如何使用Spring Boot动态连接到postgresql数据库

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

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

spring.datasource.url=jdbc:postgresql://localhost:5432/mydatabase
spring.datasource.username=your-username
spring.datasource.password=your-password
spring.jpa.database-platform=org.hibernate.dialect.PostgreSQLDialect

@Entity
@Table(name = "users")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;
    private String email;

    // 省略构造方法、getter和setter
}

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    // 可以在这里定义自定义的数据库操作方法
}

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

    public List<User> getAllUsers() {
        return userRepository.findAll();
    }

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

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

    public void deleteUser(Long id) {
        userRepository.deleteById(id);
    }
}