The objects that form the backbone of your application and that are managed by the Spring IoC container are called beans. A bean is an object that is instantiated, assembled, and otherwise managed by a Spring IoC container. These beans are created with the configuration metadata that you supply to the container.
Then, what is bean annotation in spring?
Spring @Bean Annotation is applied on a method to specify that it returns a bean to be managed by Spring context. Spring Bean annotation is usually declared in Configuration classes methods. In this case, bean methods may reference other @Bean methods in the same class by calling them directly.
Secondly, how many ways can you make a bean in spring? three
Beside above, when Bean is created in spring?
By default, all beans are singletons, so whenever Application context gets created, they are all pre-loaded. If, specifically, any singleton bean has an attribute lazy-init="true" set, it will be lazy-loaded, i.e. it will be instantiated when the getBean method is called for the first time.
What is a bean method?
In computing based on the Java Platform, JavaBeans are classes that encapsulate many objects into a single object (the bean). They are serializable, have a zero-argument constructor, and allow access to properties using getter and setter methods.
What is @qualifier in spring?
The @Qualifier annotation is used to resolve the autowiring conflict, when there are multiple beans of same type. The @Qualifier annotation can be used on any class annotated with @Component or on method annotated with @Bean . This annotation can also be applied on constructor arguments or method parameters.What's the difference between @component @controller @repository & @service annotations in spring?
The difference between them is, @component is used to annotate compound classes, @Repository is a marker for automatic exception translation in the persistence layer, for service layer we need to use @service. You can refer Spring Documentation to know more.What is the difference between @component and @configuration?
@Component Indicates that an annotated class is a "component". Such classes are considered as candidates for auto-detection when using annotation-based configuration and classpath scanning. @Configuration - It is like beans. In this class, methods are annotated with @Bean which return object of the class.What is @autowired?
Autowiring happens by placing an instance of one bean into the desired field in an instance of another bean. Both classes should be beans, i.e. they should be defined to live in the application context.What is the difference between @component and @bean?
Both approaches aim to register target type in Spring container. The difference is that @Bean is applicable to methods, whereas @Component is applicable to types. @Component is a class level annotation where as @Bean is a method level annotation and name of the method serves as the bean name.What does @repository annotation do?
The @Repository annotation is a marker for any class that fulfills the role or stereotype of a repository (also known as Data Access Object or DAO). Among the uses of this marker is the automatic translation of exceptions as described in Section 20.2. 2, “Exception translation”.What is the difference between @autowired and @bean?
The @Autowired annotation is used for auto-wiring in Spring framework. The @Inject annotation also serves the same purpose, but the main difference between them is that @Inject is a standard annotation for dependency injection and @Autowired is spring specific.What is the use of @configuration in spring?
Spring @Configuration annotation is part of the spring core framework. Spring Configuration annotation indicates that the class has @Bean definition methods. So Spring container can process the class and generate Spring Beans to be used in the application.What is the Spring bean life cycle?
A “Spring bean” is just a Spring-managed instantiation of a Java class. The Spring IoC container is responsible for instantiating, initializing, and wiring beans. The container also manages the life cycle of beans. Spring provides several ways through which you can tap into the bean lifecycle.What is the purpose of @autowired in spring?
Autowiring feature of spring framework enables you to inject the object dependency implicitly. It internally uses setter or constructor injection. Autowiring can't be used to inject primitive and string values. It works with reference only.When Singleton beans are created in spring?
Singleton beans are created when the Spring container is created and are destroyed when the container is destroyed. Singleton beans are shared; only one instance of a singleton bean is created per Spring container. Singleton scope is the default scope for a Spring bean.How do you control the life cycle of a spring bean?
Spring framework provides following 4 ways for controlling life cycle events of a bean:- InitializingBean and DisposableBean callback interfaces.
- *Aware interfaces for specific behavior.
- Custom init() and destroy() methods in bean configuration file.
- @PostConstruct and @PreDestroy annotations.
