Question

我试图从网络获取当前时间，以便我的应用程序可以在文本视图中显示时间。但是，时间有时只会归还给我，我无法弄清楚原因。

我使用AsyncTask在单独的线程上联系time-a.nist.gov，然后用结果更新我的文本视图。这是第一次我的应用程序启动时有效，有时是第二次，但之后我注意到我一直卡在这条线上：

TimeInfo timeInfo = timeClient.getTime（inetAddress）;

我没有得到异常，以下日志语句都没有通过，没有。它只是挂起，我的文本视图是空白的。这是我的代码：

public static final String TIME_SERVER = "time-a.nist.gov";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_rtc_test);

    networkTimeTextView = (TextView) findViewById(R.id.tv_current_network_time);

    new GetTimeFromNetwork().execute();

}

public class GetTimeFromNetwork extends AsyncTask<Date, Void, Date> {

    @Override
    protected Date doInBackground(Date... params) {

        Log.i("RTCTestActivity", "Getting time...");
        try {
            NTPUDPClient timeClient = new NTPUDPClient();

            Log.i("RTCTestActivity", "Getting inet address..");
            InetAddress inetAddress = InetAddress.getByName(TIME_SERVER);

            Log.i("RTCTestActivity", "Getting time info..");
            TimeInfo timeInfo = timeClient.getTime(inetAddress);

            Log.i("RTCTestActivity", "Got time info");

            long networkTimeLong = timeInfo.getMessage().getTransmitTimeStamp().getTime();

            Date networkTimeDate = new Date(networkTimeLong);
            Log.i("time", "Time from " + TIME_SERVER + ": " + networkTimeDate);

            return networkTimeDate;

        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }

    @Override
    protected void onPostExecute(Date result) {
        super.onPostExecute(result);

        if (result == null) {

            Toast.makeText(RTCTestActivity.this, "Not connected to internet", Toast.LENGTH_SHORT).show();
            return;
        }

        String networkTimeString = "Network time: " + timeFormat.format(result);
        Log.v("RTCTestActivity", "Network time formatted: " + networkTimeString);

        networkTimeTextView.setText(networkTimeString);

    }
}

再一次，它将获取一次或两次网络时间（有时甚至完全没有），并且每次在网络时间之后只停留在上面一行，就像没有打印出来一样＃34;得到时间信息＆＃34;甚至是一个例外。有什么想法吗？

Answer 1

我找到了解决方案。看来我的连接超时，然后我的程序不知道如何处理它。我通过向NTPUDPClient添加DefaultTimeout然后将我的连接请求放入循环来解决了这个问题。如果超时，我会尝试重新连接。

修复程序位于doInBackground（）。

/** Async task to get time from the network. */
private class GetTimeFromNetwork extends AsyncTask<String, Void, String> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        // Inform user that we are connecting to the network.
        // Only do this on create, or else it will look strange to the user.
        if (!broadcastingNetworkTime) setNetworkTime("Connecting...");
    }

    @Override
    protected String doInBackground(String... params) {

        Log.i("RTCTestActivity", "Connecting to network...");

        // Client for getting time from network.
        NTPUDPClient timeClient = new NTPUDPClient();
        timeClient.setDefaultTimeout(1000);

        // Connect to network. Try again on timeout (max 6).
        for (int retries = 7; retries >= 0; retries--) {

            try {

                // Try connecting to network to get time. May timeout.
                InetAddress inetAddress = InetAddress.getByName(TIME_SERVER);
                TimeInfo timeInfo = timeClient.getTime(inetAddress);
                long networkTimeLong = timeInfo.getMessage().getTransmitTimeStamp().getTime();

                // Convert long to Date, and Date to String. Log results.
                Date networkTimeDate = new Date(networkTimeLong);
                String networkTimeString = networkTimeFormat.format(networkTimeDate);
                Log.i("Time", "Time from " + TIME_SERVER + ": " + networkTimeDate);

                // Return resulting time as a String.
                return networkTimeString;

            } catch (IOException e) {

                // Max of 6 retries.
                Log.i("RTCTestActivity", "Unable to connect. Retries left: " + (retries-1));
            }
        }

        // Unable to connect to network.
        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);

        if (result == null) {

            // Not found. Disconnected from internet or too many timeouts.
            Toast.makeText(RTCTestActivity.this, "Unable to get network time.", Toast.LENGTH_SHORT).show();
            setNetworkTime("Unavailable");
            return;
        }

        // Display resulting time in text view.
        setNetworkTime(result);

    }

} // end async task

我在某些时候也将我的返回类型更改为String，但这不应该造成太大的差别。这个解决方案对我来说始终如一，而且我还没有遇到任何问题。

从网络中获取时间 - TimeInfo没有回复？

1 个答案: