@EnableWebMvc,WebMvcConfiguratio

1.WebMvcConfigurationAdapter已经废弃，最好用implements WebMvcConfigurer代替:

@Configuration
public class DefaultWebMvcConfig implements WebMvcConfigurer {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("swagger-ui.html").addResourceLocations("classpath:/META-INF/resources/");
        registry.addResourceHandler("/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/");
    }
}

2.如果使用继承WebMvcConfigurationSupport(使用@EnableWebMvc注解或继承DelegatingWebMvcConfiguration同理)，会覆盖application.properties中关于WebMvcAutoConfiguration的设置，需要在自定义配置中实现:

@Configuration
public class DefaultWebMvcConfig extends WebMvcConfigurationSupport {

}
@Configuration
@EnableWebMvc
public class DefaultWebMvcConfig implements WebMvcConfigurer {

}
@Configuration
public class DefaultWebMvcConfig extends DelegatingWebMvcConfiguration {

}

上面代码中需要在类中实现关于WebMvcAutoConfiguration的配置，而不是在application.properties中:

@Configuration
public class DefaultWebMvcConfig extends WebMvcConfigurationSupport {
   
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter = new MappingJackson2HttpMessageConverter();
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        objectMapper.configure(MapperFeature.ACCEPT_CASE_INSENSITIVE_ENUMS, true);
        objectMapper.setTimeZone(TimeZone.getTimeZone("GMT+8"));
        objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
        mappingJackson2HttpMessageConverter.setObjectMapper(objectMapper);
        converters.add(mappingJackson2HttpMessageConverter);
        super.addDefaultHttpMessageConverters(converters);
    }
}

总结

implements WebMvcConfigurer ： 不会覆盖@EnableAutoConfiguration关于WebMvcAutoConfiguration的配置
@EnableWebMvc + implements WebMvcConfigurer ： 会覆盖@EnableAutoConfiguration关于WebMvcAutoConfiguration的配置
extends WebMvcConfigurationSupport ：会覆盖@EnableAutoConfiguration关于WebMvcAutoConfiguration的配置
extends DelegatingWebMvcConfiguration ：会覆盖@EnableAutoConfiguration关于WebMvcAutoConfiguration的配置

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