@Component is a class-level annotation. It is used to denote a class as a Component. We can use @Component across the application to mark the beans as Spring’s managed components. A component is responsible for some operations.

What is @service and @component in Spring?

@Component is a generic stereotype for any Spring-managed component. @Service annotates classes at the service layer. @Repository annotates classes at the persistence layer, which will act as a database repository.

What is difference between @component and @bean?

It is used to explicitly declare a single bean, rather than letting Spring do it automatically. If any class is annotated with @Component it will be automatically detect by using classpath scan. We should use @bean, if you want specific implementation based on dynamic condition.

What is @component annotation in Spring?

@Component is an annotation that allows Spring to automatically detect our custom beans. In other words, without having to write any explicit code, Spring will: Scan our application for classes annotated with @Component. Instantiate them and inject any specified dependencies into them. Inject them wherever needed.

What is the scope of @component in Spring?

The singleton scope is the default scope in Spring. singleton (Default) Scopes a single bean definition to a single object instance per Spring IoC container.

Is @component a singleton?

Yes, that is correct, @Component is a Spring bean and a Singleton. About singletons – spring beans are all in singleton scope by default.

Can we use @component instead of controller?

@Component serves as a generic stereotype for any Spring-managed component; whereas, @Repository, @Service, and @Controller serve as specializations of @Component for more specific use cases (e.g., in the persistence, service, and presentation layers, respectively).

What is difference between @component and @ComponentScan?

The main difference between these annotations is that @ComponentScan scans for Spring components while @EnableAutoConfiguration is used for auto-configuring beans present in the classpath in Spring Boot applications. Now, let’s go through them in more detail.

Can we use @component instead of @repository?

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.

Can we use @component and @service in same class?

tl;dr: Use @Component or @Service on both, and there’s no significant difference between them ( @Component is becoming more usual because of that).

Is @repository a bean?

@ComponentScan ensures that the classes decorated with @Component and their derivatives including @Repository are found and registered as Spring beans.

What is the difference between @autowired and bean?

@Bean is just for the metadata definition to create the bean(equivalent to tag). @Autowired is to inject the dependancy into a bean(equivalent to ref XML tag/attribute).

What is the difference between Autowired and inject?

@Inject and @Autowired both annotations are used for autowiring in your application. @Inject annotation is part of Java CDI which was introduced in Java 6, whereas @Autowire annotation is part of spring framework. Both annotations fulfill same purpose therefore, anything of these we can use in our application.

What is @component scan in Spring boot?

Using component scan is one method of asking Spring to detect Spring managed components. Spring needs the information to locate and register all the Spring components with the application context when the application starts. Spring can auto scan, detect, and instantiate components from pre-defined project packages.

What is the difference between @component @repository @service and @controller?

@Component is a generic stereotype for any Spring-managed component or bean. @Repository is a stereotype for the persistence layer. @Service is a stereotype for the service layer. @Controller is a stereotype for the presentation layer (spring-MVC).

What is @configuration in Spring?

One of the most important annotations in spring is @Configuration annotation which 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. This annotation is part of the spring core framework.