@ComponentScan vs @EntityScan

Posted on by Admin

@ComponentScan is used for scanning all your components those are marked as @Controller, @Service, @Repository, @Component etc… where @EntityScan is used to scan all your Entities those are marked @Entity for any configured JPA in your application.

 

@ComponentScan:

@Retention(value=RUNTIME)
@Target(value=TYPE)
@Documented
@Repeatable(value=ComponentScans.class)
public @interface ComponentScan

Configures component scanning directives for use with @Configuration classes. It is as same as writing Spring XML’s <context:component-scan> element. The  value()  attribute may be specified to define specific packages to scan. If specific packages are not defined, scanning will occur from the package of the class that declares this annotation.

i.e.

@ComponentScan("org.example.base")
public class MyConfig {
   ...
}

Point to be noted here is that then you use XML’s  <context:component-scan>  it comes with an attribute annotation-config. Which is boolean flag “Indicates whether the implicit annotation post-processors should be enabled. Default is ‘true’.” In simple words, if it is true then you can create objects of you classes and resolve dependencies by annotating them with @Controller, @Service, @Repository etc and if you set it as false then you will have to declare all your Spring Beans into XMLs.

But when using @ComponentScan, in almost all cases default annotation config processing (e.g. processing @Autowired and friends) is assumed. Furthermore, when using AnnotationConfigApplicationContext, annotation config processors are always registered, meaning that any attempt to disable them at the @ComponentScan level would be ignored.

@EntityScan

It configures the base packages used by auto-configuration when scanning for entity classes.

Using @EntityScan will cause auto-configuration to:

  • Set the packages scanned for JPA entities.
  • Set the packages used with SessionFactory.
  • Set the initial entity set used with Spring Data  MongoDB, Cassandra  and   Couchbase mapping contexts.

 

Hope this clear your doubts!!