Spring - proper way to use @Component annotated class in Main

Question

I have my TCPServer class implementing Runnable and annotated with @Component. And I have a ThreadPoolTaskExecutor which will run the TCPServer.

In TCPServer I also have a class which is annotated with @Repository. If I try to call taskExecutor.execute(new TCPServer()) this will not be managed by Spring so my repository object will be null.

How can I get an instance of TCPServer in Main so I can give it to taskExecutor?

TCPServer:

@Component
@Scope("prototype")
public class TCPServer implements Runnable {

  @Autowired
  private StudentRepository studentRepository;
  //rest of code
}

StudentRepository:

@Repository
public interface StudentRepository extends CrudRepository<Student, Long> {

}

I already tried like this:

TCPServer tcpServer = (TCPServer) applicationContext.getBean("tcpServer");

But this is what I got:

Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'tcpServer' available

Edit:

MySpringApplication: com.example.myspringapp;

TCPServer: com.example.myspringapp.server;

Answer 1

If the class is called TCPServer, the bean name will be TCPServer (apparently Spring doesn't lowercase the first character, if the class name starts with a sequence of uppercase characters). For the bean name tcpServer, the class name has to be TcpServer.

Alternatively, you can specify the bean name in the Component annotation:

@Component("tcpServer")

For getting the bean by type, you have to use the correct type. If your class implements an interface and you didn't specify

@EnableAspectJAutoProxy(proxyTargetClass = true)

on your main configuration class, Spring will use default JDK proxies to create the beans, which implement then the interfaces of the class and don't extend the class itself. So the bean type of TCPServer in your case is Runnable.class and not TCPServer.class.

So either use bean names to get the bean or add the proxy annotation to use the class as type.