问题
I'm sending continuous data from PIC (from analog input) to the bluetooth module and then I'm trying to read them with android (in HyperTerminal I get values from 0 to 255). How could I change my code to read strings of 3 bytes and immediately display them into the TextView. Now I can display data but it's too slow and values update only when button is pressed. Here is my MainActivity.java:
public class MainActivity extends Activity {
private static final String TAG = "bluetooth2";
Button btn1, btn2, btn3, btn4;
TextView txtArduino;
Handler h;
private static final int REQUEST_ENABLE_BT = 1;
final int RECIEVE_MESSAGE = 1; // Status for Handler
private BluetoothAdapter btAdapter = null;
private BluetoothSocket btSocket = null;
private StringBuilder sb = new StringBuilder();
private ConnectedThread mConnectedThread;
// SPP UUID service
private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
// MAC-address of Bluetooth module (you must edit this line)
private static String address = "00:12:09:25:92:57";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn1 = (Button) findViewById(R.id.btn1); // activity no. 1
btn2 = (Button) findViewById(R.id.btn2); // activity no. 2
btn3 = (Button) findViewById(R.id.btn3); // activity no. 3
btn4 = (Button) findViewById(R.id.btn4); // activity no. 4
txtArduino = (TextView) findViewById(R.id.txtArduino); // for display the received data from the Arduino
h = new Handler() {
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case RECIEVE_MESSAGE:
byte[] readBuf = (byte[]) msg.obj;
String strIncom = new String(readBuf, 0, msg.arg1); // create string from bytes array
//Toast.makeText(MainActivity.this, strIncom, Toast.LENGTH_SHORT).show();
sb.append(strIncom); // append string
int endOfLineIndex = sb.indexOf("\r\n"); // determine the end-of-line
if (endOfLineIndex > 0) { // if end-of-line,
String sbprint = sb.substring(0, endOfLineIndex); // extract string
sb.delete(0, sb.length()); // and clear
txtArduino.setText("Data from PIC: " + sbprint); // update TextView
//btn2.setEnabled(true);
//btn1.setEnabled(true);
}
//Log.d(TAG, "...String:"+ sb.toString() + "Byte:" + msg.arg1 + "...");
break;
}
};
};
btAdapter = BluetoothAdapter.getDefaultAdapter(); // get Bluetooth adapter
checkBTState();
btn1.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
//btn1.setEnabled(false);
mConnectedThread.write("0"); // Send "0" via Bluetooth
//Toast.makeText(getBaseContext(), "Turn on LED", Toast.LENGTH_SHORT).show();
if(v.getId() == R.id.btn1){
//define a new Intent for the second Activity
Intent intent = new Intent(MainActivity.this,NewClass1.class);
//start the second Activity
MainActivity.this.startActivity(intent);
}}
});
btn2.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
//btn2.setEnabled(false);
mConnectedThread.write("1"); // Send "1" via Bluetooth
if(v.getId() == R.id.btn2){
//define a new Intent for the second Activity
Intent intent = new Intent(MainActivity.this,NewClass2.class);
//start the second Activity
MainActivity.this.startActivity(intent);
}}
});
btn3.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
//btn3.setEnabled(false);
mConnectedThread.write("2"); // Send "2" via Bluetooth
if(v.getId() == R.id.btn3){
//define a new Intent for the second Activity
Intent intent = new Intent(MainActivity.this,NewClass3.class);
//start the second Activity
MainActivity.this.startActivity(intent);
}}
});
btn4.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
//btn4.setEnabled(false);
mConnectedThread.write("3"); // Send "3" via Bluetooth
if(v.getId() == R.id.btn4){
//define a new Intent for the second Activity
Intent intent = new Intent(MainActivity.this,NewClass4.class);
//start the second Activity
MainActivity.this.startActivity(intent);
}}
});
}
@Override
public void onResume() {
super.onResume();
Log.d(TAG, "...onResume - try connect...");
// Set up a pointer to the remote node using it's address.
BluetoothDevice device = btAdapter.getRemoteDevice(address);
// Two things are needed to make a connection:
// A MAC address, which we got above.
// A Service ID or UUID. In this case we are using the
// UUID for SPP.
try {
btSocket = device.createRfcommSocketToServiceRecord(MY_UUID);
} catch (IOException e) {
errorExit("Fatal Error", "In onResume() and socket create failed: " + e.getMessage() + ".");
}
// Discovery is resource intensive. Make sure it isn't going on
// when you attempt to connect and pass your message.
btAdapter.cancelDiscovery();
// Establish the connection. This will block until it connects.
