UUID

UUID(Universally Unique Identifier)：通用唯一识别码，软件建构的标准。其保证对同一时空中的所有机器都唯一。其目的是让分布式系统中的所有元素，都能有唯一的辨识资讯，而不需要透过中央控制端来做辨识资讯的指定。

蓝牙RFCOMM数据通信

一个蓝牙设备可提供多种服务，每种服务对应一个UUID。
服务有：蓝牙音频传输 A2DP，免提 HEADFREE，电话本 PBAP，串口通信 SPP。

可通过BluetoothSocket类建立有关蓝牙通信的套接字socket，通过MAC地址来识别远程设备，建立完通信连接RFCOMM通道后以输入、输出流方式通信。

public BluetoothSocket createRfcommSocketToServiceRecord(UUID uuid) 

其中的UUID参数指定socket的端口。

蓝牙通信分server服务器端和client客户端，它们用BluetoothSocket类的不同方法来获取数据。

server端：

 private class AcceptThread extends Thread { private final BluetoothServerSocket mmServerSocket; public AcceptThread() {             BluetoothServerSocket tmp = null; try {                 tmp = mAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID); } catch (IOException e) {                 e.printStackTrace(); }             mmServerSocket = tmp; } @Override public void run() { setName("AcceptThread");             BluetoothSocket socket = null; while (mState != STATE_CONNECTED) { try {                     socket = mmServerSocket.accept(); } catch (IOException e) {                     e.printStackTrace(); } if (socket != null) { synchronized (BluetoothChatService.this) { switch (mState) { case STATE_LISTEN: case STATE_CONNECTING: connected(socket, socket.getRemoteDevice()); break; case STATE_NONE: case STATE_CONNECTED: try {                                     socket.close(); } catch (IOException e) {                                     e.printStackTrace(); } break; } } } } } public void cancel() { try {                 mmServerSocket.close(); } catch (IOException e) {                 e.printStackTrace(); } } } 

client端：

 private class ConnectThread extends Thread { private final BluetoothSocket mmSocket; private final BluetoothDevice mmDevice; public ConnectThread(BluetoothDevice device) {             mmDevice = device;             BluetoothSocket tmp = null; try {                 tmp = device.createRfcommSocketToServiceRecord(MY_UUID); } catch (IOException e) {                 e.printStackTrace(); }             mmSocket = tmp; } @Override public void run() { setName("ConnectThread");             mAdapter.cancelDiscovery(); try {                 mmSocket.connect(); } catch (IOException e) { connectionFailed(); try {                     mmSocket.close(); } catch (IOException ex) {                     ex.printStackTrace(); }                 BluetoothChatService.this.start(); return; } synchronized (BluetoothChatService.this) {                 mConnectThread = null; } connected(mmSocket, mmDevice); } public void cancel() { try {                 mmSocket.close(); } catch (IOException e) {                 e.printStackTrace(); } } } private class ConnectedThread extends Thread { private final BluetoothSocket mmSocket; private final InputStream mmInStream; private final OutputStream mmOutStream; public ConnectedThread(BluetoothSocket socket) {             mmSocket = socket;             InputStream tmpIn = null;             OutputStream tmpOut = null; try {                 tmpIn = socket.getInputStream();                 tmpOut = socket.getOutputStream(); } catch (IOException e) {                 e.printStackTrace(); }             mmInStream = tmpIn;             mmOutStream = tmpOut; } @Override public void run() { byte[] buffer = new byte[1024]; int bytes; while (true) { try {                     bytes = mmInStream.read(buffer);                   mHandler.obtainMessage(homeFragment.MESSAGE_READ, bytes, -1, buffer).sendToTarget(); } catch (IOException e) { connectionLost(); break; } } } public void write(byte[] buffer) { try {                 mmOutStream.write(buffer);                 mHandler.obtainMessage(homeFragment.MESSAGE_WRITE, -1, -1, buffer).sendToTarget(); } catch (IOException e) {                 e.printStackTrace(); } } public void cancel() { try {                 mmSocket.close(); } catch (IOException e) {                 e.printStackTrace(); } } } 

synchronized：同步方法实现排队调用。

蓝牙相关权限

AndroidManifest.xml中添加：

<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" /> <uses-permission android:name="android.permission.BLUETOOTH" /> 

在Fragment中添加请求权限操作。

布局

Toolbar Menu

我使用的Android Studio的版本是3.5.3，对于toolbar还是直接使用AS自带的比较好。若是写出v7版本的toolbar，则会出现一些版本不支持的问题。

Toolbar：点击如图右上角图标显示下拉列表，下拉列表为option_menu.xml布局。

option_menu.xml:

<?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="https://schemas.android.com/apk/res/android"> <item android:id="@+id/scan"         android:icon="@android:drawable/ic_menu_myplaces"         android:title="@string/connect" /> <item android:id="@+id/discoverable"         android:icon="@android:drawable/ic_menu_view"         android:title="@string/discoverable" /> <item android:id="@+id/back"         android:icon="@android:drawable/ic_menu_close_clear_cancel"         android:title="@string/back" /> </menu> 

在Fragment中使用Toolbar和在Activity使用Toolbar有所不同。toolbar可作为独立控件， 在Fragment中无需加上
((AppCompatActivity) getActivity()).setSupportActionBar(toolbar);，
但需要加上setHasOptionsMenu(true) ，表示有menu待使用。

一开始这里没写正确，应用根本打不开，只有闪退。

homeFragment.java:

