agarman · June 2, 2022 13:23
diff --git a/spring-annotations.101 b/spring-annotations.101
 Spring Annotations & Interfaces 101

 @Configuration
 - a singleton bean that is used to configure an application
 - can be used as a component/bean itself
 - can have 0 or more methods that register additional beans
 - constructor can take parameters as long as these parameters can be resolved to already registered beans

 @Component
 - a singleton bean that provides functionality to application
 - constructor can take parameters as long as these parameters can be resolved to already registered beans

 @Value
 - annotation specifying how to set a field using properties or a property loader
 - at Manhattan, properties are loaded in this order: component.properties, kv-store, environmental variables
 - should use sparringly, preferrably only in @Configuration classes

 @Autowired
 - annotation specifying that a field should be set from using a registered bean that matches the fields type & name

 @Lazy
 - annotation specifying to only construct & load a bean when it's referenced

 @Bean
 - annotation attached to a method to register it's return as a bean
 - method can take parameters as long as these parameters can be resolved to already registered beans

 @Primary
 - annotation attached to a bean to control which instance of a bean to use; resolves an otherwise ambiguous search

 ApplicationContextAware
 - interface that allows configuration of component after fields are set but before component is registered
 - allows loading beans programmatically from ApplicationContext

 InitializingBean
 - interface that allows configuration of component after fields are set but before component is registered
 - prefer InitilizingBean to ApplicationContextAware


 Spring Component Lifecycle
 1. Construct
 2. Set @Value fields
 3. Set @Autowired fields
 4. Invoke @PostConstruct methods
 5. Invoke setApplicationContext from ApplicationContextAware
 6. Invoke afterPropertiesSet from InitializingBean
 7. Invoke @Bean methods
	Spring Annotations & Interfaces 101

	@Configuration
	- a singleton bean that is used to configure an application
	- can be used as a component/bean itself
	- can have 0 or more methods that register additional beans
	- constructor can take parameters as long as these parameters can be resolved to already registered beans

	@Component
	- a singleton bean that provides functionality to application
	- constructor can take parameters as long as these parameters can be resolved to already registered beans

	@Value
	- annotation specifying how to set a field using properties or a property loader
	- at Manhattan, properties are loaded in this order: component.properties, kv-store, environmental variables
	- should use sparringly, preferrably only in @Configuration classes

	@Autowired
	- annotation specifying that a field should be set from using a registered bean that matches the fields type & name

	@Lazy
	- annotation specifying to only construct & load a bean when it's referenced

	@Bean
	- annotation attached to a method to register it's return as a bean
	- method can take parameters as long as these parameters can be resolved to already registered beans

	@Primary
	- annotation attached to a bean to control which instance of a bean to use; resolves an otherwise ambiguous search

	ApplicationContextAware
	- interface that allows configuration of component after fields are set but before component is registered
	- allows loading beans programmatically from ApplicationContext

	InitializingBean
	- interface that allows configuration of component after fields are set but before component is registered
	- prefer InitilizingBean to ApplicationContextAware


	Spring Component Lifecycle
	1. Construct
	2. Set @Value fields
	3. Set @Autowired fields
	4. Invoke @PostConstruct methods
	5. Invoke setApplicationContext from ApplicationContextAware
	6. Invoke afterPropertiesSet from InitializingBean
	7. Invoke @Bean methods