发出获取在CrudRepository中生成的命令以将其转换为函数

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;

@Repository
public interface UserRepository extends CrudRepository<User, Long> {
    // 在这里定义自定义的查询方法
}

@Repository
public interface UserRepository extends CrudRepository<User, Long> {
    @Query("SELECT u FROM User u WHERE u.username = :username")
    User findByUsername(@Param("username") String username);
}

@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;

    public User getUserByUsername(String username) {
        return userRepository.findByUsername(username);
    }
}