JdbcTemplate无法连接到数据库

Question

我有一个Roles pojo类，它映射到数据库中的Roles表。 然后我有RolesDao及其实现RolesDaoImpl。  我在main（）方法中使用以下代码调用RolesDao：-

RolesDao rolesDao = context.getBean( RolesDao.class);
        rolesDao.getRolesList();

但是我得到以下错误：-

Exception in thread "main" java.lang.NullPointerException
    at com.rahul.spring.dao.RolesDaoImpl.getRolesList(RolesDaoImpl.java:35)

我该如何解决？

我的RolesDaoImpl在下面：-

@Component
public class RolesDaoImpl  extends BaseDaoImpl implements RolesDao  {

@Autowired
private OracleConfiguration dataSource;
public List<Roles> getRolesList() {

        String sql = "SELECT * FROM ROLES";
        List<Roles> customers  = getJdbcTemplate().query(sql,
                new BeanPropertyRowMapper<Roles>(Roles.class));
        return customers;
        }

我的BaseDaoImpl在下面

    @Component
    public class BaseDaoImpl {
       private JdbcTemplate jdbcTemplate; //getters and setters omitted for brevity 
        private String packageName;
public JdbcTemplate getJdbcTemplate() {
        return jdbcTemplate;
    }


    public void setDataSource ( DataSource dataSource )
    {
        this.jdbcTemplate = new JdbcTemplate(dataSource);
    }

我的OracleConfiguration类是

@Configuration
//@ConfigurationProperties("oracle")
@PropertySource("classpath:dev.properties")
public class OracleConfiguration {
     @Value( "${oracle.username}" )
    private String username;// we can remove value injection and just use 
    @Value( "${oracle.password}" )
    private String password;
 @Value( "${oracle.url}" )
    private String url;
    @Value( "${oracle.driverType}" )
    private String driverType;
    @Bean
DataSource dataSource() throws SQLException {

    OracleDataSource dataSource = new OracleDataSource();
    dataSource.setDriverType(driverType);
    dataSource.setUser(username);
    dataSource.setPassword(password);
    dataSource.setURL(url);
    dataSource.setImplicitCachingEnabled(true);
    dataSource.setFastConnectionFailoverEnabled(true);
    return dataSource;
}

我能够从dev.properties文件中打印/获取值。