android bluetooth
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由于近期正在开发一个通过蓝牙进行数据传递的模块,在参考了有关资料,并详细阅读了Android的官方文档后,总结了Android中蓝牙模块的使用。
1. 使用蓝牙的响应权限
1
<
strong
> <
uses-permission
android:name
=
"android.permission.BLUETOOTH"
/>
2
<
uses-permission
android:name
=
"android.permission.BLUETOOTH_ADMIN"
/> </
strong
>
2. 配置本机蓝牙模块
在这里首先要了解对蓝牙操作一个核心类BluetoothAdapter
01
BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();
02
//直接打开系统的蓝牙设置面板
03
Intent intent =
new
Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
04
startActivityForResult(intent,
0x1
);
05
//直接打开蓝牙
06
adapter.enable();
07
//关闭蓝牙
08
adapter.disable();
09
//打开本机的蓝牙发现功能(默认打开120秒,可以将时间最多延长至300秒)
10
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION,
300
);
//设置持续时间(最多300秒)Intent discoveryIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
3.搜索蓝牙设备
使用BluetoothAdapter的startDiscovery()方法来搜索蓝牙设备
startDiscovery()方法是一个异步方法,调用后会立即返回。该方法会进行对其他蓝牙设备的搜索,该过程会持续12秒。该方法调用后,搜索过程实际上是在一个System Service中进行的,所以可以调用cancelDiscovery()方法来停止搜索(该方法可以在未执行discovery请求时调用)。
请求Discovery后,系统开始搜索蓝牙设备,在这个过程中,系统会发送以下三个广播:
ACTION_DISCOVERY_START:开始搜索
ACTION_DISCOVERY_FINISHED:搜索结束
ACTION_FOUND:找到设备,这个Intent中包含两个extra fields:EXTRA_DEVICE和EXTRA_CLASS,分别包含BluetooDevice和BluetoothClass。
我们可以自己注册相应的BroadcastReceiver来接收响应的广播,以便实现某些功能
01
// 创建一个接收ACTION_FOUND广播的BroadcastReceiver
02
private
final
BroadcastReceiver mReceiver =
new
BroadcastReceiver() {
03
public
void
onReceive(Context context, Intent intent) {
04
String action = intent.getAction();
05
// 发现设备
06
if
(BluetoothDevice.ACTION_FOUND.equals(action)) {
07
// 从Intent中获取设备对象
08
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
09
// 将设备名称和地址放入array adapter,以便在ListView中显示
10
mArrayAdapter.add(device.getName() +
"\n"
+ device.getAddress());
11
}
12
}
13
};
14
// 注册BroadcastReceiver
15
IntentFilter filter =
new
IntentFilter(BluetoothDevice.ACTION_FOUND);
16
registerReceiver(mReceiver, filter);
// 不要忘了之后解除绑定
4. 蓝牙Socket通信
如果打算建议两个蓝牙设备之间的连接,则必须实现服务器端与客户端的机制。当两个设备在同一个RFCOMM channel下分别拥有一个连接的BluetoothSocket,这两个设备才可以说是建立了连接。
服务器设备与客户端设备获取BluetoothSocket的途径是不同的。服务器设备是通过accepted一个incoming connection来获取的,而客户端设备则是通过打开一个到服务器的RFCOMM channel来获取的。
服务器端的实现
通过调用BluetoothAdapter的listenUsingRfcommWithServiceRecord(String, UUID)方法来获取BluetoothServerSocket(UUID用于客户端与服务器端之间的配对)
调用BluetoothServerSocket的accept()方法监听连接请求,如果收到请求,则返回一个BluetoothSocket实例(此方法为block方法,应置于新线程中)
如果不想在accept其他的连接,则调用BluetoothServerSocket的close()方法释放资源(调用该方法后,之前获得的BluetoothSocket实例并没有close。但由于RFCOMM一个时刻只允许在一条channel中有一个连接,则一般在accept一个连接后,便close掉BluetoothServerSocket)
01
private
class
AcceptThread
extends
Thread {
02
private
final
BluetoothServerSocket mmServerSocket;
03
04
public
AcceptThread() {
05
// Use a temporary object that is later assigned to mmServerSocket,
06
// because mmServerSocket is final
07
BluetoothServerSocket tmp =
null
;
08
try
{
09
// MY_UUID is the app's UUID string, also used by the client code
10
tmp = mBluetoothAdapter.listenUsingRfcommWithServiceRecord(NAME, MY_UUID);
11
}
catch
(IOException e) { }
12
mmServerSocket = tmp;
13
}
14
15
public
void
run() {
16
BluetoothSocket socket =
null
;
17
// Keep listening until exception occurs or a socket is returned
18
while
(
true
) {
19
try
{
20
socket = mmServerSocket.accept();
21
}
catch
(IOException e) {
22
break
;
23
}
24
// If a connection was accepted
25
if
(socket !=
null
) {
26
// Do work to manage the connection (in a separate thread)
27
manageConnectedSocket(socket);
28
mmServerSocket.close();
29
break
;
30
}
31
}
32
}
33
34
