@ComponentScan is used to determine which Spring Beans are available in the application context. The packages to scan can be
configured thanks to the basePackageClasses or basePackages (or its alias value) parameters. If neither
parameter is configured, @ComponentScan will consider only the package of the class annotated with it. When @ComponentScan
is used on a class belonging to the default package, the entire classpath will be scanned.
This will slow-down the start-up of the application and it is likely the application will fail to start with an
BeanDefinitionStoreException because you ended up scanning the Spring Framework package itself.
This rule raises an issue when:
-
@ComponentScan, @SpringBootApplication and @ServletComponentScan are used on a class belonging to the
default package
-
@ComponentScan is explicitly configured with the default package
Noncompliant code example
import org.springframework.boot.SpringApplication;
@SpringBootApplication // Noncompliant; RootBootApp is declared in the default package
public class RootBootApp {
...
}
@ComponentScan("")
public class Application {
...
}
Compliant solution
package hello;
import org.springframework.boot.SpringApplication;
@SpringBootApplication // Compliant; RootBootApp belongs to the "hello" package
public class RootBootApp {
...
}
