我试图通过自动装配环境变量来检索从 .yml 文件加载的属性，但出现空指针异常：Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [com/example/AppConfig.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is java.lang.NullPointerException我想以编程方式创建一个 DataSource bean，同时将详细信息（用户名、密码、主机等）保留在配置文件中。这是我目前的设置：@SpringBootApplication@ImportResource({"classpath:controllers.xml"})public class WebApplication{  public static void main(String[] args){    SpringApplication.run(WebApplication.class, args);  }}server:  port: 8080database:  host: localhost  instance: db_instance  port: 3036  user: root  password: passkey@Configurationpublic class AppConfig {  @Autowired  private Environment environment;  @Bean  public DataSource dataSource() {    String url = "jdbc:mysql://" +        environment.getProperty("database.host") +        ":" + environment.getProperty("database.port") +        "/" + environment.getProperty("database.instance") +        "?serverTimezone=UTC&useSSL=false&allowPublicKeyRetrieval=true";    return DataSourceBuilder.create()        .driverClassName("com.mysql.jdbc.Driver")        .url(url)        .username(environment.getProperty("database.user"))        .password(environment.getProperty("database.password"))        .build();  }}我不偏爱 .yml 文件格式或使用环境变量。如果有不同/更好的方法来从 .yml 文件（或其他文件格式）获取数据，我愿意尝试。