如何从Firestore服务器获取时间戳，而不必担心设备时钟与Firestore不同步的情况 [英] How can I get Timestamp from Firestore server without bothering for the case when device clock is out of sync with Firestore

问题描述

这是对此问题的参考 Firebase时间戳当前时间戳和数据库时间戳错误之间的区别

如果我使用 Timestamp.now()，在某些情况下设备时钟与Firestore不同步，并且我的时间计算不准确.我想从Firestore服务器获取准确的时间，而不会被不同步的情况所困扰.有什么办法可以做到吗?

If I use Timestamp.now() there are cases where the device clock is out of sync with Firestore and my time calculations are not accurate. I want to get the exact time from the Firestore server without being bothered by out of sync cases. Is there any way I could do that?

我见过 FieldValue.serverTimestamp()，但是我找不到一种使用它来计算任何东西的方法，因为它的返回类型是 FieldValue ，而且我无法解析它保存为 Timestamp .

I have seen FieldValue.serverTimestamp() but there I cannot find a way to calculate anything using it, since it's return type is FieldValue and I am unable to parse it to Timestamp.

推荐答案

一种明显但在经济上不利的方法是写入时间戳的Firestore数据库，然后从那里重新读取.

One obvious but economically adverse way is to write to Firestore Database, the timestamp and read it again from there.

db.collection("TimestampChecker").document("some_string").set(new TimestampGetter()).addOnCompleteListener(new OnCompleteListener<Void>() {
            @Override
            public void onComplete(@NonNull Task<Void> task) {

            db.collection("TimestampChecker").document("some_string").get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
                @Override
                public void onComplete(@NonNull Task<DocumentSnapshot> task) {
                    if(task.getResult()!=null)
                    {
                        TimestampGetter timestampGetter = task.getResult().toObject(TimestampGetter.class);
                        Date dateNow = timestampGetter.getTimestampNow();

                    }

                }
            });

        }
    });

TimestampGetter可以是这样的类:

And TimestampGetter can be a class like this:

public class TimestampGetter {
@ServerTimestamp
private Date timestampNow;

public TimestampGetter(Date timestampNow) {
    this.timestampNow = timestampNow;
}

public TimestampGetter() {
}

public Date getTimestampNow() {
    return timestampNow;
}

public void setTimestampNow(Date timestampNow) {
    this.timestampNow = timestampNow;
}}

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