From 9b992b4800c4eedb9b7abf40b932839835519b19 Mon Sep 17 00:00:00 2001
From: Eugene Kuleshov <ekuleshov@gmail.com>
Date: Wed, 4 Dec 2024 22:11:48 -0500
Subject: [PATCH] force TRANSPORT_LE for connectGatt on Android 5 (#111)

---
 .../MyCentralManager.kt                       | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/bluetooth_low_energy_android/android/src/main/kotlin/dev/hebei/bluetooth_low_energy_android/MyCentralManager.kt b/bluetooth_low_energy_android/android/src/main/kotlin/dev/hebei/bluetooth_low_energy_android/MyCentralManager.kt
index 7afa156..6b750d3 100644
--- a/bluetooth_low_energy_android/android/src/main/kotlin/dev/hebei/bluetooth_low_energy_android/MyCentralManager.kt
+++ b/bluetooth_low_energy_android/android/src/main/kotlin/dev/hebei/bluetooth_low_energy_android/MyCentralManager.kt
@@ -26,6 +26,7 @@ import androidx.core.app.ActivityCompat
 import androidx.core.app.ActivityOptionsCompat
 import androidx.core.content.ContextCompat
 import io.flutter.plugin.common.BinaryMessenger
+import java.lang.reflect.Method
 import java.util.concurrent.Executor
 
 class MyCentralManager(context: Context, binaryMessenger: BinaryMessenger) : MyBluetoothLowEnergyManager(context), MyCentralManagerHostAPI {
@@ -174,7 +175,23 @@ class MyCentralManager(context: Context, binaryMessenger: BinaryMessenger) : MyB
                 val transport = BluetoothDevice.TRANSPORT_LE
                 device.connectGatt(context, autoConnect, mBluetoothGattCallback, transport)
             } else {
-                device.connectGatt(context, autoConnect, mBluetoothGattCallback)
+                try {
+                    // From Android LOLLIPOP (21) the transport types exists, but it is private
+                    // have to use reflection to call it for TRANSPORT_LE
+                    val connectGattMethod: Method = device.javaClass.getDeclaredMethod(
+                        "connectGatt",
+                        Context::class.java,
+                        Boolean::class.javaPrimitiveType,
+                        BluetoothGattCallback::class.java,
+                        Int::class.javaPrimitiveType
+                    )
+                    connectGattMethod.isAccessible = true
+                    connectGattMethod.invoke(
+                        device, context, autoConnect, mBluetoothGattCallback, 2 /* TRANSPORT_LE */) as BluetoothGatt
+                } catch (ex: Exception) {
+                    // fall back to default method if reflection fails
+                    device.connectGatt(context, autoConnect, mBluetoothGattCallback)
+                }
             }
             mConnectCallbacks[addressArgs] = callback
         } catch (e: Throwable) {