@Target(value={TYPE,METHOD}) @Retention(value=RUNTIME) @Inherited @Documented public @interface Primary
This annotation is semantically equivalent to the <bean> element's
primary attribute in Spring XML.
May be used on any class directly or indirectly annotated with
@Component or on methods annotated with @Bean.
@Component
public class FooService {
private FooRepository fooRepository;
@Autowired
public FooService(FooRepository fooRepository) {
this.fooRepository = fooRepository;
}
}
@Component
public class JdbcFooRepository {
public JdbcFooService(DataSource dataSource) {
// ...
}
}
@Primary
@Component
public class HibernateFooRepository {
public HibernateFooService(SessionFactory sessionFactory) {
// ...
}
}
Because HibernateFooRepository is marked with @Primary,
it will be injected preferentially over the jdbc-based variant assuming both
are present as beans within the same Spring application context, which is
often the case when component-scanning is applied liberally.
Note that using @Primary at the class level has no effect unless
component-scanning is being used. If a @Primary-annotated class is
declared via XML, @Primary annotation metadata is ignored, and
<bean primary="true|false"/> is respected instead.
Lazy,
Bean,
ComponentScan,
Component