Springbootの高度な応用

@ConditionalOnBean and @ConditionalOnMissingBean
beanが存在する場合に実行

@Configuration
public class MyAutoConfiguration {

	@Bean
	@ConditionalOnMissingBean
	public MyService myService() { ... }

}

@ConditionalOnClass and @ConditionalOnMissingClass
@ConditionalOnProperty
@ConditionalOnResource
@ConditionalOnResource and @ConditionalOnNotWebApplication
@ConditionalOnExpression