[英]Send data from my App android to my Raspberry PI 3
嗨，我實際上正在開發應用程序，以在我的Raspberry PI 3的終端上發送命令行。
我想在按下保存按鈕時將命令“ ls”發送到我的RPI3。
手動地，我的對象BluetoothconnectionService遇到了一些問題。 我認為我無法發送數據，因為未在活動“ Accueil”上聲明我的對象？ `
BluetoothConnectionService.java：
public class BluetoothConnectionService {
private static final String TAG = "BluetoothConnectionServ";
private static final String appName = "MYAPP";
private static final UUID MY_UUID_INSECURE = UUID.fromString("8ce255c0-200a-11e0-ac64-0800200c9a66");
private final BluetoothAdapter mBluetoothAdapter;
private ConnectedThread mConnectedThread;
private AcceptThread mInsecureAcceptThread;
private ConnectThread mConnectThread;
private BluetoothDevice mmDevice;
private UUID deviceUUID;
ProgressDialog mProgressDialog;
Context mContext;
public BluetoothConnectionService(Context context) {
mContext = context;
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
start();
}
private class AcceptThread extends Thread {
// The local server socket
private final BluetoothServerSocket mmServerSocket;
private BluetoothSocket socket = null;
private InputStream mmInStream;
private String device;
public AcceptThread(){
BluetoothServerSocket tmp = null;
// Create a new listening server socket
try{
tmp = mBluetoothAdapter.listenUsingInsecureRfcommWithServiceRecord(appName, MY_UUID_INSECURE);
Log.d(TAG, "AcceptThread: Setting up Server using: " + MY_UUID_INSECURE);
}catch (IOException e){
Log.e(TAG, "AcceptThread: IOException: " + e.getMessage() );
}
mmServerSocket = tmp;
}
public void run(){
Log.d(TAG, "run: AcceptThread Running.");
BluetoothSocket socket = null;
try{
// This is a blocking call and will only return on a
// successful connection or an exception
Log.d(TAG, "run: RFCOM server socket start.....");
socket = mmServerSocket.accept();
Log.d(TAG, "run: RFCOM server socket accepted connection.");
}catch (IOException e){
Log.e(TAG, "AcceptThread: IOException: " + e.getMessage() );
}
//talk about this is in the 3rd
if(socket != null){
connected(socket,mmDevice);
}
Log.i(TAG, "END mAcceptThread ");
}
public void cancel() {
Log.d(TAG, "cancel: Canceling AcceptThread.");
try {
mmServerSocket.close();
} catch (IOException e) {
Log.e(TAG, "cancel: Close of AcceptThread ServerSocket failed. " + e.getMessage() );
}
}
}
private class ConnectThread extends Thread {
private BluetoothSocket mmSocket;
public ConnectThread(BluetoothDevice device, UUID uuid) {
Log.d(TAG, "ConnectThread: started.");
mmDevice = device;
deviceUUID = uuid;
}
public void run(){
BluetoothSocket tmp = null;
Log.i(TAG, "RUN mConnectThread ");
// Get a BluetoothSocket for a connection with the
// given BluetoothDevice
try {
Log.d(TAG, "ConnectThread: Trying to create InsecureRfcommSocket using UUID: "
+MY_UUID_INSECURE );
tmp = mmDevice.createRfcommSocketToServiceRecord(deviceUUID);
} catch (IOException e) {
Log.e(TAG, "ConnectThread: Could not create InsecureRfcommSocket " + e.getMessage());
}
mmSocket = tmp;
// Always cancel discovery because it will slow down a connection
mBluetoothAdapter.cancelDiscovery();
// Make a connection to the BluetoothSocket
try {
// This is a blocking call and will only return on a
// successful connection or an exception
mmSocket.connect();
Log.d(TAG, "run: ConnectThread connected.");
} catch (IOException e) {
// Close the socket
try {
mmSocket.close();
Log.d(TAG, "run: Closed Socket.");
} catch (IOException e1) {
Log.e(TAG, "mConnectThread: run: Unable to close connection in socket " + e1.getMessage());
}
Log.d(TAG, "run: ConnectThread: Could not connect to UUID: " + MY_UUID_INSECURE );
