这可能是由于配置文件无法正确加载而导致的。您可以尝试在启动应用程序之前调用Apollo配置的init方法，并检查日志以查看加载是否成功。另外，您也可以检查配置文件是否命名正确，并且键和值是否匹配。以下是一些可能有用的示例代码：

public class MyApp {
    private static final Logger logger = LoggerFactory.getLogger(MyApp.class);

    public static void main(String[] args) {
        Config config = ConfigService.getAppConfig();
        config.addChangeListener(changeEvent -> logger.info("Config changed:{}", changeEvent));
        ApolloConfigChangeListener apolloConfigChangeListener = new ApolloConfigChangeListener();
        config.addChangeListener(apolloConfigChangeListener);

        while (true) {
            try {
                TimeUnit.SECONDS.sleep(60);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    static class ApolloConfigChangeListener implements ConfigChangeListener {
        private static final Logger logger = LoggerFactory.getLogger(ApolloConfigChangeListener.class);

        @Override
        public void onChange(ConfigChangeEvent changeEvent) {
            logger.info("Changes for namespace {}", changeEvent.getNamespace());
            for (String key : changeEvent.changedKeys()) {
                ConfigChange configChange = changeEvent.getChange(key);
                logger.info("Change - key:{}  oldValue:{}  newValue:{}  changeType:{}", configChange.getPropertyName(),
                        configChange.getOldValue(), configChange.getNewValue(), configChange.getChangeType());
            }
        }
    }
}