Spring Component Scan Process
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The document discusses @Component, @Configuration, and @Bean annotations in Spring. @Component scans packages to automatically detect classes to register as beans. @Configuration allows declaring and configuring beans directly within classes. @Bean defines methods that create and return beans. The component scan process involves parsing the configuration, scanning classes based on include/exclude filters, registering bean definitions, and finishing bean initialization. Debugging shows how classes are parsed and beans registered. Dependency injection types are compared, with constructor injection being most reliable and testable due to immutability and dependency detection. Circular dependencies can cause stack overflows at runtime.
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Spring Component Scan Process
- 1. Week5. & Section 6. (Section 7. ) 11 1 Covenant Ko 2021. 06. 23(Wed)
- 2. @Component vs @Configuration @Bean ???
- 3. @Component vs @Configuration @Bean Component Bean - 1 @Bean @Configuration - Bean - 개발자가 직접 제어가 불가능한 외부 라이브러리등을 Bean으로 만들려 할때 사용 - Bean으로 등록된 Method는 개발자가 직접 제어가 불가능하다는 것 - Bean ( ) - @Controller, @Service, @Repository - Bean - @Component 어노테이션은 @Autowired 어노테이션을 이용하여 사용한다. @Autowired를 사용해 의존성을 주입 https://velog.io/@albaneo0724/Spring-Component -Configuration -
- 4. Bean ? User class @Bean User class Bean Bean
- 6. Bean Life Cycle We are here!
- 8. Component Scan Process 1. Configuration 2. ComponentScan 3. Class 4. 5. &
- 9. Component Scan Process 1. Configuration 2. ComponentScan 3. Class 4. 5. & - ConfigurationClassParser Configuration
- 10. Component Scan Process 1. Configuration 2. ComponentScan 3. Class 4. 5. & - ComponentScanAnnotationParser가 컴포넌트 후보를 모두 찾고, 스캔하기 위하여 해당 설정을 파싱하여 가져옴 - basePackages, basePackesClasses, excludeFilters, includeFilters, lazyInit, nameGenerator, resourcePattern, scopedProxy 등 컴포넌 트들을 스캔하기 위한 설정
- 11. Component Scan Process 1. Configuration 2. ComponentScan 3. Class 4. 5. & - basePackage - ( *.class ) Resource
- 12. Component Scan Process 1. Configuration 2. ComponentScan 3. Class 4. 5. & - ( ) BeanDefinition - beanName key BeanDefinitionRegistry . ( )
- 13. Component Scan Process 1. Configuration 2. ComponentScan 3. Class 4. 5. & - AbstractApplicationContext finishBeanFactoryInitialization(beanFactory); - ,
- 14. Component Scan Process 1. Configuration 2. ComponentScan 3. Class 4. 5. & DEBUGGING TIME
- 25. Debugging
- 29. Constructor Injection Reliability Field Injection Setter Injection More reliable because of immutable variables Less reliable https://medium.com/engineering-zemoso/when-not-to-autowire-in-spring-spring-boot-93e6a01cb793 Less reliable 의존성 주입이 필요한 필드를 final 로 선언가능
- 30. https://medium.com/engineering-zemoso/when-not-to-autowire-in-spring-spring-boot-93e6a01cb793 Maintainability Constructor Injection Field Injection Setter Injection Constructor injection helps in identifying the list of dependencies and can easily be used to make the code more readable Since Autowired fields can easily mix up with regular fields, it gets difficult to track the dependencies of the class Same as Field Injection
- 31. https://medium.com/engineering-zemoso/when-not-to-autowire-in-spring-spring-boot-93e6a01cb793 Cyclic Dependency detection Constructor Injection Field Injection Setter Injection Cyclic dependencies can easily be detected and fixed using Constructor Injection. Field Injection does not detect cyclic dependencies. Setter Injection does not detect cyclic dependencies.
- 32. https://medium.com/engineering-zemoso/when-not-to-autowire-in-spring-spring-boot-93e6a01cb793 Testability Constructor Injection Field Injection Setter Injection Mocking the dependencies become easier as they can be mocked and passed using constructor even without creating Spring Context which enables faster and cleaner tests Mocking becomes challenging as creating mock beans and actual beans and shuffling between them becomes tedious Mocking is easy as mock object can directly be set
- 34. Circular Reference > > > > ( ...) https://velog.io/@walker/Spring-%EC%99%9C-%EC%83%9D%EC%84%B1%EC%9E%90-%EC%A3%BC%EC%9E%85%EC%9D%B4-%EA%B6%8C%EC%9E%A5%EB%90%98%EB%A9%B0-%EC%88%9C%ED%99%98%EC%B0%B8%EC%A1%B0%EB%9E%80-%EB%AD%98%EA%B9%8C
- 35. Circular Reference > > > > ( ...) https://velog.io/@walker/Spring-%EC%99%9C-%EC%83%9D%EC%84%B1%EC%9E%90-%EC%A3%BC%EC%9E%85%EC%9D%B4-%EA%B6%8C%EC%9E%A5%EB%90%98%EB%A9%B0-%EC%88%9C%ED%99%98%EC%B0%B8%EC%A1%B0%EB%9E%80-%EB%AD%98%EA%B9%8C StackOverflow = Runtime Error
- 36. - Keesun Baik - https://www.slideshare.net/whiteship/ss-5766801 - https://docs.spring.io/spring-framework/docs/3.0.0.M4/reference/html/ch03s10.html - component-scan - https://velog.io/@hyun-jii/%EC%8A%A4%ED%94%84%EB%A7%81-component-scan- %EA%B0%9C%EB%85%90-%EB%B0%8F-%EB%8F%99%EC%9E%91-%EA%B3%BC%EC%A0%95 - ComponentScan - https://jess-m.tistory.com/14 - https://velog.io/@hyun-jii/%EC%8A%A4%ED%94%84%EB%A7%81-component-scan- %EA%B0%9C%EB%85%90-%EB%B0%8F-%EB%8F%99%EC%9E%91-%EA%B3%BC%EC%A0%95 - ComponentScan Debugging - https://www.inflearn.com/questions/155121 - ComponentScan - https://jess-m.tistory.com/14 - Classpath scanning and managed components (Spring doc) - https://docs.spring.io/spring-framework/docs/3.0.0.M4/reference/html/ch03s10.html - <context:component-scan> ‒ NHN Entertainment - https://thswave.github.io/spring/2015/02/02/spring-mvc-annotaion.html - - https://xlffm3.github.io/spring%20&%20spring%20boot/Chapter4_Component_Scan/ ( ) - https://reflectoring.io/spring-component-scanning/ - - https://medium.com/engineering-zemoso/when-not-to-autowire-in-spring-spring-boot-93e6a01cb793
- 37. & Week5. & END.