1 springboot 默认扫描自己根目录下及子目录里面的controller
2 自动配置 WebMvcAutoConfiguration因为条件没满足而没有执行自动配置,例如缺少spring-webmvc包
@ConditionalOnWebApplication @ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurerAdapter.class }) @ConditionalOnMissingBean(WebMvcConfigurationSupport.class)