Android蓝牙应用程序开发的基本步骤
在Android系统中，开发蓝牙应用程序的基本步骤如下：
1.设置权限
在文件AndroidManifest.xml中声明使用蓝牙的权限，代码如下：
2.启动蓝牙
BluetoothAdapter mBuletoothAdapter = BuletoothAdapter.getDefaultAdapter();
if(mBuletoothAdapter == 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
(1)首先使本机蓝牙处于可见状态（即处于易被搜索到的状态），便于其他设备发现本机蓝牙，演示代码如下：
//使本机蓝牙在300秒内可被搜索
private void ensureDiscoverable() {
if(mBuletoothAdapter.getScanMode() != BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DRATION, 300);
startActivity(discoverableIntent);
}
}
(2)然后查找已经配对的蓝牙设备，即以前已经配对过的设备，演示代码如下：
Set 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 {
mPairedDeviceArrayAdapter.add("没有找到已配对的设备");
}
(3)最后通过 mBluetoothAdapter.startDiscovery() 方法来搜索设备，在此需要注册一个 BroadcastReceiver 来获得这个搜索结果。即先注册再获取信息，然后进行处理。演示代码如下：
//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);
//已经配对过的则跳过
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
当查找到蓝牙设备后，接下来需要建立本机与其他设备之间的连接。一般在使用本机搜索其他蓝牙设备时，本机可以作为一个服务端来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，此线程在准备连接之前启动。演示代码如下：
//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建立连接
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", "Scoket Type", + socketType + "close() of server failed", e);
}
}
}
5.交换数据
当搜索到蓝牙设备后，接下来可以获取设备的地址，通过此地址获取一个BluetoothDevice对象，可以将其看做一个客户端，通过对象device.createRfcommSocketTo ServiceRecord(MY_UUID)同一个UUID可与服务器建立连接获取另一个socket对象。因为此服务端与客户端各有一个socket对象，所以此时它们可以相互交换数据，演示代码如下：
//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);
}
connectionFailed(); //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);
}
}
}
6.建立数据通信线程
这一阶段的任务是读取通信数据，演示代码如下：
//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;
//读数据需要不断监听，写数据不需要
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);
handler.obtainMessage(BluetoothChat.MESSAGE_WRITE, -1, -1, buffer).sendToTarget();
}
catch (IOException e)
{
Log.e("app", "Exception during write", e);
}
}
public void cancle() {
try{
socket.close();
}
catch (IOException e){
Log.e("app", "close() of connect socket failed", e);
}
}
}