spring boot 启动原理

任何一个Spring boot 项目都包含以下代码：

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

@SpringbootApplication 是一个核心注解，同时也是组合注解[即包含@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan]：

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = {
        @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
        @Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {}

所以：@SpringBootApplicatoin注解=@Configuration