feat: check connection status

android/src/main/java/id/kalanusa/flutter_zsdk/FlutterZsdkPlugin.java

 import java.util.Objects;
 
 import id.kalanusa.flutter_zsdk.bluetoothconnectionhandler.BluetoothConnectionHandler;
+import id.kalanusa.flutter_zsdk.bluetoothconnectionhandler.BluetoothConnectionHolder;
 import id.kalanusa.flutter_zsdk.bluetoothdiscoveryhandler.BluetoothDiscoveryHandler;
 import id.kalanusa.flutter_zsdk.bluetoothdiscoveryhandler.BluetoothPrinter;
 import io.flutter.Log;
 import io.flutter.plugin.common.PluginRegistry;
 
 /** FlutterZsdkPlugin */
-public class FlutterZsdkPlugin implements FlutterPlugin, MethodCallHandler, ActivityAware, PluginRegistry.RequestPermissionsResultListener {
+public class FlutterZsdkPlugin implements FlutterPlugin, MethodCallHandler, ActivityAware {
   /// The MethodChannel that will the communication between Flutter and native Android
   ///
   /// This local reference serves to register the plugin with the Flutter Engine and unregister it
   private DartExecutor dartExecutor;
   private BinaryMessenger binaryMessenger;
 
+  public BluetoothConnectionHolder bluetoothConnectionHolder;
+
+  public BluetoothConnectionHandler bluetoothConnectionHandler;
+
+
   @Override
   public void onAttachedToEngine(@NonNull FlutterPluginBinding flutterPluginBinding) {
     channel = new MethodChannel(flutterPluginBinding.getBinaryMessenger(), "flutter_zsdk");
   @Override
   public void onAttachedToActivity(@NonNull ActivityPluginBinding binding) {
     activity = binding.getActivity();
-    binding.addRequestPermissionsResultListener(this);
 
     new EventChannel(binaryMessenger, bluetoothDiscoveryEventChannel).setStreamHandler(new BluetoothDiscoveryHandler(context, activity));
   }
 
     switch(call.method) {
       case "bluetoothOpenConnection":
-        new BluetoothConnectionHandler(call.argument("macAddress")).handle(call, result);
-    }
-//    switch(call.method) {
-//      case "findBluetoothPrinters":
-//        findBluetoothPrinters();
-//      case "getPlatformVersion":
-//        Log.w("from native", "TEST");
-//      case "mengege":
-//        new BluetoothConnectionHandler(call.argument("macAddress"));
-//    }
-  }
-
-  @Override
-  public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
-    channel.setMethodCallHandler(null);
-  }
-
-  @Override
-  public boolean onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
-    if (requestCode == 1001) { // Check if it'sthe request we initiated
-      if (grantResults.length > 0) {
-        boolean bluetoothScanGranted = grantResults[0] == PackageManager.PERMISSION_GRANTED;
-        boolean bluetoothConnectGranted = grantResults[1] == PackageManager.PERMISSION_GRANTED;
-        boolean locationGranted = grantResults[2] == PackageManager.PERMISSION_GRANTED;
-
-        if (bluetoothScanGranted && bluetoothConnectGranted && locationGranted) {
-          // All permissions granted, proceed with Bluetooth operations
-          // ... your Bluetooth code here ...
-          this.startDiscoverBluetoothPrinters();
-        } else {
-          System.out.println("Permission Denied, please allow permission to discover bluetooth devices");
-          // Handle denied permissions
-          // You might display a messageto the user or disable Bluetooth features
-          // ... your logic for handling denied permissions ...
+      case "isConnected":
+        if (bluetoothConnectionHandler == null) {
+          bluetoothConnectionHandler = new BluetoothConnectionHandler(bluetoothConnectionHolder);
         }
-      }
-    }
-
-    return true;
-  }
 
+        bluetoothConnectionHandler.handle(call, result);
+        break;
 