}
//will talk about this in the 3rd video
connected(mmSocket,mmDevice);
}
public void cancel() {
try {
Log.d(TAG, "cancel: Closing Client Socket.");
mmSocket.close();
} catch (IOException e) {
Log.e(TAG, "cancel: close() of mmSocket in Connectthread failed. " + e.getMessage());
}
}
}
public synchronized void start() {
Log.d(TAG, "start");
// Cancel any thread attempting to make a connection
if (mConnectThread != null) {
mConnectThread.cancel();
mConnectThread = null;
}
if (mInsecureAcceptThread == null) {
mInsecureAcceptThread = new AcceptThread();
mInsecureAcceptThread.start();
}
}
public void startClient(BluetoothDevice device,UUID uuid){
Log.d(TAG, "startClient: Started.");
//initprogress dialog
mProgressDialog = ProgressDialog.show(mContext,"Connecting Bluetooth"
,"Please Wait...",true);
mConnectThread = new ConnectThread(device, uuid);
mConnectThread.start();
}
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket) {
Log.d(TAG, "ConnectedThread: Starting.");
mmSocket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
int error=2;
int i;
//dismiss the progressdialog when connection is established
try{
mProgressDialog.dismiss();
error=1;
}catch (NullPointerException e){
e.printStackTrace();
error=0;
}
try {
tmpIn = mmSocket.getInputStream();
tmpOut = mmSocket.getOutputStream();
} catch (IOException e) {
e.printStackTrace();
}
mmInStream = tmpIn;
mmOutStream = tmpOut;
}
public void run(){
byte[] buffer = new byte[1024]; // 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);
final String strReceived = new String(buffer,0,bytes);
final String strByteCnt = String.valueOf(bytes) + "bytes received. \n";
// Send the obtained bytes to the UI activity
} catch (IOException e) {
Log.e(TAG, "write: Error reading Input Stream. " + e.getMessage() );
break;
}
}
}
//Call this from the main activity to send data to the remote device
public void write(byte[] bytes) {
try {
mmOutStream.write(bytes);
} catch (IOException e) {
Log.e(TAG, "write: Error writing to output stream. " + e.getMessage() );
}
}
/* Call this from the main activity to shutdown the connection */
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) { }
}
}
private void connected(BluetoothSocket mmSocket, BluetoothDevice mmDevice) {
Log.d(TAG, "connected: Starting.");
// Start the thread to manage the connection and perform transmissions
mConnectedThread = new ConnectedThread(mmSocket);
mConnectedThread.start();
}
public void write(byte[] out) {
// Create temporary object
ConnectedThread r;
// Synchronize a copy of the ConnectedThread
Log.d(TAG, "write: Write Called.");
//perform the write
mConnectedThread.write(out);
}
}
MainActivity.java：`
public class MainActivity extends AppCompatActivity implements AdapterView.OnItemClickListener{
// variables
private static final String TAG = "MainActivity";
private Uri[] mFileUris = new Uri[10];
private static final UUID MY_UUID_INSECURE = UUID.fromString("8ce255c0-200a-11e0-ac64-0800200c9a66");
public ArrayList<BluetoothDevice> mBTDevices = new ArrayList<>();
public DeviceListAdapter mDeviceListAdapter;
// Bluetooth object
BluetoothAdapter mBluetoothAdapter;
BluetoothConnectionService mBluetoothConnection;
BluetoothDevice mBTDevice;
// variables button
Button btnStartConnection;
Button scan;
// Image button
ImageButton btnONOFF;
// Variables affichages
StringBuilder messages;
ListView lvNewDevices;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Constructor
mBTDevices = new ArrayList<>();
messages = new StringBuilder();
