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蓝牙开发基础知识

news 文章来源：https://blog.csdn.net/jx0260/article/details/127224035 2025/4/18 22:34:47

零、基础知识

0.1、Android 应用可通过 Bluetooth API 执行以下操作

扫描其他蓝牙设备
查询本地蓝牙适配器的配对蓝牙设备
建立 RFCOMM 通道
通过服务发现连接到其他设备
与其他设备进行双向数据传输
管理多个连接

0.2、蓝牙进行通信的四大必需任务

设置蓝牙
查找局部区域内的配对设备或可用设备
连接设备
在设备之间传输数据

0.3、动作

请求连接、接受连接和传输数据

蓝牙协议是适用于设备间蓝牙通信的无线接口规范。
如果手机要与无线耳机进行连接，则两台设备都必须支持免提蓝牙协议。

0.4、协议

HFP协议：Android 提供 BluetoothHeadset 类，该类是用于控制蓝牙耳机服务的代理。其中包括蓝牙耳机和免提 (v1.5) 的协议。BluetoothHeadset 类包含对 AT 命令的支持。
A2DP协议：定义如何通过蓝牙连接和流式传输，将高质量音频从一个设备传输至另一个设备。Android 提供 BluetoothA2dp 类，该类是用于控制蓝牙 A2DP 服务的代理。
蓝牙健康设备 (HDP)协议：该协议允许您创建应用，从而与支持蓝牙功能的健康设备（例如心率监测仪、血糖仪、温度计、台秤等）进行通信。

0.5、名词

RFCOMM 通道
AT 命令
耳机协议
BluetoothHeadset类
BluetoothSocket类
SDP lookup of uuid
SDP record

供应商特定的 AT 命令
从 Android 3.0（API 级别 11）开始，应用可注册接收耳机发送的预定义供应商特定 AT 命令（例如 Plantronics +XEVENT 命令）的系统广播。例如，应用可接收指示所连接设备电池电量的广播，并根据需要通知用户或采取其他操作。为 ACTION_VENDOR_SPECIFIC_HEADSET_EVENT Intent 创建广播接收器，以处理耳机的供应商特定 AT 命令。

一、使用蓝牙

1.1 设置蓝牙

启用蓝牙：
获取 BluetoothAdapter。
所有蓝牙 Activity 都需要 BluetoothAdapter。如要获取 BluetoothAdapter，请调用静态的 getDefaultAdapter() 方法。此方法会返回一个 BluetoothAdapter 对象，表示设备自身的蓝牙适配器（蓝牙无线装置）。整个系统只有一个蓝牙适配器，并且您的应用可使用此对象与之进行交互。如果 getDefaultAdapter() 返回 null，则表示设备不支持蓝牙。

BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (bluetoothAdapter == null) {// Device doesn't support Bluetooth
} else {if (!bluetoothAdapter.isEnabled()) {Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);}
}

如果成功启用蓝牙，您的 Activity 会在 onActivityResult() 回调中收到 RESULT_OK 结果代码。如果由于某个错误（或用户响应“No”）未成功启用蓝牙，则结果代码为 RESULT_CANCELED。

1.2 查找设备

1.2.1 设备发现

如要开始发现设备，只需调用 startDiscovery()。该进程为异步操作，并且会返回一个布尔值，指示发现进程是否已成功启动。发现进程通常包含约 12 秒钟的查询扫描，随后会对发现的每台设备进行页面扫描，以检索其蓝牙名称。

@Override
protected void onCreate(Bundle savedInstanceState) {...// Register for broadcasts when a device is discovered.IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);registerReceiver(receiver, filter);
}// Create a BroadcastReceiver for ACTION_FOUND.
private final BroadcastReceiver receiver = new BroadcastReceiver() {public void onReceive(Context context, Intent intent) {String action = intent.getAction();if (BluetoothDevice.ACTION_FOUND.equals(action)) {// Discovery has found a device. Get the BluetoothDevice// object and its info from the Intent.BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);String deviceName = device.getName();String deviceHardwareAddress = device.getAddress(); // MAC address}}
};@Override
protected void onDestroy() {super.onDestroy();...// Don't forget to unregister the ACTION_FOUND receiver.unregisterReceiver(receiver);
}