/** Will cancel the listening socket, and cause the thread to finish */
35
public
void
cancel() {
36
try
{
37
mmServerSocket.close();
38
}
catch
(IOException e) { }
39
}
40
}
通过搜索得到服务器端的BluetoothService
调用BluetoothService的listenUsingRfcommWithServiceRecord(String, UUID)方法获取BluetoothSocket(该UUID应该同于服务器端的UUID)
调用BluetoothSocket的connect()方法(该方法为block方法),如果UUID同服务器端的UUID匹配,并且连接被服务器端accept,则connect()方法返回
注意:在调用connect()方法之前,应当确定当前没有搜索设备,否则连接会变得非常慢并且容易失败
01
<strong>
private
class
ConnectThread
extends
Thread {
02
private
final
BluetoothSocket mmSocket;
03
private
final
BluetoothDevice mmDevice;
04
05
public
ConnectThread(BluetoothDevice device) {
06
// Use a temporary object that is later assigned to mmSocket,
07
// because mmSocket is final
08
BluetoothSocket tmp =
null
;
09
mmDevice = device;
10
11
// Get a BluetoothSocket to connect with the given BluetoothDevice
12
try
{
13
// MY_UUID is the app's UUID string, also used by the server code
14
tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
15
}
catch
(IOException e) { }
16
mmSocket = tmp;
17
}
18
19
public
void
run() {
20
// Cancel discovery because it will slow down the connection
21
mBluetoothAdapter.cancelDiscovery();
22
23
try
{
24
// Connect the device through the socket. This will block
25
// until it succeeds or throws an exception
26
mmSocket.connect();
27
}
catch
(IOException connectException) {
28
// Unable to connect; close the socket and get out
29
try
{
30
mmSocket.close();
31
}
catch
(IOException closeException) { }
32
return
;
33
}
34
35
// Do work to manage the connection (in a separate thread)
36
manageConnectedSocket(mmSocket);
37
}
38
39
/** Will cancel an in-progress connection, and close the socket */
40
public
void
cancel() {
41
try
{
42
mmSocket.close();
43
}
catch
(IOException e) { }
44
}
45
} </strong>
分别通过BluetoothSocket的getInputStream()和getOutputStream()方法获取InputStream和OutputStream
使用read(bytes[])和write(bytes[])方法分别进行读写操作
注意:read(bytes[])方法会一直block,知道从流中读取到信息,而write(bytes[])方法并不是经常的block(比如在另一设备没有及时read或者中间缓冲区已满的情况下,write方法会block)
01
<strong>
private
class
ConnectedThread
extends
Thread {
02
private
final
BluetoothSocket mmSocket;
03
private
final
InputStream mmInStream;
04
private
final
OutputStream mmOutStream;
05
06
public
ConnectedThread(BluetoothSocket socket) {
07
mmSocket = socket;
08
InputStream tmpIn =
null
;
09
OutputStream tmpOut =
null
;
10
11
// Get the input and output streams, using temp objects because
12
// member streams are final
13
try
{
14
tmpIn = socket.getInputStream();
15
tmpOut = socket.getOutputStream();
16
}
catch
(IOException e) { }
17
18
mmInStream = tmpIn;
19
mmOutStream = tmpOut;
20
}
21
22
public
void
run() {
23
byte
[] buffer =
new
byte
[
1024
];
// buffer store for the stream
24
int
bytes;
// bytes returned from read()
25
26
// Keep listening to the InputStream until an exception occurs
27
while
(
true
) {
28
try
{
29
// Read from the InputStream
30
bytes = mmInStream.read(buffer);
31
// Send the obtained bytes to the UI Activity
32
mHandler.obtainMessage(MESSAGE_READ, bytes, -
1
, buffer)
33
.sendToTarget();
34
}
catch
(IOException e) {
35
break
;
36
}
37
}
38
}
39
40
/* Call this from the main Activity to send data to the remote device */
41
public void write(byte[] bytes) {
42
try {
43
mmOutStream.write(bytes);
44
} catch (IOException e) { }
45
}
46
47
/* Call this from the main Activity to shutdown the connection */
48
public
void
cancel() {
49
try
{
50
mmSocket.close();
51
}
catch
(IOException e) { }
52
}
53
} </strong>
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