我在跟踪https://spring.io/guides/gs/relational-data-access/ 所以在我的主要课堂上我有：

@SpringBootApplication
@ComponentScan(basePackages = {"com.example"})
public class SpringGuideApplication implements CommandLineRunner {
    private static final Logger log = LoggerFactory.getLogger(SpringGuideApplication.class);

    @Autowired
    JdbcTemplate jdbcTemplate;

    public static void main(String[] args) {
        SpringApplication.run(SpringGuideApplication.class, args);
    }

    @Override
    public void run(String... strings) throws Exception {
        log.info("Creating tables");
        jdbcTemplate.execute("DROP TABLE clients IF EXISTS");
    }
}

此时我收到了一个错误：

***************************

APPLICATION FAILED TO START

***************************

Description:

Field jdbcTemplate in com.example.spring_guide.SpringGuideApplication required a bean of type 'org.springframework.jdbc.core.JdbcTemplate' that could not be found.

The injection point has the following annotations:
    - @org.springframework.beans.factory.annotation.Autowired(required=true)

Action:

Consider defining a bean of type 'org.springframework.jdbc.core.JdbcTemplate' in your configuration.

Process finished with exit code 1

我理解错误，但要创造 @Bean JdbcTemplate 我需要使用：

@Bean
public JdbcTemplate jdbcTemplate(DataSource dataSource) {
    return new JdbcTemplate(dataSource);
}

但我不想要，我不想要 dataSource 文件，我想有刚刚在内存数据库。有没有办法创造 JdbcTemplate 豆子没有 DataSource ? 这个教程有什么用？
在pom.xml中，现在我有：

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jdbc</artifactId>
    <version>5.2.10.RELEASE</version>
</dependency>

但也尝试过

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
    <version>2.4.0</version>
</dependency>

没有成功。