background

To wrap a user service, some functions need to call remote services, while others need to call local methods, such as:

@FeignClient(value="USER-SERVICE")
public interface RemoteUserService{
  @GetMapping("getUserByUserId")
  public User getUserByUserId(String userId);
}

public interface LocalUserService{
  public String getUserId();
}

@Service
public class LocalUserServiceImpl implements LocalUserService{
  @Autowired
  private HttpServletRequest request;
  public String getUserId(){
    return (String)request.getSession().getAttribute("user-id");
  }
}

To simplify the length, no exceptions were handled.

When users use these two user related services, they need to automatically load two services:

@Autowired
private LocalUserService localUserService;

@Autowired
private RemoteUserService remoteUserService;

Can you simplify it? Integrate the two services.

Try to add the local method to the Feign interface

@FeignClient(value="USER-SERVICE",fallback=UserServiceHystrix.class)
public interface UserService{
  @GetMapping("getUserByUserId")
  public User getUserByUserId(String userId);

  public String getUserId();
}

@Service
public class UserServiceHystrix implements UserService{
  @Autowired
  private HttpServletRequest request;

  public User getUserByUserId(String userId){
    return null;
  }

  public String getUserId(){
    return (String)request.getSession().getAttribute("user-id");
  }
}

Fail:

The test found that the local method getUserId() compiler defined in the UserService interface directly reported an error, requiring a Mapping annotation.

Try to implement two interfaces

In another way, back to the beginning, two interfaces are implemented in the fuse:

@FeignClient(value="USER-SERVICE",fallback=UserServiceHystrix.class)
public interface UserService{
  @GetMapping("getUserByUserId")
  public User getUserByUserId(String userId);
}

public interface LocalUserService extends RemoteUserService{
  public String getUserId();
}

@Service
public class UserServiceHystrix implements LocalUserService,RemoteUserService{
  @Autowired
  private HttpServletRequest request;

  public User getUserByUserId(String userId){
    return null;
  }

  public String getUserId(){
    return (String)request.getSession().getAttribute("user-id");
  }
}

Fail:

The test shows that the local method is normal, and the remote method is not effective at all. It seems that it is just a local method that goes directly to the fusing method.

IS -> HAS

Since RemoteUserService is LocalUserService is not available, try LocalUserService has RemoteUserService.

@FeignClient(value="USER-SERVICE",fallback=UserServiceHystrix.class)
public interface UserService{
  @GetMapping("getUserByUserId")
  public User getUserByUserId(String userId);
}

public interface LocalUserService extends RemoteUserService{
  public String getUserId();
}

@Service
public class UserServiceImpl implements LocalUserService,RemoteUserService{
  @Autowired
  private HttpServletRequest request;
  @Autowire
  private RemoteUserService remoteUserService;

  public User getUserByUserId(String userId){
    return remoteUserService.getUserByUserId(userId);
  }

  public String getUserId(){
    return (String)request.getSession().getAttribute("user-id");
  }
}

This is OK. It's a little bit troublesome when coding, and it's much clearer when using.