1.2.2 查询配对设备的列表

Set<BluetoothDevice> pairedDevices = bluetoothAdapter.getBondedDevices();if (pairedDevices.size() > 0) {// There are paired devices. Get the name and address of each paired device.for (BluetoothDevice device : pairedDevices) {String deviceName = device.getName();String deviceHardwareAddress = device.getAddress(); // MAC address}
}

1.2.3 启用可检测性

Intent discoverableIntent =new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300); // 可检测性开启300秒
startActivity(discoverableIntent);

注意：如果尚未在设备上启用蓝牙，则启用设备可检测性会自动启用蓝牙。

1.2.4 已配对与已连接的区别

已配对是指两台设备知晓彼此的存在，具有可用于身份验证的共享链路密钥，并且能够与彼此建立加密连接。
已连接是指设备当前共享一个 RFCOMM 通道，并且能够向彼此传输数据。当前的 Android Bluetooth API 要求规定，只有先对设备进行配对，然后才能建立 RFCOMM 连接。在使用 Bluetooth API 发起加密连接时，系统会自动执行配对。

二、连接设备

2.1. 连接技术

2.1.1 作为服务器连接

private class AcceptThread extends Thread {private final BluetoothServerSocket mmServerSocket;public AcceptThread() {// Use a temporary object that is later assigned to mmServerSocket// because mmServerSocket is final.BluetoothServerSocket tmp = null;try {// MY_UUID is the app's UUID string, also used by the client code.tmp = bluetoothAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID);} catch (IOException e) {Log.e(TAG, "Socket's listen() method failed", e);}mmServerSocket = tmp;}public void run() {BluetoothSocket socket = null;// Keep listening until exception occurs or a socket is returned.while (true) {try {socket = mmServerSocket.accept();} catch (IOException e) {Log.e(TAG, "Socket's accept() method failed", e);break;}if (socket != null) {// A connection was accepted. Perform work associated with// the connection in a separate thread.manageMyConnectedSocket(socket);mmServerSocket.close();break;}}}// Closes the connect socket and causes the thread to finish.public void cancel() {try {mmServerSocket.close();} catch (IOException e) {Log.e(TAG, "Could not close the connect socket", e);}}
}

2.1.2 作为客户端连接

private class ConnectThread extends Thread {private final BluetoothSocket mmSocket;private final BluetoothDevice mmDevice;public ConnectThread(BluetoothDevice device) {// Use a temporary object that is later assigned to mmSocket// because mmSocket is final.BluetoothSocket tmp = null;mmDevice = device;try {// Get a BluetoothSocket to connect with the given BluetoothDevice.// MY_UUID is the app's UUID string, also used in the server code.tmp = device.createRfcommSocketToServiceRecord(MY_UUID);} catch (IOException e) {Log.e(TAG, "Socket's create() method failed", e);}mmSocket = tmp;}public void run() {// Cancel discovery because it otherwise slows down the connection.bluetoothAdapter.cancelDiscovery();try {// Connect to the remote device through the socket. This call blocks// until it succeeds or throws an exception.mmSocket.connect();} catch (IOException connectException) {// Unable to connect; close the socket and return.try {mmSocket.close();} catch (IOException closeException) {Log.e(TAG, "Could not close the client socket", closeException);}return;}// The connection attempt succeeded. Perform work associated with// the connection in a separate thread.manageMyConnectedSocket(mmSocket);}// Closes the client socket and causes the thread to finish.public void cancel() {try {mmSocket.close();} catch (IOException e) {Log.e(TAG, "Could not close the client socket", e);}}
}