SpringBoot reads all properties as 0 - spring

Question

Using SpringBoot, I'm having simple class
#Component
#PropertySource("server.properties")
public class CoreFacade {
private static final Logger log = Logger.getLogger(CoreFacade.class);
#Value("${chat.server.port}")
private int port;
private Server server;
public CoreFacade() {
log.info(String.valueOf(port));
server = new Server(port);
}
}
and under src/main/resources I got server.properties with
chat.server.port = 9999
Yet logging this ends up with
INFO 2018-08-20 21:48:02,878 [main]
com.example.chatserver.core.CoreFacade [] [] - 0
instead of 9999
Any ideas what could possibly go wrong here?

Answer 1

You annotated your class as a Spring component.
It prints 0 as the constructor is invoked by Spring before any dependency injection done for the bean.
What you need is to declaring the class as a configuration class such as :
#Configuration
#PropertySource("server.properties")
public class CoreFacade {
...
}
If it makes sense you could make Server a bean defined in the class such as :
#Value("${chat.server.port}")
private int port;
#Bean
public Server server() {
return new Server(port);
}

Answer 2

An alternative solution as the one proposed by davidxxx, is to mark your constructor as #Autowired :
#Component
#PropertySource("server.properties")
public class CoreFacade {
private static final Logger log = Logger.getLogger(CoreFacade.class);
private Server server;
#Autowired
public CoreFacade(
#Value("${chat.server.port}")
int port
) {
log.info(String.valueOf(port));
server = new Server(port);
}
}
You could also use #PostConstruct, which is called after #Value resolution :
#Component
#PropertySource("server.properties")
public class CoreFacade {
private static final Logger log = Logger.getLogger(CoreFacade.class);
#Value("${chat.server.port}")
private int port;
private Server server;
#PostConstruct
public void postConstruct() {
log.info(String.valueOf(port));
server = new Server(port);
}
}