springboot拓展MVC

SpringBoot官网摘取

原文
If you want to keep those Spring Boot MVC customizations and make more MVC customizations (interceptors, formatters, view controllers, and other features), you can add your own @Configuration class of type WebMvcConfigurer but without @EnableWebMvc.

If you want to provide custom instances of RequestMappingHandlerMapping, RequestMappingHandlerAdapter, or ExceptionHandlerExceptionResolver, and still keep the Spring Boot MVC customizations, you can declare a bean of type WebMvcRegistrations and use it to provide custom instances of those components.

If you want to take complete control of Spring MVC, you can add your own @Configuration annotated with @EnableWebMvc, or alternatively add your own @Configuration-annotated DelegatingWebMvcConfiguration as described in the Javadoc of @EnableWebMvc.

示例

// 如果你想diy一些定制化的功能,只要写这个组件,然后将它交给SpringBoot,
// SpringBoot就会帮我们自动装配!
// 扩展 SpringMVC
@Configuration
//@EnableWebMvc//这玩意就是导入了一个类: DelegatingWebMvcConfiguration: 从容器中获取所有的webmvc config
public class MyMvcConfig implements WebMvcConfigurer {

    // ViewResolver 实现了视图解析器接口的类,我们就可以把它看作视图解析器
    @Bean
    public ViewResolver myViewResolver() {
        return new MyViewResolver();
    }

    //  自定义了一个自己的视图解析器MyViewResolver
    public static class MyViewResolver implements ViewResolver {
        @Override
        public View resolveViewName(String s, Locale locale) throws Exception {
            return null;
        }
    }
}

@EnableWebMvc源码分析

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Import(DelegatingWebMvcConfiguration.class)
public @interface EnableWebMvc {
}

@Configuration(proxyBeanMethods = false)
public class DelegatingWebMvcConfiguration extends WebMvcConfigurationSupport {
}

@Configuration
@ConditionalOnWebApplication(
    type = Type.SERVLET
)
@ConditionalOnClass({Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class})
@ConditionalOnMissingBean({WebMvcConfigurationSupport.class})
@AutoConfigureOrder(-2147483638)
@AutoConfigureAfter({DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class, ValidationAutoConfiguration.class})
public class WebMvcAutoConfiguration {
}