Not able to access Spring boot application.properties

Question

I am trying to access application.properties values in spring boot application's service class. But every time value is null, so it throws NullPointException. I can get the right value for port in controller class(if i add @Autowired in controller) but not in service class. What changes are required to make this properties available through out the application?

Controller looks like:

@RestController
public class MyController {

MyService ss = new MyService();


 @RequestMapping(value = "/myapp/abcd", method = RequestMethod.POST, consumes = {"application/json"})
    public ResponseMessage sendPostMethod(@RequestBody String request) {
        log.debug(" POST Request received successfully; And request body is:"+ request);

        ResponseMessage response = ss.processRequest(request);
        return response;

    }

}

And Service class is:

@Service
public class MyService {

    private ApplicationProperties p;

    @Autowired 
    public setProps(ApplicationProperties config) {
           this.p = config;
    }

    public ResponseMessage processRequest(String request) {
          System.out.println("Property value is:"+ p.getPort());
    }

}

ApplicationProperties.java looks like:

@Component
@Getter
@Setter
@ConfigurationProperties
public class ApplicationProperties {

     String port;
}

Finally, application.properties file has:

port=1234

I have even tried passing ApplicationProperties instance from controller to service's default constructor, but it did not work. When I debug, value persist while application startup, but when I make a rest web service POST call, it is null.

Answer 1

In your controller MyController, you have to inject the service, replacing:

MyService ss = new MyService();

by:

@Autowired
MyService ss;

Also, instead of your ApplicationProperties class, you can use @Value annotation, from Spring, to load properties from application.properties file. Take a look at this code:

import org.springframework.beans.factory.annotation.Value;
// ...

@Service
public class MyService {

    @Value("${port}")
    private String port;

    // ...
}