-//  Bluetooth discovery
-  public void findBluetoothPrinters() {
-    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
-      if (context.checkSelfPermission(Manifest.permission.BLUETOOTH_SCAN) != PackageManager.PERMISSION_GRANTED ||
-              context.checkSelfPermission(Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED ||
-              context.checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
-
-        activity.requestPermissions(new String[]{
-                Manifest.permission.BLUETOOTH_SCAN,
-                Manifest.permission.BLUETOOTH_CONNECT,
-                Manifest.permission.ACCESS_FINE_LOCATION
-        }, 1001);
-      } else {
-        this.startDiscoverBluetoothPrinters();
-      }
-    } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
-      if (context.checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
-        activity.requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 1002);
-      } else {
-        this.startDiscoverBluetoothPrinters();
-      }
     }
   }
 
-  public void startDiscoverBluetoothPrinters() {
-    new EventChannel(dartExecutor, bluetoothDiscoveryEventChannel).setStreamHandler(
-            new EventChannel.StreamHandler() {
-
-              @Override
-              public void onListen(Object arguments, EventChannel.EventSink events) {
-                Log.w("From native", "Adding Listener");
-                attachEvent = events;
-                handler = new Handler();
-                startDiscoverBluetoothPrintersRunnable.run();
-              }
-
-              @Override
-              public void onCancel(Object arguments) {
-                Log.w("From native", "Cancelling Listener");
-                handler.removeCallbacks(startDiscoverBluetoothPrintersRunnable);
-                handler = null;
-                attachEvent = null;
-                System.out.println("StreamHandler - onCanceled: ");              }
-            }
-    );
+  @Override
+  public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
+    channel.setMethodCallHandler(null);
   }
-
-//  public void startDiscoverBluetoothPrintersRunnable() {
-//    new Thread(new Runnable() {
-//      @Override
-//      public void run() {
-//
-//    });
-//  }
-//
-  private final Runnable startDiscoverBluetoothPrintersRunnable = new Runnable() {
-    @Override
-    public void run() {
-      ArrayList<BluetoothPrinter> tempDiscoveredPrinterList = new ArrayList<BluetoothPrinter>();
-      DiscoveryHandler discoveryHandler = new DiscoveryHandler() {
-        @Override
-        public void foundPrinter(DiscoveredPrinter discoveredPrinter) {
-          Map<String, String> discoveredPrinterDataMap = discoveredPrinter.getDiscoveryDataMap();
-          System.out.println("Found printer "  + discoveredPrinterDataMap.get("FRIENDLY_NAME"));
-
-          BluetoothPrinter bluetoothPrinter = new BluetoothPrinter(discoveredPrinterDataMap.get("FRIENDLY_NAME"), discoveredPrinterDataMap.get("MAC_ADDRESS"));
-          tempDiscoveredPrinterList.add(bluetoothPrinter);
-          attachEvent.success(tempDiscoveredPrinterList);
-        }
-
-        @Override
-        public void discoveryFinished() {
-          // return value here, this is asynchronous
-          Log.w("From Native", "Discovery Success, found "+ tempDiscoveredPrinterList.size() + " Printer(s)");
-          attachEvent.endOfStream();
-        }
-
-        @Override
-        public void discoveryError(String s) {
-          System.out.println("Error when discovering bluetooth device");
-          System.out.println("message:" + s);
-        }
-      };
-
-      try {
-        BluetoothDiscoverer.findPrinters(context, discoveryHandler);
-      } catch (ConnectionException e) {
-        System.out.println("Error when finding printers");
-//            throw new RuntimeException(e);
-      }
-    }
-  };
 }

android/src/main/java/id/kalanusa/flutter_zsdk/bluetoothconnectionhandler/BluetoothConnectionHandler.java

 import io.flutter.plugin.common.MethodChannel;
 
 public class BluetoothConnectionHandler {
-    Connection connection;
+    BluetoothConnectionHolder bluetoothConnectionHolder;
     String macAddress;
 