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_BOND_STATE_CHANGED);
// list findViewbyID
btnONOFF = (ImageButton) findViewById(R.id.bluetooth_on_off);
scan = (Button) findViewById(R.id.scan);
btnStartConnection = (Button) findViewById(R.id.Connect);
lvNewDevices = (ListView) findViewById(R.id.lvNewDevices);
// divers
registerReceiver(mBroadcastReceiver4, filter);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
lvNewDevices.setOnItemClickListener(MainActivity.this);
// ON/OFF BLUETOOTH
btnONOFF.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
enableDisableBT();
}
});
// SCAN
scan.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
btnDiscover();
btnEnableDisable_Discoverable();
}
});
// CONNECTION
btnStartConnection.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
startConnection();
}
});
}
// 4 BroadcastReceiver
// Create a BroadcastReceiver for ACTION_FOUND
private final BroadcastReceiver mBroadcastReceiver1 = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// When discovery finds a device
if (action.equals(mBluetoothAdapter.ACTION_STATE_CHANGED)) {
final int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, mBluetoothAdapter.ERROR);
switch(state){
case BluetoothAdapter.STATE_OFF:
Log.d(TAG, "onReceive: STATE OFF");
break;
case BluetoothAdapter.STATE_TURNING_OFF:
Log.d(TAG, "mBroadcastReceiver1: STATE TURNING OFF");
break;
case BluetoothAdapter.STATE_ON:
Log.d(TAG, "mBroadcastReceiver1: STATE ON");
break;
case BluetoothAdapter.STATE_TURNING_ON:
Log.d(TAG, "mBroadcastReceiver1: STATE TURNING ON");
break;
}
}
}
};
private final BroadcastReceiver mBroadcastReceiver2 = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (action.equals(BluetoothAdapter.ACTION_SCAN_MODE_CHANGED)) {
int mode = intent.getIntExtra(BluetoothAdapter.EXTRA_SCAN_MODE, BluetoothAdapter.ERROR);
switch (mode) {
//Device is in Discoverable Mode
case BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE:
Log.d(TAG, "mBroadcastReceiver2: Discoverability Enabled.");
break;
//Device not in discoverable mode
case BluetoothAdapter.SCAN_MODE_CONNECTABLE:
Log.d(TAG, "mBroadcastReceiver2: Discoverability Disabled. Able to receive connections.");
break;
case BluetoothAdapter.SCAN_MODE_NONE:
Log.d(TAG, "mBroadcastReceiver2: Discoverability Disabled. Not able to receive connections.");
break;
case BluetoothAdapter.STATE_CONNECTING:
Log.d(TAG, "mBroadcastReceiver2: Connecting....");
break;
case BluetoothAdapter.STATE_CONNECTED:
Log.d(TAG, "mBroadcastReceiver2: Connected.");
break;
}
}
}
};
private BroadcastReceiver mBroadcastReceiver3 = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
Log.d(TAG, "onReceive: ACTION FOUND.");
if (action.equals(BluetoothDevice.ACTION_FOUND)){
BluetoothDevice device = intent.getParcelableExtra (BluetoothDevice.EXTRA_DEVICE);
mBTDevices.add(device);
Log.d(TAG, "onReceive: " + device.getName() + ": " + device.getAddress());
mDeviceListAdapter = new DeviceListAdapter(context, R.layout.device_adapter_view, mBTDevices);
lvNewDevices.setAdapter(mDeviceListAdapter);
}
}
};
/**
* Broadcast Receiver that detects bond state changes (Pairing status changes)
*/
private final BroadcastReceiver mBroadcastReceiver4 = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if(action.equals(BluetoothDevice.ACTION_BOND_STATE_CHANGED)){
BluetoothDevice mDevice = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
//3 cases:
//case1: bonded already
if (mDevice.getBondState() == BluetoothDevice.BOND_BONDED){
Log.d(TAG, "BroadcastReceiver: BOND_BONDED.");
