SpringBootApplication注解的简介说明

我们都知道SpringBoot程序启动入口是SpringApplication.run
在其上面会加上一个@SpringBootApplication注解
此注解是由三部分组成

 @ComponentScan注解：
    用于组件扫描和自动装配
 @SpringBootConfiguration注解：
    继承@Configuration注解，主要用于加载配置文件
 @EnableAutoConfiguration注解:这个注释启用了Spring Boot的自动配置功能
   可以自动为您配置很多东西

SpringBootApplication注解源码

@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 {
    @AliasFor(annotation = EnableAutoConfiguration.class)
    Class[] exclude() default {};

    @AliasFor(annotation = EnableAutoConfiguration.class)
    String[] excludeName() default {};

    @AliasFor(annotation = ComponentScan.class, attribute = "basePackages")
    String[] scanBasePackages() default {};
	@AliasFor(annotation = ComponentScan.class, attribute = "basePackageClasses")
    Class[] scanBasePackageClasses() default {};
}

例:
SpringBoot示例

@SpringBootApplication
public class TestSpringBoot implements commandlinerunner {
 
    private static final Logger log = LoggerFactory.getLogger(TestSpringBoot.class);
 
    public static void main(String args[]) {
        SpringApplication.run(TestSpringBoot.class);
    }
 
    @Override
    public void run(String...args) throws Exception {
        log.info("welcome java265.com!");
    }
}