我在用nutzwk的apitoken的时候，每次生成token调用getKey方法的时候，总是会报NullPointerException，说redisService是null，但是我Inject过了啊。搞不懂了。

2019-04-26 00:03:35,811 org.nutz.mvc.impl.processor.FailProcessor.process(FailPr
ocessor.java:28) WARN  - Error@/public/wx/wechat/8b5e78c086a9426db738094a7b43d47
f/back :
java.lang.NullPointerException
        at cn.wizzer.app.web.commons.utils.TokenUtil.getKey(TokenUtil.java:43)
        at cn.wizzer.app.web.commons.utils.TokenUtil.generateToken(TokenUtil.jav
a:71)
        at cn.wizzer.app.web.modules.controllers.front.wx.WechatController.back(
WechatController.java:125)

    @Inject
    private RedisService redisService;

    /**
     * 获取KEY
     *
     * @param appid appid
     * @return
     * @throws IOException
     * @throws ClassNotFoundException
     */
    private Key getKey(String appid) throws IOException, ClassNotFoundException {
        Key key;
43        byte[] obj = redisService.get(("api_token:" + appid).getBytes());
        if (obj != null) {
            ObjectInputStream keyIn = new ObjectInputStream(new ByteArrayInputStream(obj));
            key = (Key) keyIn.readObject();
            keyIn.close();
        } else {
            key = MacProvider.generateKey();
            ByteArrayOutputStream bao = new ByteArrayOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(bao);
            oos.writeObject(key);
            obj = bao.toByteArray();
            redisService.set(("api_token:" + appid).getBytes(), obj);
            redisService.expire(("api_token:" + appid).getBytes(), 7202);//2小时零2秒后自动删除
        }
        return key;
    }