Question: What Is @ComponentScan In Spring Boot?

What is the use of @ComponentScan in spring boot?

The @ComponentScan annotation is used with the @Configuration annotation to tell Spring the packages to scan for annotated components.

@ComponentScan also used to specify base packages and base package classes using thebasePackageClasses or basePackages attributes of @ComponentScan..

What is @ComponentScan in spring?

Simply put – @ComponentScan tells Spring in which packages you have annotated classes which should be managed by Spring. So, for example, if you have a class annotated with @Controller which is in a package which is not scanned by Spring, you will not be able to use it as Spring controller.

What is the difference between @component and @ComponentScan?

Using the annotation @ComponentScan , you can tell Spring where do your Spring-managed components lie. … On the other hand, @Component is a generic annotation for any Spring-Managed component. For example – If you create a class called Testing inside the package com. example.

What is @requestbody?

This is used to convert the body of the HTTP request to the java class object with the aid of selected HTTP message converter. This annotation will be used in the method parameter and the body of the http request will be mapped to that method parameter.

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 @RequestMapping?

@RequestMapping is one of the most common annotation used in Spring Web applications. This annotation maps HTTP requests to handler methods of MVC and REST controllers. In this post, you’ll see how versatile the @RequestMapping annotation is when used to map Spring MVC controller methods.

Can we use @service instead of @repository?

According to documentaion @Repository , @Service , @Controller are all synonyms. They all just specializations of @Component annotation. So, generally, they can be used one istead of other. … First reason: any of this annotations make clear the role of your component in the application.

What is a bean in spring?

In Spring, 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. Otherwise, a bean is simply one of many objects in your application.

What is @EnableAutoConfiguration in spring?

Annotation Type EnableAutoConfiguration Enable auto-configuration of the Spring Application Context, attempting to guess and configure beans that you are likely to need. Auto-configuration classes are usually applied based on your classpath and what beans you have defined. For example, if you have tomcat-embedded.

What is @SpringBootApplication in spring boot?

Spring Boot @SpringBootApplication annotation is used to mark a configuration class that declares one or more @Bean methods and also triggers auto-configuration and component scanning. It’s same as declaring a class with @Configuration, @EnableAutoConfiguration and @ComponentScan annotations.

How do I scan for spring boot?

Using @ComponentScan in a Spring Application. With Spring, we use the @ComponentScan annotation along with @Configuration annotation to specify the packages that we want to be scanned. @ComponentScan without arguments tells Spring to scan the current package and all of its sub-packages.

What is the difference between @bean and @component?

@Component auto detects and configures the beans using classpath scanning whereas @Bean explicitly declares a single bean, rather than letting Spring do it automatically.

What is the difference between @RequestParam and @PathVariable?

1) The @RequestParam is used to extract query parameters while @PathVariable is used to extract data right from the URI. … Even though both are used to extract data from URL, @RequestParam is used to retrieve query parameters, anything after ? in the URL, while @PathVariable is used to retrieve values from URI itself.

What is value in @RequestMapping?

As mentioned in the comments (and the documentation), value is an alias to path . Spring often declares the value element as an alias to a commonly used element. … This is an alias for path() . For example @RequestMapping(“/foo”) is equivalent to @RequestMapping(path=”/foo”) .

What is @bean annotation in spring?

Annotating a class with the @Configuration indicates that the class can be used by the Spring IoC container as a source of bean definitions. The @Bean annotation tells Spring that a method annotated with @Bean will return an object that should be registered as a bean in the Spring application context.

Why @component is used in spring?

Spring Component annotation is used to denote a class as Component. It means that Spring framework will autodetect these classes for dependency injection when annotation-based configuration and classpath scanning is used.

Is @component a singleton?

2 Answers. Yes, that is correct, @Component is a Spring bean and a Singleton. About singletons – spring beans are all in singleton scope by default. The only thing you have to have in mind is that you should not store state in field variables (they should only hold dependencies).

What is the difference between @bean and @autowired?

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 does @repository mean in spring?

@Repository is a Spring annotation that indicates that the decorated class is a repository. A repository is a mechanism for encapsulating storage, retrieval, and search behavior which emulates a collection of objects.

What is 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 @bean used for?

@Bean is used to mark a method as one that creates a bean and Spring will then add it to the context for us. The return type of the method defines the type of bean that is created, so both of the beans created in this example will be referred to by the type MyBean rather than their implementations.