android 蓝牙浅谈

最新推荐文章于 2024-06-11 19:47:00 发布

weixingyan

最新推荐文章于 2024-06-11 19:47:00 发布

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分类专栏： android 蓝牙文章标签： android

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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

01BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();  

02//直接打开系统的蓝牙设置面板   

03Intent intent = new
Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);   

04startActivityForResult(intent, 
0x1);   

05//直接打开蓝牙   

06adapter.enable();   

07//关闭蓝牙   

08adapter.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）  

10discoverableIntent.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  

02private 
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   

15IntentFilter filter = new
IntentFilter(BluetoothDevice.ACTION_FOUND);   

16registerReceiver(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）

 
01private 
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}

客户端的实现

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>

连接管理（数据通信）

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>