retrofit
public interface MyApiEndpointInterface {
// Request method and URL specified in the annotation
@GET("users/{username}")
Call<User> getUser(@Path("username") String username);
@GET("group/{id}/users")
Call<List<User>> groupList(@Path("id") int groupId, @Query("sort") String sort);
@POST("users/new")
Call<User> createUser(@Body User user);
}