 Toolbar toolbar = (Toolbar) view.findViewById(R.id.toolbar); setHasOptionsMenu(true); // ((AppCompatActivity) getActivity()).setSupportActionBar(toolbar);  toolbar.inflateMenu(R.menu.option_menu); 

TextView ArrayAdapter

发送消息和蓝牙设备搜索显示这两部分有用到了ArrayAdapter，如：

mPairedDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.device_name); 

这种ArrayAdapter的定义使用到layout，其布局的根节点必须为TextView（如下代码），否则报错：ArrayAdapter requires the resource ID to be a TextView。

<?xml version="1.0" encoding="utf-8"?> <TextView xmlns:android="https://schemas.android.com/apk/res/android"     android:layout_width="match_parent"     android:layout_height="wrap_content"     android:textSize="18sp"> </TextView> 

蓝牙搜索链接

在点击了option_menu.xml中的“我的好友”之后，随后打开新的界面进行查看已链接过的设备和搜索发现的设备。以广播Broadcast的形式来实现接收扫描到的蓝牙设备。

DeviceList.java

 private final BroadcastReceiver mReceiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) {             String action = intent.getAction(); if (BluetoothDevice.ACTION_FOUND.equals(action)) {                 BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE); if (device.getBondState() != BluetoothDevice.BOND_BONDED) {                     mNewDevicesArrayAdapter.add(device.getName() + "n" + device.getAddress()); } } else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) { if (mNewDevicesArrayAdapter.getCount() == 0) {                     String noDevices = getResources().getText(R.string.none_found).toString();                     mNewDevicesArrayAdapter.add(noDevices); } } } }; private void init() {         Button scanButton = findViewById(R.id.button_scan);         scanButton.setOnClickListener(new View.OnClickListener() { public void onClick(View v) {                 Toast.makeText(DeviceList.this, R.string.scanning, Toast.LENGTH_LONG).show(); doDiscovery(); //搜索蓝牙设备 } });         mPairedDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.device_name);         mNewDevicesArrayAdapter = new ArrayAdapter<String>(this, R.layout.device_name); //已配对蓝牙设备列表         ListView pairedListView = findViewById(R.id.paired_devices);         pairedListView.setAdapter(mPairedDevicesArrayAdapter);         pairedListView.setOnItemClickListener(mPaireDeviceClickListener); //未配对蓝牙设备列表         ListView newDevicesListView = findViewById(R.id.new_devices);         newDevicesListView.setAdapter(mNewDevicesArrayAdapter);         newDevicesListView.setOnItemClickListener(mNewDeviceClickListener); //动态注册广播接收者         IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND); registerReceiver(mReceiver, filter);         filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED); registerReceiver(mReceiver, filter);         mBtAdapter = BluetoothAdapter.getDefaultAdapter();         Set<BluetoothDevice> pairedDevices = mBtAdapter.getBondedDevices(); if (pairedDevices.size() > 0) { findViewById(R.id.title_paired_devices).setVisibility(View.VISIBLE); for (BluetoothDevice device : pairedDevices) {                 mPairedDevicesArrayAdapter.add(device.getName() + "n" + device.getAddress()); } } else {             String noDevices = getResources().getText(R.string.none_paired).toString();             mPairedDevicesArrayAdapter.add(noDevices); } } 

Hander传递消息

使用Hander对象实现主线程与子线程之间传递消息，同时在“微信”tab界面显示当前链接状态。
homeFragment.java：

 mChatService = new BluetoothChatService(view.getContext(), mHandler); private final Handler mHandler = new Handler() { //消息处理 @Override public void handleMessage(Message msg) { switch (msg.what) { case MESSAGE_STATE_CHANGE: switch (msg.arg1) { case BluetoothChatService.STATE_CONNECTED:                             mTitle.setText(R.string.title_connected_to);                             mTitle.append(mConnectedDeviceName);                             mConversationArrayAdapter.clear(); break; case BluetoothChatService.STATE_CONNECTING:                             mTitle.setText(R.string.title_connecting); break; case BluetoothChatService.STATE_LISTEN: case BluetoothChatService.STATE_NONE:                             mTitle.setText(R.string.title_not_connected); break; } break; case MESSAGE_WRITE: byte[] writeBuf = (byte[]) msg.obj;                     String writeMessage = new String(writeBuf);                     mConversationArrayAdapter.add("我:  " + writeMessage); break; case MESSAGE_READ: byte[] readBuf = (byte[]) msg.obj;                     String readMessage = new String(readBuf, 0, msg.arg1);                     mConversationArrayAdapter.add(mConnectedDeviceName + ":  " + readMessage); break; case MESSAGE_DEVICE_NAME:                     mConnectedDeviceName = msg.getData().getString(DEVICE_NAME);                     Toast.makeText(getActivity().getApplicationContext(),"链接到 " + mConnectedDeviceName, Toast.LENGTH_SHORT).show(); break; case MESSAGE_TOAST:                     Toast.makeText(getActivity().getApplicationContext(), msg.getData().getString(TOAST), Toast.LENGTH_SHORT).show(); break; } } }; 

参阅：

• 对Android蓝牙UUID的理解
• 关于蓝牙通信文档 Android建立蓝牙RFCOMM通信
• fragment中toolbar的一些坑
• ArrayAdapter requires the resource ID to be a TextView问题
• 掌握手机Bluetooth的使用和Android对Bluetooth的支持
• Android Developers | Bluetooth

源码已上传至 GitHub。