父类获取子类私有属性 Field getDeclaredFields setAccessible

service

public interface BaseService {
   void work();
}

public interface ChildService extends BaseService{
}

public class ChildServiceImpl implements ChildService {
    @Override
    public void work() {
        System.out.println("work");
    }
}

controller

public class BaseController {

    public  void work(){
        getService().work();
    }

    private BaseService getService() {
        try{
            Field[] fileds = this.getClass().getDeclaredFields();
            for(Field field:fileds){
                if(BaseService.class.isAssignableFrom(field.getType())){
                    field.setAccessible(true);
                    return (BaseService)field.get(this);
                }
            }
            return null;
        }catch (Exception e){
            e.printStackTrace();
            return null;
        }

    }

}

public class ChildController extends BaseController{

    private ChildService childService = new ChildServiceImpl();

    public static void main(String[] args) {
        ChildController controller = new ChildController();
        controller.work();
    }
}