連線 API

如要判斷應用程式是否在 Android Auto 或 Android Automotive OS 上執行，請使用 CarConnection API 在執行階段擷取連線資訊。例如：

1. 在車用應用程式的 Session 中，初始化 CarConnection 並訂閱 LiveData 更新：

   Kotlin

   CarConnection(carContext).type.observe(this, ::onConnectionStateUpdated)
   

   Java

   new CarConnection(getCarContext()).getType().observe(this, this::onConnectionStateUpdated);
   

2. 在觀察器中，回應連線狀態的變更：

   Kotlin

   fun onConnectionStateUpdated(connectionState: Int) {
     val message = when(connectionState) {
       CarConnection.CONNECTION_TYPE_NOT_CONNECTED -> "Not connected to a head unit"
       CarConnection.CONNECTION_TYPE_NATIVE -> "Connected to Android Automotive OS"
       CarConnection.CONNECTION_TYPE_PROJECTION -> "Connected to Android Auto"
       else -> "Unknown car connection type"
     }
     CarToast.makeText(carContext, message, CarToast.LENGTH_SHORT).show()
   }
   

   Java

   private void onConnectionStateUpdated(int connectionState) {
     String message;
     switch(connectionState) {
       case CarConnection.CONNECTION_TYPE_NOT_CONNECTED:
         message = "Not connected to a head unit";
         break;
       case CarConnection.CONNECTION_TYPE_NATIVE:
         message = "Connected to Android Automotive OS";
         break;
       case CarConnection.CONNECTION_TYPE_PROJECTION:
         message = "Connected to Android Auto";
         break;
       default:
         message = "Unknown car connection type";
         break;
     }
     CarToast.makeText(getCarContext(), message, CarToast.LENGTH_SHORT).show();
   }