//inside BroadcastReceiver4
mBTDevice = mDevice;
}
//case2: creating a bone
if (mDevice.getBondState() == BluetoothDevice.BOND_BONDING) {
Log.d(TAG, "BroadcastReceiver: BOND_BONDING.");
}
//case3: breaking a bond
if (mDevice.getBondState() == BluetoothDevice.BOND_NONE) {
Log.d(TAG, "BroadcastReceiver: BOND_NONE.");
}
}
}
};
//create method for starting connection
public void startConnection(){
startBTConnection(mBTDevice,MY_UUID_INSECURE);
goToAcceuil();
}
public void startBTConnection(BluetoothDevice device, UUID uuid){
Log.d(TAG, "startBTConnection: Initializing RFCOM Bluetooth Connection.");
mBluetoothConnection.startClient(device,uuid);
}
public void enableDisableBT(){
if(mBluetoothAdapter == null){
Log.d(TAG, "enableDisableBT: Does not have BT capabilities.");
}
if(!mBluetoothAdapter.isEnabled()){
Log.d(TAG, "enableDisableBT: enabling BT.");
Intent enableBTIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivity(enableBTIntent);
IntentFilter BTIntent = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(mBroadcastReceiver1, BTIntent);
}
if(mBluetoothAdapter.isEnabled()){
Log.d(TAG, "enableDisableBT: disabling BT.");
mBluetoothAdapter.disable();
IntentFilter BTIntent = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(mBroadcastReceiver1, BTIntent);
}
}
public void btnEnableDisable_Discoverable() {
Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
startActivity(discoverableIntent);
IntentFilter intentFilter = new IntentFilter(mBluetoothAdapter.ACTION_SCAN_MODE_CHANGED);
registerReceiver(mBroadcastReceiver2,intentFilter);
}
public void btnDiscover() {
Log.d(TAG, "btnDiscover: Looking for unpaired devices.");
if(mBluetoothAdapter.isDiscovering()){
mBluetoothAdapter.cancelDiscovery();
Log.d(TAG, "btnDiscover: Canceling discovery.");
//check BT permissions in manifest
checkBTPermissions();
mBluetoothAdapter.startDiscovery();
IntentFilter discoverDevicesIntent = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mBroadcastReceiver3, discoverDevicesIntent);
}
if(!mBluetoothAdapter.isDiscovering()){
//check BT permissions in manifest
checkBTPermissions();
mBluetoothAdapter.startDiscovery();
IntentFilter discoverDevicesIntent = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mBroadcastReceiver3, discoverDevicesIntent);
}
}
/**
* This method is required for all devices running API23+
* Android must programmatically check the permissions for bluetooth. Putting the proper permissions
* in the manifest is not enough.
*
* NOTE: This will only execute on versions > LOLLIPOP because it is not needed otherwise.
*/
private void checkBTPermissions() {
if(Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP){
int permissionCheck = this.checkSelfPermission("Manifest.permission.ACCESS_FINE_LOCATION");
permissionCheck += this.checkSelfPermission("Manifest.permission.ACCESS_COARSE_LOCATION");
if (permissionCheck != 0) {
this.requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.ACCESS_COARSE_LOCATION}, 1001); //Any number
}
}else{
Log.d(TAG, "checkBTPermissions: No need to check permissions. SDK version < LOLLIPOP.");
}
}
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
//first cancel discovery because its very memory intensive.
mBluetoothAdapter.cancelDiscovery();
Log.d(TAG, "onItemClick: You Clicked on a device.");
String deviceName = mBTDevices.get(i).getName();
String deviceAddress = mBTDevices.get(i).getAddress();
Log.d(TAG, "onItemClick: deviceName = " + deviceName);
Log.d(TAG, "onItemClick: deviceAddress = " + deviceAddress);
//create the bond.
