我試圖通過自動裝配環境變量來檢索從 .yml 文件加載的屬性，但出現空指針異常：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我想以編程方式創建一個 DataSource bean，同時將詳細信息（用戶名、密碼、主機等）保留在配置文件中。這是我目前的設置：@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();  }}我不偏愛 .yml 文件格式或使用環境變量。如果有不同/更好的方法來從 .yml 文件（或其他文件格式）獲取數據，我愿意嘗試。