无法在Spring Boot中连接到Postgresql数据库

<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
</dependency>

spring.datasource.url=jdbc:postgresql://localhost:5432/db_name
spring.datasource.username=db_username
spring.datasource.password=db_password
spring.datasource.driver-class-name=org.postgresql.Driver

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    // 添加自定义的数据库操作方法
}

@Service
public class UserService {
    private final UserRepository userRepository;

    public UserService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    public User getUserById(Long id) {
        return userRepository.findById(id).orElse(null);
    }

    public User saveUser(User user) {
        return userRepository.save(user);
    }

    // 其他数据库操作方法
}