蓝牙采用分散式网络结构以及快调频和短包技术,支持点对点及点对多点通信,工作在全球通用的2.4GHz ISM(I-工业、S-科学、M-医学)频段,其数据速率为1Mbps,采用时分双工传输方案。
蓝牙协议可分4层:
1. 核心协议层
2. 电缆替代协议层
3. 电话控制协议层
4. 其他协议层
蓝牙协议之核心协议层包括
1. 基带,
2. 链路管理, LMP, 负责蓝牙组件间连接的建立,
3. 逻辑链路控制和适应协议, L2CAP,
4. 业务搜寻协议, SDP, 通过SDP可以查询设备信息、业务及业务特征、并在查询之后建立两个或多个蓝牙设备间的连接。SDP支持3种查询方式:按业务类别搜索,按业务熟悉搜索,业务浏览。
蓝牙是android 2.0的包,在建立android工程时,一定要将API Level等级设置为5,即android 2.0。
蓝牙api位于android.bluetooth中,提供的常用功能有
1. BluetoothAdapter
2. BluetoothClass
3. BluetoothClass.Device
4. BluetoothClass.Device.Major
5. BluetoothClass.Service
6. BluetoothDevice
7. BluetoothServerSocket
8. BluetoothSocket
这些api允许:
app连接和断开蓝牙耳机、蓝牙打印机、蓝牙扫描仪等设备;
编写和修改本地服务的SDP协议数据库和查询其他蓝牙设备上的SDP协议数据库;
在android上建立RFCOMM协议的连接并连接到其他指定设备。
示例:学习蓝牙api的使用
// 在AndroidManifest.xml文件中声明等级和授权
<uses-sdk android:minSdkVersion=”5”/>
<uses-permission android:name=”android.permission.BLUETOOTH” />
<uses-permission android:name=”android.permission.BLUETOOTH_ADMIN” />
// 取得蓝牙适配器
BluetoothAdapter bluetooth = BluetoothAdapter.getDefaultAdapter();
// 打开蓝牙
bluetooth.enable();
// 关闭蓝牙
bluetooth.disable();
// 请求打开蓝牙常量
private static final int REQUEST_ENABLE = 0X1;
// 请求允许被搜索常量
private static final int REQUEST_DISCOVERABLE = 0X2;
// 请求打开蓝牙
Intent it = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(it, REQUEST_ENABLE);
// 请求能够被搜索
Intent it = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
startActivityForResult(it, REQUEST_DISCOVERABLE);
BluetoothAdaper中的ACTION常量
1. ACTION_DISCOVERY_FINISHED
2. ACTION_DISCOVERY_STARTED
3. ACTION_LOCAL_NAME_CHANGED
4. ACTION_REQUEST_DISCOVERABLE
5. ACTION_REQUEST_ENABLE
6. ACTION_SCAN_MODE_CHANGED
7. ACTION_STATE_CHANGED
BluetoothAdapter中的常用方法
1. cancelDiscovery
2. checkBluetoothAddress
3. disable
4. enable
5. getAddress
6. getDefalutAdpater
7. getName
8. getRemoteDevice
9. getScanMode
10. getState
11. isDiscovering
12. isEnabled
13. setName
14. startDiscovery
// 学习如何搜索网络上的设备并显示
// 搜索到一个指定地址的蓝牙设备BluetoothDevice
private BluetoothAdapter bluetooth = BluetoothAdapter.getDefaultAdapter();
private List<BluetoothDevice> devices = new ArrayList<BluetoothDevice>();
private volatile boolean discoveryFinished;
// 搜索到一个蓝牙设备
BroadcastReceiver findReceiver = new BroadcastReceiver(
public void onReceive(Context context, Intent intent) {
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
devices.add(device);
showDevices();
}
// 搜索蓝牙设备工作结束
BroadcastReceiver finishDiscoveryReceiver = new BroadcastReceiver(
public void onReceive(Context context, Intent intent) {
unregisterReceiver(findReceiver);
unregisterReceiver(this);
discoveryFinished = true;
}
);
在onCreate()方法中
// 注册Receiver
registerReceiver(finishDiscoveryReceiver, new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED));
registerReceiver(findReceiver, new IntentFilter(BluetoothAdapter.ACTION_FOUND));
// 显示对话框 正在搜索蓝牙设备
SampleUtils.indeterminate(mContext, mHandler, “扫描中…”, mDiscoveryWorker, new OnDismissListener(){
public void onDismiss(DialogInterface dialog) {
if(bluetooth.isDiscovering()){
bluetooth.cancelDiscovery();
}
discoveryFinished = true;
}
});
// mDiscoveryWorker
Runnable mDiscoveryWorker = new Runnable(){
public void run(){
bluetooth.startDiscovery();
while(!discoveryFinished){
try{
Thread.sleep(100);
}catch(InterruptedException ex){ }
}
}
};
在showDevices()方法中
List<String> data = new ArrayList<String>();
for(int i=0;i<devices.size;i++){
BluetoothDevice device = devices.get(i);
String desc = “name:(”+device.getName()+”), address:(”+device.getAddress()+”)";
data.add(desc);
}
本例的Activity继承ListActivity
final ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, list);
mHanlder.post(new Runnable(){
public void run(){
setListAdapter(adapter);
}
});
重写ListActivity的onListItemClick方法
protected void onListItemClick(ListView listView, View, view, int position, long id){
Intent it = new Intent();
it.putExtra(BluetoothDevice.EXTRA_DEVICE, devices.get(position));
setResult(RESULT_OK, it);
}