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私はPOSアプリケーションを作りたいと思います。このアプリでは、私は印刷領収書をする必要があります。私はBluetooth接続に問題があります。このコードでは、私が使用しているプリンタデバイスを自分のフラグメントに設定したいと思っています。だから私は断片を移動するが、私はMainActivityにコードを入れて接続を維持するブルートゥースを作るために。しかし、問題は別のフラグメントに移動するたびに、mServiceは常にnullです。だから、私はデバイスに正しく接続できませんでした、助けてください。すでに活動中のオブジェクトを初期化するための高度な MainActivity.JavaAndroidのBluetoothプリンタ接続に失敗しました
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener{
private static final String TAG = "MainActivity";
Fragment fragment = null;
Class fragmentClass = null;
public static final int MESSAGE_STATE_CHANGE = 1;
public static final int MESSAGE_READ = 2;
public static final int MESSAGE_WRITE = 3;
public static final int MESSAGE_DEVICE_NAME = 4;
public static final int MESSAGE_TOAST = 5;
public static final int MESSAGE_CONNECTION_LOST = 6;
public static final int MESSAGE_UNABLE_CONNECT = 7;
private String mConnectedDeviceName = null;
// Key names received from the BluetoothService Handler
public static final String DEVICE_NAME = "device_name";
public static final String TOAST = "toast";
public static final int REQUEST_CONNECT_DEVICE = 1;
private static final int REQUEST_ENABLE_BT = 2;
private BluetoothAdapter mBluetoothAdapter = null;
public BluetoothService mService = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.setDrawerListener(toggle);
toggle.syncState();
NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
navigationView.setNavigationItemSelectedListener(this);
fragmentClass = RegisterFragment.class;
try {
fragment = (Fragment) fragmentClass.newInstance();
} catch (Exception e) {
e.printStackTrace();
}
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.content_main2, fragment).commit();
Log.v(TAG, "Starting DoDaily service...");
startService(new Intent(this, DoDaily.class));
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
FragmentManager fm = getSupportFragmentManager();
//if you added fragment via layout xml
if (!mBluetoothAdapter.isEnabled()) {
Intent enableIntent = new Intent(
BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
// Otherwise, setup the session
} else {
if (mService == null) {
setMService();
}
}
}
@Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
//getMenuInflater().inflate(R.menu.main2, menu);
return true;
}
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
String TAG_FRAGMENT="";
if (id == R.id.nav_regist) {
fragmentClass = RegisterFragment.class;
TAG_FRAGMENT ="register";
// Handle the camera action
} else if (id == R.id.nav_activity) {
fragmentClass = ActivityFragment.class;
TAG_FRAGMENT ="activity";
}
else if(id == R.id.nav_inventory)
{
fragmentClass = InventoryFragment.class;
TAG_FRAGMENT ="inventory";
}
else if (id == R.id.nav_manage) {
fragmentClass = SettingFragment.class;
TAG_FRAGMENT ="setting";
}
try {
fragment = (Fragment) fragmentClass.newInstance();
} catch (Exception e) {
e.printStackTrace();
}
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.content_main2, fragment,TAG_FRAGMENT).commit();
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
@SuppressLint("HandlerLeak")
private final Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MESSAGE_STATE_CHANGE:
if (DEBUG)
Log.i(TAG, "MESSAGE_STATE_CHANGE: " + msg.arg1);
switch (msg.arg1) {
case BluetoothService.STATE_CONNECTED:
//btnScan.setText(getText(R.string.Connecting));
fragment1.btnScanEnable(false);
break;
case BluetoothService.STATE_CONNECTING:
Toast.makeText(MainActivity.this,R.string.title_connecting,Toast.LENGTH_SHORT).show();
break;
case BluetoothService.STATE_LISTEN:
case BluetoothService.STATE_NONE:
Toast.makeText(MainActivity.this,R.string.title_not_connected,Toast.LENGTH_SHORT).show();
break;
}
break;
case MESSAGE_WRITE:
break;
case MESSAGE_READ:
break;
case MESSAGE_DEVICE_NAME:
// save the connected device's name
mConnectedDeviceName = msg.getData().getString(DEVICE_NAME);
Toast.makeText(MainActivity.this,"Connected to " + mConnectedDeviceName,
Toast.LENGTH_SHORT).show();
String text ="Connected to "+mConnectedDeviceName;
fragment1.setTvText(text);
break;
case MESSAGE_TOAST:
Toast.makeText(MainActivity.this, msg.getData().getString(TOAST), Toast.LENGTH_SHORT).show();
break;
case MESSAGE_CONNECTION_LOST:
Toast.makeText(MainActivity.this, "Device connection was lost",Toast.LENGTH_SHORT).show();
String text1 ="Not Connect to Any Device";
fragment1.setTvText(text1);
// editText.setEnabled(false);
// sendButton.setEnabled(false);
break;
case MESSAGE_UNABLE_CONNECT:
Toast.makeText(MainActivity.this, "Unable to connect device",
Toast.LENGTH_SHORT).show();
break;
}
}
};
@Override
public void onStart() {
super.onStart();
// If Bluetooth is not on, request that it be enabled.
