型是WebMvcConfigurer的类上使用@Configuration注解，并且实现我们需要的方法；

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


@Configuration
public class MyMvcConfig implements WebMvcConfigurer{ //不需要实现WebMvcConfigurer了
    @Bean
    public WebMvcConfigurer webMvcConfigurer(){
        WebMvcConfigurer webMvcConfigurer = new WebMvcConfigurer(){
            @Override
            public void addInterceptors(InterceptorRegistry registry) {
                //拦截所有的请求，springboot帮我们已经做好了静态资源映射，所以我们可以不加excludePathPatterns("/static/**")，但是如果出现被拦截了，那就手动放行
                registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**").excludePathPatterns("/login").excludePathPatterns("/static/**");
            }
        };
        return webMvcConfigurer;
    }
}

测试的时候，直接实现方法也是可以的。所以上面的 MyMvcConfig就不需要实现 WebMvcConfigurer 方法了

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new MyInterceptor()).addPathPatterns("/xx");
    }
}

　　

 

Spring Boot全面接管SpringMVC功能

 

@Configuration
public class MyMvcConfig implements WebMvcConfigurer {

    /**
     * 注册启动页面
     * @param registry
     */
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("index");
    }

    /**
     * 配置跨域
     * @param corsRegistry
     */
    @Override
    public void addCorsMappings(CorsRegistry corsRegistry) {
        corsRegistry.addMapping("/*/**").allowedHeaders("*").allowedMethods("*").allowCredentials(true)
                .maxAge(1800).allowedOrigins("*");
    }

    /**
     * 设置json数据返回格式
     * @return
     */
    @Bean
    MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
        MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();
        ObjectMapper objectMapper = new ObjectMapper();
        //objectMapper.setPropertyNamingStrategy(new MyNameStrategy());
        objectMapper.setVisibility(objectMapper.getSerializationConfig().getDefaultVisibilityChecker()
                .withFieldVisibility(JsonAutoDetect.Visibility.ANY)
                .withGetterVisibility(JsonAutoDetect.Visibility.NONE)
                .withSetterVisibility(JsonAutoDetect.Visibility.NONE)
                .withCreatorVisibility(JsonAutoDetect.Visibility.NONE));
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
        mappingJackson2HttpMessageConverter.setObjectMapper(objectMapper);
        return mappingJackson2HttpMessageConverter;
    }

}