springboot使用war包部署到外部tomcat过程解析

@SpringBootApplication
//继承SpringBootServletInitializer子类
public class Demo2Application extends SpringBootServletInitializer {

  //重写configure方法
  @Override
  protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
    return application.sources(Demo2Application.class);
  }
  public static void main(String[] args) {
    SpringApplication.run(Demo2Application.class, args);
  }
}