java - 安卓蓝牙字符串接收器

Question

我希望你能帮助我让这个蓝牙接收器正常工作。 我要接收的字符串是由带有 HC-06 蓝牙模块的 Arduino Uno 发送的，我可以在多个蓝牙终端应用程序中接收它。

我尝试接收的字符串如下所示:#id=3,temp=100,maxtemp=103,rpm=27,maxrpm=27* 但我只收到这样的数据:

07-21 12:45:17.959  31174-31174/fabian.d.de.rc_telemetrie_test D/BT﹕ Empfangen: 4*
07-21 12:45:18.141  31174-31174/fabian.d.de.rc_telemetrie_test D/BT﹕ Empfangen: p=83maxtemp=149rpm=34maxrpm=34*
07-21 12:45:18.471  31174-31174/fabian.d.de.rc_telemetrie_test D/BT﹕ Empfangen: 34*
07-21 12:45:18.583  31174-31174/fabian.d.de.rc_telemetrie_test D/BT﹕ Empfangen: 2maxrpm=34*
07-21 12:45:18.761  31174-31174/fabian.d.de.rc_telemetrie_test D/BT﹕ Empfangen: 4*
07-21 12:45:18.911  31174-31174/fabian.d.de.rc_telemetrie_test D/BT﹕ Empfangen: 34*
07-21 12:45:19.237  31174-31174/fabian.d.de.rc_telemetrie_test D/BT﹕ Empfangen: m=17maxrpm=34*
07-21 12:45:19.388  31174-31174/fabian.d.de.rc_telemetrie_test D/BT﹕ Empfangen: =29maxrpm=34*

这是我的蓝牙处理程序。我希望你能帮助我找到问题所在。

bluetoothIn = new Handler() {
    public void handleMessage(android.os.Message msg) {
        if (msg.what == handlerState) {
            String readMessage = (String) msg.obj;
            recDataString.append(readMessage);
            int endOfLineIndex = recDataString.indexOf("*");
            if (endOfLineIndex > 0) {
                String dataInPrint = recDataString.substring(0, endOfLineIndex);
                txtString.setText("Daten Empfangen: = " + dataInPrint);
                int dataLength = dataInPrint.length();
                txtStringLength.setText("Datenlänge: = " + String.valueOf(dataLength));

                Log.d("BT", "Received: " + recDataString);
                if (recDataString.charAt(0) == '#')
                {
                    Log.d("BT", "Matching string received: " + recDataString);
                    String[] parts = recDataString.split(",");
                    for (String part : parts) {
                        if (part.startsWith("temp=")) {
                            strTemp = part;
                            strTemp = strTemp.substring(5);
                        }
                        else if (part.startsWith("maxtemp=")) {
                            strMaxtemp = part;
                            strMaxtemp = strMaxtemp.substring(8);
                        }
                        else if (part.startsWith("rpm=")) {
                            strRpm = part;
                            strRpm = strRpm.substring(4);
                        }
                        else if (part.startsWith("maxrpm=")) {
                            strMaxrpm = part;
                            strMaxrpm = strMaxrpm.substring(7);
                        }
                    }
                    sensorView0.setText(" Temperatur: " + strTemp + "°C");  //update the textviews with sensor values
                    sensorView1.setText(" maximale Temperatur: " + strMaxtemp + "°C");
                    sensorView2.setText(" RPM: " + strRpm + "/min");
                    sensorView3.setText(" maximale RPM: " + strMaxrpm + "/min");
                }
                recDataString.delete(0, recDataString.length());                    //clear all string data
            }
        }
};

编辑:这是我的连接线程:

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

    //creation of the connect thread
    public ConnectedThread(BluetoothSocket socket) {
        InputStream tmpIn = null;
        OutputStream tmpOut = null;

        try {
            //Create I/O streams for connection
            tmpIn = socket.getInputStream();
            tmpOut = socket.getOutputStream();
        } catch (IOException e) { }

        mmInStream = tmpIn;
        mmOutStream = tmpOut;
    }


    public void run() {
        byte[] buffer = new byte[256];
        int bytes;

        // Keep looping to listen for received messages
        while (true) {
            try {
                bytes = mmInStream.read(buffer);            //read bytes from input buffer
                String readMessage = new String(buffer, 0, bytes);
                // Send the obtained bytes to the UI Activity via handler
                bluetoothIn.obtainMessage(handlerState, bytes, -1, readMessage).sendToTarget();
            } catch (IOException e) {
                break;
            }
        }
    }
    //write method
    public void write(String input) {
        byte[] msgBuffer = input.getBytes();           //converts entered String into bytes
        try {
            mmOutStream.write(msgBuffer);                //write bytes over BT connection via outstream
        } catch (IOException e) {
            //if you cannot write, close the application
            Toast.makeText(getBaseContext(), "Connection Failure", Toast.LENGTH_LONG).show();
            finish();

        }
    }
}

Answer 1

显然你的逻辑似乎没问题。来自 frarugi87 的提示可能会使它更稳定。

在过去使用 BlueToothChat 示例代码时，我遇到了类似的问题。确定的根本原因是:

• 语句bytes = mmInStream.read(buffer);是一个阻塞
  称呼。它仅在通过
  接收到一些数据后才返回到下一行 蓝牙。

• 两次连续返回之间的时间是不可预测的， 并且每次返回的字符数也是随机的。

• 当此类事件传递给处理程序时， UI 线程无法以相同的速度处理这些事件。

得到的解决方案是:

1. 不要每次都将字符串发送给处理程序，即避免在每次阻塞调用返回后发送字符串。
2. 相反，继续累积传入的字符串，直到识别出完整的数据包。
3. 只将完整的数据包传递给处理程序。这减少了 UI 线程的调用频率。