Log.d(TAG, "...Connecting...");
try {
btSocket.connect();
Log.d(TAG, "....Connection ok...");
} catch (IOException e) {
try {
btSocket.close();
} catch (IOException e2) {
errorExit("Fatal Error", "In onResume() and unable to close socket during connection failure" + e2.getMessage() + ".");
}
}
// Create a data stream so we can talk to server.
Log.d(TAG, "...Create Socket...");
mConnectedThread = new ConnectedThread(btSocket);
mConnectedThread.start();
}
@Override
public void onPause() {
super.onPause();
Log.d(TAG, "...In onPause()...");
try {
btSocket.close();
} catch (IOException e2) {
errorExit("Fatal Error", "In onPause() and failed to close socket." + e2.getMessage() + ".");
}
}
private void checkBTState() {
// Check for Bluetooth support and then check to make sure it is turned on
// Emulator doesn't support Bluetooth and will return null
if(btAdapter==null) {
errorExit("Fatal Error", "Bluetooth not supported");
} else {
if (btAdapter.isEnabled()) {
Log.d(TAG, "...Bluetooth ON...");
} else {
//Prompt user to turn on Bluetooth
Intent enableBtIntent = new Intent(btAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
Toast.makeText(getBaseContext(), "Connected!", Toast.LENGTH_SHORT).show();
}
}
}
private void errorExit(String title, String message){
Toast.makeText(getBaseContext(), title + " - " + message, Toast.LENGTH_LONG).show();
finish();
}
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the input and output streams, using temp objects because
// member streams are final
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) { }
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run() {
byte[] buffer = new byte[256]; // buffer store for the stream
int bytes; // bytes returned from read()
// Keep listening to the InputStream until an exception occurs
while (true) {
try {
// Read from the InputStream
bytes = mmInStream.read(buffer); // Get number of bytes and message in "buffer"
h.obtainMessage(RECIEVE_MESSAGE, bytes, -1, buffer).sendToTarget(); // Send to message queue Handler
} catch (IOException e) {
break;
}
}
}
/* Call this from the main activity to send data to the remote device */
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() + "...");
}
}
/* Call this from the main activity to shutdown the connection */
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) { }
}
}
}
And activity_main.xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:keepScreenOn="true" >
<TextView
android:id="@+id/txtArduino"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="" />
<Button
android:id="@+id/btn1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/txtArduino"
android:text="@string/btn_1" />
<Button
android:id="@+id/btn2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/btn1"
android:text="@string/btn_2" />
<Button
android:id="@+id/btn3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/btn2"
android:text="@string/btn_3" />
<Button
android:id="@+id/btn4"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/btn3"
android:text="@string/btn_4" />
</RelativeLayout>
回答1:
When I need to run something every so often I use a handler.
Handler viewHandler = new Handler();
Runnable updateView = new Runnable() {
@Override
public void run() {
mEmulatorView.invalidate();
viewHandler.postDelayed(updateView, 1000);
}
};
To call this in my method:
viewHandler.post(updateView);
In this case I am updating my screen every 1000ms by invalidating it.
EDIT: full code sample
Handler viewHandler = new Handler();
Runnable updateView = new Runnable() {
@Override
public void run() {
mEmulatorView.invalidate();
if (statusBool == true) {
for (int i = 1; i < dataReceived.length() - 1; i++) {
if (dataReceived.charAt(i) == '>') {
Log.d(TAG, "found >");
deviceStatus = 0;
}
if (dataReceived.charAt(i) == '#'
&& dataReceived.charAt(i - 1) != ')') {
Log.d(TAG, "found #");
deviceStatus = 1;
}
if ((i + 1) <= (dataReceived.length())
&& dataReceived.charAt(i) == ')'
&& dataReceived.charAt(i + 1) == '#') {
Log.d(TAG, "found config )#");
deviceStatus = 2;
}
}
statusBool = false;
viewHandler.postDelayed(updateView, 1000);
}
}
};
public void onDataReceived(int id, byte[] data) {
dataReceived = new String(data);
statusBool = true;
Log.d(TAG, "in data received " + dataReceived);
((MyBAIsWrapper) bis).renew(data);
runOnUiThread(new Runnable(){
@Override
public void run() {
mSession.write(dataReceived);
}});
viewHandler.post(updateView);
}
来源：https://stackoverflow.com/questions/14397973/how-to-read-continuous-data-and-display-it