Update FlutterBluePlugin.java

android/build.gradle

@@ -9,7 +9,7 @@ buildscript {
 
     dependencies {
         classpath 'com.android.tools.build:gradle:3.5.2'
-        classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.7'
+        classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.13'
     }
 }
 

android/src/main/java/com/pauldemarco/flutterblue/FlutterBluePlugin.java

@@ -76,12 +76,12 @@ public class FlutterBluePlugin implements MethodCallHandler, RequestPermissionsR
     private BluetoothAdapter mBluetoothAdapter;
     private final Map<String, BluetoothGatt> mGattServers = new HashMap<>();
     private LogLevel logLevel = LogLevel.EMERGENCY;
-	private Result requestMtuCallback;
 
     // Pending call and result for startScan, in the case where permissions are needed
     private MethodCall pendingCall;
     private Result pendingResult;
     private BroadcastReceiver bondStateBroadcastReceiver = null;
+	Result resultMTU;
 
     /**
      * Plugin registration.
@@ -351,7 +351,7 @@ public void onReceive(Context context, Intent intent) {
 			     // this part is executed when an exception (in this example InterruptedException) occurs
 			}
 			//gattServer = device.connectGatt(registrar.activity(), false, mGattCallback);
-                    gattServer = device.connectGatt(registrar.activity(), options.getAndroidAutoConnect(), mGattCallback, BluetoothDevice.TRANSPORT_AUTO, BluetoothDevice.PHY_LE_CODED);
+                    gattServer = device.connectGatt(registrar.activity(), options.getAndroidAutoConnect(), mGattCallback, BluetoothDevice.TRANSPORT_LE);
                 } else {
 			 			 try 
 {
@@ -377,6 +377,7 @@ public void onReceive(Context context, Intent intent) {
                 if(gattServer != null) {
 		    gattServer.disconnect();
                     gattServer.close();
+		    gattServer = null;
                 }
                 result.success(null);
                 break;
@@ -427,9 +428,9 @@ public void onReceive(Context context, Intent intent) {
                 }
                 break;
             }
-
-            case "requestMtu": {
-
+			
+	  case "mtu":
+            {
                 Integer size = call.argument("size");
                 String remoteId = call.argument("remoteId");
                 if (size == null) {
@@ -446,14 +447,46 @@ public void onReceive(Context context, Intent intent) {
                     gattServer = mGattServers.get(remoteId);
                     if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
 
-			    boolean re = gattServer.requestMtu(size);
-			    Log.i(TAG, "New MTU status is " + re);
+			    boolean re = gattServer.requestMtu(2000);
+			    Log.i(TAG, "MTU status is " + re);
                         if(re) {
-				requestMtuCallback = result;
-                            //result.success(true);
+                            result.success(true);
                         } else {
-                            result.error("requestMtu", "gatt.requestMtu returned false", null);
+                            result.error("getMtu", "gatt.requestMtu returned false", null);
                         }
+                    } else {
+                        result.error("gettMtu", "Only supported on devices >= API 21 (Lollipop). This device == " + Build.VERSION.SDK_INT, null);
+                    }
+                } catch(Exception e) {
+                    result.error("getMtu", e.getMessage(), e);
+                }
+                break;
+            }
+
+
+
+            case "requestMtu": {
+
+                Integer size = call.argument("size");
+                String remoteId = call.argument("remoteId");
+                if (size == null) {
+                    result.error(
+                            "ValueError",
+                            "\"size\" cannot be null!",
+                            null
+                    );
+                    return;
+                }
+
+                BluetoothGatt gattServer;
+                try {
+                    gattServer = mGattServers.get(remoteId);
+                    if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+			  resultMTU = result;
+			   gattServer.requestMtu(size);
+
+
+
                     } else {
                         result.error("requestMtu", "Only supported on devices >= API 21 (Lollipop). This device == " + Build.VERSION.SDK_INT, null);
                     }
@@ -1134,29 +1167,33 @@ public void onMtuChanged(BluetoothGatt gatt, int mtu, int status) {
             log(LogLevel.DEBUG, "[onMtuChanged] mtu: " + mtu + " status: " + status);
 
 
-
-        if (status == BluetoothGatt.GATT_SUCCESS) {
-		    registrar.activity().runOnUiThread(
-                new Runnable() {
-                    @Override
-                    public void run() {
-                         			 try 
-{
-   requestMtuCallback.success(mtu);
-} 
-catch(InterruptedException e)
-{
-     // this part is executed when an exception (in this example InterruptedException) occurs
-}}});
-
-
-        } else {
-            requestMtuCallback.error("error", "gatt.requestMtu failed", null);
-        }
-        requestMtuCallback = null;
-
+                        if (status == BluetoothGatt.GATT_SUCCESS) {
+				registrar.activity().runOnUiThread(
+					new Runnable() {
+					    @Override
+					    public void run() {
+						    resultMTU.success(true);
+
+					    }
+					});
+                        } else {
+				registrar.activity().runOnUiThread(
+				new Runnable() {
+				    @Override
+				    public void run() {
+					    resultMTU.error("requestMtu", "gatt.requestMtu returned false", null);
+
+				    }
+				});
+
+
+                        }
+
 
-	    //...	
+
+
+
+
         }
     };
 

lib/src/bluetooth_device.dart

@@ -51,6 +51,13 @@ class BluetoothDevice {
     });
   }
 
+  Future<bool> getMtu(int size) async {
+    return await FlutterBlue.instance._channel.invokeMethod("mtu", {
+      "size": size,
+      "remoteId": id.toString(),
+    });
+  }
+
   Future<bool> bondDevice() async {
     return await FlutterBlue.instance._channel.invokeMethod("bondDevice", {
       "remoteId": id.toString(),