//NOTE: Requires API 17+? I think this is JellyBean
if(Build.VERSION.SDK_INT > Build.VERSION_CODES.JELLY_BEAN_MR2){
Log.d(TAG, "Trying to pair with " + deviceName);
mBTDevices.get(i).createBond();
mBTDevice = mBTDevices.get(i);
mBluetoothConnection = new BluetoothConnectionService(MainActivity.this);
}
}
public void goToAcceuil (){
Intent intent = new Intent (this,Accueil.class);
intent.putExtra("DEVICE_NAME", mBTDevice.getName());
intent.putExtra("DEVICE_ADRESS", mBTDevice.getAddress());
intent.putExtra("mBTDevice",mBTDevice);
//intent.putExtra("mBluetoothConnection",mBluetoothConnection);
startActivity(intent);
}
protected void onDestroy() {
Log.d(TAG, "onDestroy: called.");
super.onDestroy();
unregisterReceiver(mBroadcastReceiver1);
unregisterReceiver(mBroadcastReceiver2);
unregisterReceiver(mBroadcastReceiver3);
unregisterReceiver(mBroadcastReceiver4);
}
}
Accueil.java：
public class Accueil extends AppCompatActivity {
// Bluetooth
BluetoothConnectionService mBluetoothConnection;
BluetoothDevice mBTDevice;
// String
String name_device1;
String adress_device1;
String freq_value1;
String item_spin1;
String item_spin;
// Image Button
ImageButton btn_back;
ImageButton btn_accueil;
ImageButton btn_voice;
ImageButton btn_scan;
ImageButton btn_settings;
// Button
Button btn_send_freq;
// Textview
TextView name_device;
TextView adress_device;
// Edit Text
EditText freq_value;
// List
ArrayAdapter<String> adapter;
List<String> list;
// Spinner
Spinner spinner1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_accueil);
// Variables from other activity
name_device1= getIntent().getStringExtra("DEVICE_NAME");
adress_device1=getIntent().getStringExtra("DEVICE_ADRESS");
mBTDevice=getIntent().getExtras().getParcelable("mBTDevice");
//mBluetoothConnection=getIntent().getExtras().getParcelable("mBluetoothConnection");
freq_value1=getIntent().getStringExtra("VALUE_FREQ");
item_spin1=getIntent().getStringExtra("VALUE_SPIN");
// findView by ID
name_device= (TextView) findViewById(R.id.name_device2);
adress_device= (TextView) findViewById(R.id.adress_device2);
btn_back = (ImageButton) findViewById(R.id.back1);
btn_accueil = (ImageButton) findViewById(R.id.accueil1);
btn_voice = (ImageButton) findViewById(R.id.voice1);
btn_scan = (ImageButton) findViewById(R.id.scan1);
btn_settings= (ImageButton) findViewById(R.id.settings1);
btn_send_freq = (Button) findViewById(R.id.send_freq1);
freq_value = (EditText) findViewById(R.id.value_freq1);
spinner1=(Spinner) findViewById(R.id.spinner_freq);
// SetText
name_device.setText(name_device1);
adress_device.setText(adress_device1);
freq_value.setText(freq_value1);
// Spinner
list=new ArrayList<String>();
list.add("MHz");
list.add("GHz");
adapter= new ArrayAdapter<String>(this,R.layout.spinner_item,list);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner1.setAdapter(adapter);
btn_send_freq.setOnClickListener(new View.OnClickListener() { // Bouton Save
@Override
public void onClick(View view) {
send_freq();
}
});
btn_back.setOnClickListener(new View.OnClickListener() { // Bouton RETOUR
@Override
public void onClick(View view) {
gotoBack();
}
});
btn_accueil.setOnClickListener(new View.OnClickListener() { // Bouton ACCUEIL
@Override
public void onClick(View view) {
gotoAccueil();
}
});
btn_voice.setOnClickListener(new View.OnClickListener() { // Bouton VOICE
@Override
