官方介绍的Bluetooth

https://developer.android.com/guide/topics/connectivity/bluetooth

使用Bluetooth APIs 可以做到：
Scan for other Bluetooth devices. 扫瞄蓝芽装置
Query the local Bluetooth adapter for paired Bluetooth devices. 查询并配对
Establish RFCOMM channels. 建立通讯
Connect to other devices through service discovery. 使用Service 采索进行连线
Transfer data to and from other devices. 传输档案
Manage multiple connections. 管理多装置

使用蓝芽连线主要有个步骤（基本要求工作)：
Setting up Bluetooth.
Finding devices that are either paired or available in the local area.
Connecting devices.
Transferring data between devices.

在android.bluetooth 提供的功能，有以下几个主要的类别：

• BluetoothAdapter
• BluetoothDevice
• BluetoothSocket
• BluetoothServerSocket
• BluetoothClass
• BluetoothProfile
• BluetoothHeadset
• BluetoothA2dp
• BluetoothHealth
• BluetoothHealthCallback
• BluetoothHealthAppConfiguration
• BluetoothProfile.ServiceListener

连线时，主要两个步骤：

1. Get the BluetoothAdapter
2. Enable Bluetooth
3. Get a BluetoothServerSocket by calling listenUsingRfcommWithServiceRecord().
4. Start listening for connection requests by calling accept().
5. Unless you want to accept additional connections, call close().