我有这个正确的代码。而且我不了解spring如何为Environment接口找到bean。帮我。谢谢

@Configuration
@ComponentScan(value = "ru.itis")
@PropertySource("application.properties")
public class AppConfig {

    @Autowired
    private Environment environment;

    @Bean
    public NamedParameterJdbcTemplate template() {
        return new NamedParameterJdbcTemplate(dataSource());
    }

    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassname(environment.getProperty("jdbc.driver"));
        dataSource.setUrl(environment.getProperty("jdbc.url"));
        dataSource.setusername(environment.getProperty("jdbc.username"));
        dataSource.setPassword(environment.getProperty("jdbc.password"));
        return dataSource;
    }
}