背景
包装一个用户服务,一部分功能需要调用远程服务,而另一部分功能调用本地方法,如:
@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");
}
}
为了简化篇幅,并没有处理异常。
当使用者使用这两个用户相关的服务,就需要自动装载两个Service:
@Autowired
private LocalUserService localUserService;
@Autowired
private RemoteUserService remoteUserService;
能不能简化一下呢?将两个服务整合。
尝试将本地方法加入Feign接口
@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:
测试发现,UserService 接口中定义本地方法 getUserId() 编译器直接报错了,要求必须有Mapping注解。
尝试通过实现两个接口
换一个思路,回到最初,在熔断器中实现两个接口:
@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:
测试发现,本地方法正常,远程方法根本无效,好像就是一个本地方法,直接走到了熔断方法中。
IS -> HAS
让 RemoteUserService is LocalUserService 既然不行,那么就试试让 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");
}
}
这样是可以的。编码时稍微麻烦了一点,使用时就清晰多了。