public void onClick(View view) {
gotoVoice();
}
});
btn_scan.setOnClickListener(new View.OnClickListener() { // Bouton SCAN
@Override
public void onClick(View view) {
gotoScan();
}
});
btn_settings.setOnClickListener(new View.OnClickListener() { // Bouton SETTINGS
@Override
public void onClick(View view) {
gotoSettings();
}
});
}
// Fonction
public void send_freq()
{
byte[] bytesToSend="sudo rm azertyy".getBytes();
mBluetoothConnection.write(bytesToSend);
byte[] NewLine = "\n".getBytes();
mBluetoothConnection.write(NewLine);
}
// Fonctions onglets
public void gotoBack() // Onglet PRECEDENT
{
Intent intent = new Intent (this,MainActivity.class);
startActivity(intent);
}
public void gotoAccueil() // Onglet ACCUEIL
{
Intent intent = new Intent (this,Accueil.class);
// get selected vale and start new activity
item_spin= spinner1.getSelectedItem().toString();
intent.putExtra("DEVICE_NAME", mBTDevice.getName());
intent.putExtra("DEVICE_ADRESS", mBTDevice.getAddress());
intent.putExtra("VALUE_FREQ", freq_value.getText().toString());
intent.putExtra("VALUE_SPIN", item_spin);
intent.putExtra("mBTDevice",mBTDevice);
startActivity(intent);
}
public void gotoVoice() // Onglet VOICE
{
Intent intent = new Intent (this,voice.class);
// get selected vale and start new activity
item_spin= spinner1.getSelectedItem().toString();
intent.putExtra("DEVICE_NAME", mBTDevice.getName());
intent.putExtra("DEVICE_ADRESS", mBTDevice.getAddress());
intent.putExtra("VALUE_FREQ", freq_value.getText().toString());
intent.putExtra("VALUE_SPIN", item_spin);
intent.putExtra("mBTDevice",mBTDevice);
startActivity(intent);
}
public void gotoScan() // Onglet SCAN
{
Intent intent = new Intent (this,Scan.class);
// get selected vale and start new activity
item_spin= spinner1.getSelectedItem().toString();
intent.putExtra("DEVICE_NAME", mBTDevice.getName());
intent.putExtra("DEVICE_ADRESS", mBTDevice.getAddress());
intent.putExtra("VALUE_FREQ", freq_value.getText().toString());
intent.putExtra("VALUE_SPIN", item_spin);
intent.putExtra("mBTDevice",mBTDevice);
startActivity(intent);
}
public void gotoSettings() // Onglet SETTINGS
{
Intent intent = new Intent (this,connection.class);
// get selected vale and start new activity
item_spin= spinner1.getSelectedItem().toString();
intent.putExtra("DEVICE_NAME", mBTDevice.getName());
intent.putExtra("DEVICE_ADRESS", mBTDevice.getAddress());
intent.putExtra("VALUE_FREQ", freq_value.getText().toString());
intent.putExtra("VALUE_SPIN", item_spin);
intent.putExtra("mBTDevice",mBTDevice);
startActivity(intent);
}
}
使用此功能，我想在RPI3的終端上發送“ ls”：
public void send_freq()
{
byte[] bytesToSend="ls".getBytes();
mBluetoothConnection.write(bytesToSend);
byte[] NewLine = "\n".getBytes();
mBluetoothConnection.write(NewLine);
}
但我不明白，我有這樣的錯誤： 在此處輸入圖片描述
我嘗試使用Parcelable解決此問題，但沒有成功... 在此處輸入圖片描述
所以我的代碼不起作用。 我的應用程序一直崩潰...
謝謝你的幫助 ！
據我了解，您在MainActivity.java中有一個按鈕，可以通過Intent打開另一個Activity（Accueil.java） 。 這樣做時，您將發送帶有附加內容的Intent ，以在它們之間傳輸數據。
如果Intent實現了Parcelable接口，則它只能將一個對象作為額外對象。
在這里，您嘗試添加未實現Parcelable的 BluetoothConnectionService 。 您將其注釋掉，因為它給了您屏幕截圖中顯示的錯誤。
//intent.putExtra("mBluetoothConnection",mBluetoothConnection);
這意味着在Accueil.java中，您的mBluetoothConnection將為null，從而導致您的應用程序崩潰。
//mBluetoothConnection=getIntent().getExtras().getParcelable("mBluetoothConnection");
解決這個問題的方法是
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