// setupChat() will then be called during onActivityResult
if (!mBluetoothAdapter.isEnabled()) {
Intent enableIntent = new Intent(
BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
// Otherwise, setup the session
} else {
if (mService == null){
setMService();
}
}
}
@Override
public synchronized void onResume() {
super.onResume();
if (mService != null) {
if (mService.getState() == BluetoothService.STATE_NONE) {
// Start the Bluetooth services
mService.start();
}
}
}
@Override
public synchronized void onPause() {
super.onPause();
if (DEBUG)
Log.e(TAG, "- ON PAUSE -");
}
@Override
public void onStop() {
super.onStop();
if (DEBUG)
Log.e(TAG, "-- ON STOP --");
}
@Override
public void onDestroy() {
super.onDestroy();
// Stop the Bluetooth services
if (mService != null)
mService.stop();
if (DEBUG)
Log.e(TAG, "--- ON DESTROY ---");
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (DEBUG)
Log.d(TAG, "onActivityResult " + resultCode);
switch (requestCode) {
case REQUEST_CONNECT_DEVICE:{
// When DeviceListActivity returns with a device to connect
if (resultCode == Activity.RESULT_OK) {
// Get the device MAC address
String address = data.getExtras().getString(
DeviceListActivity.EXTRA_DEVICE_ADDRESS);
// Get the BLuetoothDevice object
if (BluetoothAdapter.checkBluetoothAddress(address)) {
BluetoothDevice device = mBluetoothAdapter
.getRemoteDevice(address);
// Attempt to connect to the device
mService.connect(device);
}
}
break;
}
case REQUEST_ENABLE_BT:{
// When the request to enable Bluetooth returns
if (resultCode == Activity.RESULT_OK) {
// Bluetooth is now enabled, so set up a session
// FragmentManager fm1 = getSupportFragmentManager();
// SettingFragment fragment1 = (SettingFragment) fm1.findFragmentByTag("setting");
// fragment1.KeyListenerInit();
setMService();
} else {
// User did not enable Bluetooth or an error occured
Log.d(TAG, "BT not enabled");
Toast.makeText(MainActivity.this, R.string.bt_not_enabled_leaving,Toast.LENGTH_SHORT).show();
onBackPressed();
}
break;
}
}
}
public void setMService()
{
mService = new BluetoothService(MainActivity.this, mHandler);
}
}
SettingFragment.Java
public class SettingFragment extends Fragment {
public static final int REQUEST_CONNECT_DEVICE = 1;
private static final String CHINESE = "GBK";
SessionManagement sessionManagement;
DatabaseHandler db;
TextView tvConnected;
Button btnScan;
Button btnTest;
public SettingFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View rootview = inflater.inflate(R.layout.fragment_setting, container, false);
getActivity().setTitle("Setting");
btnScan = (Button)rootview.findViewById(R.id.btnScan);
btnTest = (Button) rootview.findViewById(R.id.btnTest);
tvConnected = (TextView) rootview.findViewById(R.id.tvPrinterConnect);
KeyListenerInit();
return rootview;
}
public void setTvText(String text)
{
tvConnected = (TextView) getActivity().findViewById(R.id.tvPrinterConnect);
tvConnected.setText(text);
}
public void btnScanEnable(Boolean set)
{
btnScan = (Button)getActivity().findViewById(R.id.btnScan);
btnScan.setEnabled(set);
}
public void KeyListenerInit() {
btnScan.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent serverIntent = new Intent(getActivity(), DeviceListActivity.class);
startActivityForResult(serverIntent, REQUEST_CONNECT_DEVICE);
}
});
((MainActivity)getActivity()).setMService();
}
}
チェックフラグメントのコードが正しく。私はフラグメントonDestroyメソッドでサービスを切断すると思います。 –
いいえ私はこのコードのために@HiteshGehlot @HiteshGehlot –
の ''（（MainActivity）getActivity（））setMService（）; ''私はそれを正しい方法で呼び出すと思いますか？ @HiteshGehlot –