Spring Boot中@EnableAutoConfiguration和@SpringBootApplication注解的功能及联系说明

@EnableAutoConfiguration注解的功能

@EnableAutoConfiguration注解的功能:
   开启自动配置
    帮助Spring Boot应用
	  将所有符合条件@Configuration注解
	   加载到当前Spring Boot的IoC容器中

@EnableAutoConfiguration注解的源码

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.Runtime)
@Documented
@Inherited
@AutoConfigurationPackage
@Import(AutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {
 
   String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration";
 
   /**
    * Exclude specific auto-configuration classes such that they will never be applied.
    * @return the classes to exclude
    */
   Class<?>[] exclude() default {};
 
   /**
    * Exclude specific auto-configuration class names such that they will never be
    * applied.
    * @return the class names to exclude
    * @since 1.3.0
    */
   String[] excludeName() default {};
 
}

注解值说明:
  exclude:
    排除特定的自动配置类
    使其永远不会被应用 
  excludeName
    排除特定的自动配置类名
    使其永远不会被应用

@EnableAutoConfiguration注解的功能

Spring Boot
    启动加载时排除数据库加载操作
	 如下：
 
	@EnableAutoConfiguration(exclude={
			DataSourceAutoConfiguration.class,
			HibernateJpaAutoConfiguration.class
	})
	@RestController
	@SpringBootApplication
	public class HelloWorldApplication {
		//...
	}

@EnableAutoConfiguration与@SpringBootApplication的关系

@SpringBootApplication 注解包含 @EnableAutoConfiguration 注解

@SpringBootApplication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 {
    //...
}