Android蓝牙操作笔记（转）

2023-07-22 16:00:10

蓝牙是一种支持设备短距离传输数据的无线技术。android在2.0以后提供了这方面的支持。
从查找蓝牙设备到能够相互通信要经过几个基本步骤(本机做为服务器)：
1.设置权限
在manifest中配置

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

2.启动蓝牙
首先要查看本机是否支持蓝牙，获取BluetoothAdapter蓝牙适配器对象

BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if(mBluetoothAdapter == null){
//表明此手机不支持蓝牙
return;
}
if(!mBluetoothAdapter.isEnabled()){ //蓝牙未开启，则开启蓝牙
Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
}
//......
public void onActivityResult(int requestCode, int resultCode, Intent data){
if(requestCode == REQUEST_ENABLE_BT){
if(requestCode == RESULT_OK){
//蓝牙已经开启
}
}
}

3。发现蓝牙设备
这里可以细分为几个方面
(1)使本机蓝牙处于可见(即处于易被搜索到状态)，便于其他设备发现本机蓝牙

//使本机蓝牙在300秒内可被搜索
private void ensureDiscoverable() {
if (mBluetoothAdapter.getScanMode() !=
BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
startActivity(discoverableIntent);
}
}

(2)查找已经配对的蓝牙设备，即以前已经配对过的设备

Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
if (pairedDevices.size() > 0) {
findViewById(R.id.title_paired_devices).setVisibility(View.VISIBLE);
for (BluetoothDevice device : pairedDevices) {
//device.getName() +" "+ device.getAddress());
}
} else {
mPairedDevicesArrayAdapter.add("没有找到已匹对的设备");
}

(3)通过mBluetoothAdapter.startDiscovery();搜索设备，要获得此搜索的结果需要注册
一个BroadcastReceiver来获取。先注册再获取信息，然后处理

//注册，当一个设备被发现时调用onReceive
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
this.registerReceiver(mReceiver, filter);
//当搜索结束后调用onReceive
filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
this.registerReceiver(mReceiver, filter);
//.......
private 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);
// 已经配对的则跳过
if (device.getBondState() != BluetoothDevice.BOND_BONDED) {
mNewDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress()); //保存设备地址与名字
}
}else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) { //搜索结束
if (mNewDevicesArrayAdapter.getCount() == 0) {
mNewDevicesArrayAdapter.add("没有搜索到设备");
}
}
}
};

4.建立连接
查找到设备后，则需要建立本机与其他设备之间的连接。
一般用本机搜索其他蓝牙设备时，本机可以作为一个服务端，接收其他设备的连接。
启动一个服务器端的线程，死循环等待客户端的连接，这与ServerSocket极为相似。
这个线程在准备连接之前启动

//UUID可以看做一个端口号
private static final UUID MY_UUID =
UUID.fromString("fa87c0d0-afac-11de-8a39-0800200c9a66");
//像一个服务器一样时刻监听是否有连接建立
private class AcceptThread extends Thread{
private BluetoothServerSocket serverSocket;
public AcceptThread(boolean secure){
BluetoothServerSocket temp = null;
try {
temp = mBluetoothAdapter.listenUsingRfcommWithServiceRecord(
NAME_INSECURE, MY_UUID);
} catch (IOException e) {
Log.e("app", "listen() failed", e);
}
serverSocket = temp;
}
public void run(){
BluetoothSocket socket=null;
while(true){
try {
socket = serverSocket.accept();
} catch (IOException e) {
Log.e("app", "accept() failed", e);
break;
}
}
if(socket!=null){
//此时可以新建一个数据交换线程，把此socket传进去
}
}
//取消监听
public void cancel(){
try {
serverSocket.close();
} catch (IOException e) {
Log.e("app", "Socket Type" + socketType + "close() of server failed", e);
}
}
}

搜索到设备后可以获取设备的地址，通过此地址获取一个BluetoothDeviced对象，可以看做客户端，通过此对象device.createRfcommSocketToServiceRecord(MY_UUID);同一个UUID可与服务器建立连接获取另一个socket对象，由此服务端与客户端各有一个socket对象，此时
他们可以互相交换数据了。
创立客户端socket可建立线程

//另一个设备去连接本机,相当于客户端
private class ConnectThread extends Thread{
private BluetoothSocket socket;
private BluetoothDevice device;
public ConnectThread(BluetoothDevice device,boolean secure){
this.device = device;
BluetoothSocket tmp = null;
try {
tmp = device.createRfcommSocketToServiceRecord(MY_UUID_SECURE);
} catch (IOException e) {
Log.e("app", "create() failed", e);
}
}
public void run(){
mBluetoothAdapter.cancelDiscovery(); //取消设备查找
try {
socket.connect();
} catch (IOException e) {
try {
socket.close();
} catch (IOException e1) {
Log.e("app", "unable to close() "+
" socket during connection failure", e1);
}
connetionFailed(); //连接失败
return;
}
//此时可以新建一个数据交换线程，把此socket传进去
}
public void cancel() {
try {
socket.close();
} catch (IOException e) {
Log.e("app", "close() of connect socket failed", e);
}
}
}

5.建立数据通信线程，进行读取数据

//建立连接后，进行数据通信的线程
private class ConnectedThread extends Thread{
private BluetoothSocket socket;
private InputStream inStream;
private OutputStream outStream;
public ConnectedThread(BluetoothSocket socket){
this.socket = socket;
try {
//获得输入输出流
inStream = socket.getInputStream();
outStream = socket.getOutputStream();
} catch (IOException e) {
Log.e("app", "temp sockets not created", e);
}
}
public void run(){
byte[] buff = new byte[1024];
int len=0;
//读数据需不断监听，写不需要
while(true){
try {
len = inStream.read(buff);
//把读取到的数据发送给UI进行显示
Message msg = handler.obtainMessage(BluetoothChat.MESSAGE_READ,
len, -1, buff);
msg.sendToTarget();
} catch (IOException e) {
Log.e("app", "disconnected", e);
connectionLost(); //失去连接
start(); //重新启动服务器
break;
}
}
}
public void write(byte[] buffer) {
try {
outStream.write(buffer);
// Share the sent message back to the UI Activity
handler.obtainMessage(BluetoothChat.MESSAGE_WRITE, -1, -1, buffer)
.sendToTarget();
} catch (IOException e) {
Log.e("app", "Exception during write", e);
}
}
public void cancel() {
try {
socket.close();
} catch (IOException e) {
Log.e("app", "close() of connect socket failed", e);
}
}
}

到这里，蓝牙通信的基本操作已经全部完成。

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