-    public BluetoothConnectionHandler(String macAddress) {
-        this.macAddress = macAddress;
-        connection = new BluetoothConnectionInsecure(macAddress);
+    public BluetoothConnectionHandler(BluetoothConnectionHolder bluetoothConnectionHolder) {
+        this.bluetoothConnectionHolder = bluetoothConnectionHolder;
     }
 
     public void handle(@NonNull MethodCall call, @NonNull MethodChannel.Result result) {
-        Log.w("From Native (Android)", "ini di BluetoothConnectionHandler");
-        Log.w("From Native (Android)", macAddress);
 
-        connection = new BluetoothConnectionInsecure(macAddress);
+        switch (call.method) {
+            case "bluetoothOpenConnection":
+                if (bluetoothConnectionHolder == null) {
+                    bluetoothConnectionHolder = new BluetoothConnectionHolder(new BluetoothConnectionInsecure(call.argument("macAddress")));
+                }
+
+                openConnection(result);
+                break;
 
-        openConnection(result);
+            case "isConnected":
+                checkConnection(result);
+                break;
+        }
     }
 
     public void openConnection(@NonNull MethodChannel.Result result) {
             public void run() {
                 try {
                     Looper.prepare();
-                    connection.open();
+                    bluetoothConnectionHolder.connection.open();
                     Looper.myLooper().quit();
                     result.success(null);
                     Log.w("From Native (Android)", "open connection finished");
         }).start();
     }
 
+    public void checkConnection(@NonNull MethodChannel.Result result) {
+        new Thread(new Runnable() {
+            @Override
+            public void run() {
+                boolean isConnected = bluetoothConnectionHolder.connection.isConnected();
+
+                result.success(isConnected);
+
+                Log.w("From Native (Android)", "isConnected: " + isConnected);
+            }
+        }).start();
+    }
+
 
 }

android/src/main/java/id/kalanusa/flutter_zsdk/bluetoothconnectionhandler/BluetoothConnectionHolder.java

+package id.kalanusa.flutter_zsdk.bluetoothconnectionhandler;
+
+import androidx.annotation.NonNull;
+
+import com.zebra.sdk.comm.Connection;
+
+public class BluetoothConnectionHolder {
+    public Connection connection;
+
+    public BluetoothConnectionHolder(@NonNull Connection connection) {
+        this.connection = connection;
+    }
+
+    public void updateConnection(@NonNull Connection connection) {
+        this.connection = connection;
+    }
+}

example/lib/main.dart

               onPressed: _selectedBluetoothPrinterMacAddress == null || _connectedPrinter != null ? null : openConnection,
             ),
             SizedBox(height: 20),
+
+            ElevatedButton(
+              child: Text('Check connection status'),
+              onPressed: () async {
+                bool isConnected =await _flutterZsdkPlugin.isConnected();
+              
+                print('isConnected from dart: $isConnected');
+              },
+            ),
+            SizedBox(height: 20),
             
             ElevatedButton(
               child: Text(_isDiscovering ? 'Discovering bluetooth printers...' : 'Discover nearby bluetooth printers'),

lib/flutter_zsdk.dart

   Future<void> openConnection(String macAddress) {
     return FlutterZsdkPlatform.instance.openConnection(macAddress);
   }
+
+  /// this api must not be called before FlutterZsdkPlugin.openConnection()
+  Future<bool> isConnected() {
+    return FlutterZsdkPlatform.instance.isConnected();
+  }
 }

lib/src/flutter_zsdk_method_channel.dart

       throw FlutterZsdkException("Failed to open connection to printer: $e");
     }
   }
+
+  @override
+  Future<bool> isConnected() async {
+    bool isConnected = await methodChannel.invokeMethod('isConnected');
+
+    return isConnected;
+  }
 }

lib/src/flutter_zsdk_platform_interface.dart

   Future<void> openConnection(String macAddress) {
     throw UnimplementedError('openConnection() has not been implemented.');
   }
+
+  Future<bool> isConnected() {
+    throw UnimplementedError('isConnected() has not been implemented.');
+  }
 }