启动器

@SpringBootApplication
public class ApplicationRun {
    
       public static void main(String[] args) {
            SpringApplication.run(ApplicationRun.class , args);
        }
}

配置类

@Configuration
@EnableWebMvc
public class MyMvcConfig extends WebMvcConfigurerAdapter {

    @Bean
    public ViewResolver getViewResolver() {
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/views/");
        resolver.setSuffix(".jsp");
        return resolver;
    }
    @Override
    public void configureDefaultServletHandling(
            DefaultServletHandlerConfigurer configurer) {
        configurer.enable();
    }
}

===========

application.yml

注意~ 在 ： 后面一定要加上空格！
spring:
 mvc:
  view:
   prefix : /WEB-INF/views/
   suffix : .jsp
sever:
    port: 9999

前端控制器

@Controller
public class SseController {
    
    @RequestMapping(value="/push") //①
    public String get() {
        return "see";
    }
}