定期发送数据到服务器 [英] Periodically send data to server

问题描述

我正在开发一个通过蓝牙从Arduino接收数据并将其发送到服务器的应用程序。我已经完成了这部分的工作-用户按下按钮后，我将启动BT连接，接收数据并通过异步任务将其发送到服务器：

I'm working on an app that receives data from Arduino through Bluetooth and sends that data to server. I've got this part working - once a user presses a button, I initiate BT connection, receive data and send it to server via Async Task:

1. 用于接收数据的线程：

1. Thread for receiving data:

private class ConnectedThread extends Thread {
private final InputStream mmInStream;
private final OutputStream mmOutStream;

public ConnectedThread(BluetoothSocket socket) {

    InputStream tmpIn = null;
    OutputStream tmpOut = null;

    try {
        tmpIn = socket.getInputStream();
        tmpOut = socket.getOutputStream();
    } catch (IOException e) { }

    mmInStream = tmpIn;
    mmOutStream = tmpOut;
}

public void run() {
    Log.i("test", "Connected thread RUN");
    byte[] buffer = new byte[256];
    int bytes;

    // Keep listening to the InputStream until an exception occurs
    while (true) {
        try {
            Log.i("test", "Trying....");
            bytes = mmInStream.read(buffer);
            handler.obtainMessage(RECIEVE_MESSAGE, bytes, -1, buffer).sendToTarget();
        } catch (IOException e) {
            break;
        }
    }
}

public void write(String message) {
    Log.d(TAG, "...Data to send: " + message + "...");
    byte[] msgBuffer = message.getBytes();
    try {
        mmOutStream.write(msgBuffer);
    } catch (IOException e) {
        Log.d(TAG, "...Error data send: " + e.getMessage() + "...");
    }
}

}

ConnectedThread处理程序（接收数据，启动AsyncTask）：

ConnectedThread handler (receives data, starts AsyncTask):

private final Handler handler = new Handler() {
    public void handleMessage(android.os.Message msg) {
        switch (msg.what) {
            case RECIEVE_MESSAGE:
                byte[] readBuf = (byte[]) msg.obj;
                //String readMessage = new String(readBuf, 0, msg.arg1);
                String strIncom = new String(readBuf, 0, msg.arg1);
                sb.append(strIncom);
                int endOfLineIndex = sb.indexOf("\r\n");
                if (endOfLineIndex > 0) {
                    String sbprint = sb.substring(0, endOfLineIndex);
                    sb.delete(0, sb.length());
                    Log.i("test", "sbprint: " + sbprint);
                    sendDataToServer(sbprint);
                    txtData.setText("Data from Arduino: " + sbprint);
                }
                break;
        }
    };

};

sendDataToServer方法：

sendDataToServer method:

private void sendDataToServer(String dataToSend){
    if(dataToSend != null && !dataToSend.equals("")) {
        sendDataAsyncTask = new SendDataAsyncTask(MyActivity.this, dataToSend);
        sendDataAsyncTask.setSendDataListener(MyActivity.this);
        sendDataAsyncTask.execute();
    }
}

这或多或少有效。但是，现在我需要每两分钟重复一次该过程。我已经使用TimerTask了，但是当设备进入睡眠状态时，任务当然会停止运行。

This, more or less works. However, now I need to repeat the process every two minutes. I've got it working with TimerTask, but of course the task stops running when device goes to sleep.

我猜我需要一个服务和/或一个AlarmManager每两分钟唤醒一次设备并运行上面的代码？有什么提示吗？

I'm guessing I need a Service and / or an AlarmManager to wake the device every two minutes and run the above code? Any tips for this?

推荐答案

是的，没错。您需要实现 Service 来执行后台工作，即即使您的应用程序不在前台或设备显示关闭，也要向服务器发送数据。

Yes, that's right. You need to implement a Service to do the background job, that is to execute sending data to server, even when your app is not on foreground or device display turning off.

您可以在此处使用我的示例代码之一： https://xjaphx.wordpress.com/2012/07/07/create-a-service-that-does-a-schedule-task/

You can use one of my example code here: https://xjaphx.wordpress.com/2012/07/07/create-a-service-that-does-a-schedule-task/

此外，如果要使 Service 处于最佳状态（即，使确保它没有被系统杀死），您需要通过以下方式对其进行频繁检查：

Additionally, if you want to make the Service running in the best condition (that is, make sure it is not killed by system), you need to check it frequently by

• 实施 BOOT_RECEIVED Intent （ BroadcastReceiver ），用于在设备启动时启动您的应用。

• Implement a BOOT_RECEIVED Intent, a BroadcastReceiver, to launch your app when device is started.

注册 AlarmManager 以计划是否检查服务是否在运行；如果它已经死了，则可以重新启动（唤醒）。

Register for an AlarmManager to schedule check whether the Service is running or not; if it dies already, you can re-start (wake) it up.

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