Hibernate ValidationQuery设置java bean

Question

我试图在任何数据库操作之前验证查询，如果数据库连接失败，应该重新连接选项而不在数据源代码中添加属性工作正常。

以下是我的代码

@Configuration
@EnableTransactionManagement
@PropertySource({"classpath:application.properties"})
public class DatabaseConfig {

  @Value("${db.driver}")
  private String DB_DRIVER;

  @Value("${db.password}")
  private String DB_PASSWORD;

  @Value("${db.url}")
  private String DB_URL;

  @Value("${db.username}")
  private String DB_USERNAME;

  @Value("${hibernate.dialect}")
  private String HIBERNATE_DIALECT;

  @Value("${hibernate.show_sql}")
  private String HIBERNATE_SHOW_SQL;

  @Value("${hibernate.hbm2ddl.auto}")
  private String HIBERNATE_HBM2DDL_AUTO;

  @Value("${entitymanager.packagesToScan}")
  private String ENTITYMANAGER_PACKAGES_TO_SCAN;

  @Bean
  public DataSource dataSource() {
    DriverManagerDataSource dataSource = new DriverManagerDataSource();
//    DataSource dataSource = new DriverManagerDataSource();
//    org.apache.tomcat.jdbc.pool.DataSource ds = new org.apache.tomcat.jdbc.pool.DataSource();
    dataSource.setDriverClassName(DB_DRIVER);
    dataSource.setUrl(DB_URL);
    dataSource.setUsername(DB_USERNAME);
    dataSource.setPassword(DB_PASSWORD);

    Properties configProps = new Properties();
       configProps.put("db.validationQuery", "SELECT 1");
       configProps.put("db.testOnBorrow", true);
       configProps.put("testWhileIdle", true);

    dataSource.setConnectionProperties(configProps);
    return dataSource;
  }

  @Bean
  public LocalSessionFactoryBean sessionFactory() {
    LocalSessionFactoryBean sessionFactoryBean = new LocalSessionFactoryBean();
    sessionFactoryBean.setDataSource(dataSource());
    sessionFactoryBean.setPackagesToScan(ENTITYMANAGER_PACKAGES_TO_SCAN);
    Properties hibernateProperties = new Properties();
    hibernateProperties.put("hibernate.dialect", HIBERNATE_DIALECT);
    hibernateProperties.put("hibernate.show_sql", HIBERNATE_SHOW_SQL);
    hibernateProperties.put("hibernate.hbm2ddl.auto", HIBERNATE_HBM2DDL_AUTO);
    sessionFactoryBean.setHibernateProperties(hibernateProperties);

    return sessionFactoryBean;
  }

  @Bean
  public HibernateTransactionManager transactionManager() {
    HibernateTransactionManager transactionManager = 
        new HibernateTransactionManager();
    transactionManager.setSessionFactory(sessionFactory().getObject());
    return transactionManager;
  }

}

但它给了我错误

o.s.boot.SpringApplication               : Application startup failed

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'adminDAOImpl': Unsatisfied dependency expressed through field 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [com/ehydromet/dao/impl/DatabaseConfig.class]: Invocation of init method failed; nested exception is java.lang.NullPointerException