android bluetooth

来源:互联网 发布:数据库与数据挖掘论文 编辑:程序博客网 时间:2024/03/28 19:01

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-permissionandroid:name="android.permission.BLUETOOTH"/> 
2    <uses-permissionandroid: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 = newIntent(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 finalBroadcastReceiver mReceiver = newBroadcastReceiver() { 
03    publicvoid 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 = newIntentFilter(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 classAcceptThread extends Thread {
02    privatefinal BluetoothServerSocket mmServerSocket;
03 
04    publicAcceptThread() {
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    publicvoid 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    publicvoid 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>    privateclass ConnectThread extendsThread { 
02        privatefinal BluetoothSocket mmSocket; 
03        privatefinal BluetoothDevice mmDevice; 
04       
05        publicConnectThread(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        publicvoid 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        publicvoid 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>    privateclass ConnectedThread extendsThread { 
02        privatefinal BluetoothSocket mmSocket; 
03        privatefinal InputStream mmInStream; 
04        privatefinal OutputStream mmOutStream; 
05       
06        publicConnectedThread(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        publicvoid run() { 
23            byte[] buffer =new byte[1024]; // buffer store for the stream 
24            intbytes; // 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        publicvoid cancel() { 
49            try
50                mmSocket.close(); 
51            }catch (IOException e) { } 
52        
53    }  </strong>
原创粉丝点击