編輯:關於Android編程
最近穿戴設備發展得很火,把相關技術也帶旺了,其中一項是BLE(Bluetooth Low Energy)。BLE是藍牙4.0的核心Profile,主打功能是快速搜索,快速連接,超低功耗保持連接和傳輸數據,弱點是數據傳輸速率低,由於BLE的低功耗特點,因此普遍用於穿戴設備。Android 4.3才開始支持BLE API,所以請各位客官把本文代碼運行在藍牙4.0和Android 4.3及其以上的系統,另外本文所用的BLE終端是一個藍牙4.0的串口藍牙模塊。
注:筆者的i9100刷了4.4系統後,竟然也能跟BLE藍牙模塊通信。
BLE分為三部分Service、Characteristic、Descriptor,這三部分都由UUID作為唯一標示符。一個藍牙4.0的終端可以包含多個Service,一個Service可以包含多個Characteristic,一個Characteristic包含一個Value和多個Descriptor,一個Descriptor包含一個Value。一般來說,Characteristic是手機與BLE終端交換數據的關鍵,Characteristic有較多的跟權限相關的字段,例如PERMISSION和PROPERTY,而其中最常用的是PROPERTY,本文所用的BLE藍牙模塊竟然沒有標准的Characteristic的PERMISSION。Characteristic的PROPERTY可以通過位運算符組合來設置讀寫屬性,例如READ|WRITE、READ|WRITE_NO_RESPONSE|NOTIFY,因此讀取PROPERTY後要分解成所用的組合(本文代碼已含此分解方法)。
本文代碼改自Android 4.3 Sample的BluetoothLeGatt,把冗余代碼去掉,獲取的BLE設備信息都通過Log,還有一些必要的讀寫藍牙方法,應該算是簡化到大家一看就可以懂了。本文完整代碼可以點擊此處本站下載。
接下來貼出本文運行的結果,首先是連接BLE設備後,枚舉出設備所有Service、Characteristic、Descriptor,並且手機會往Characteristic uuid=0000ffe1-0000-1000-8000-00805f9b34fb寫入“send data->”字符串,BLE終端收到數據通過串口傳到PC串口助手:
04-21 18:28:25.465: E/DeviceScanActivity(12254): -->service type:PRIMARY
04-21 18:28:25.465: E/DeviceScanActivity(12254): -->includedServices size:0
04-21 18:28:25.465: E/DeviceScanActivity(12254): -->service uuid:00001800-0000-1000-8000-00805f9b34fb
04-21 18:28:25.465: E/DeviceScanActivity(12254): ---->char uuid:00002a00-0000-1000-8000-00805f9b34fb
04-21 18:28:25.465: E/DeviceScanActivity(12254): ---->char permission:UNKNOW
04-21 18:28:25.465: E/DeviceScanActivity(12254): ---->char property:READ
04-21 18:28:25.465: E/DeviceScanActivity(12254): ---->char uuid:00002a01-0000-1000-8000-00805f9b34fb
04-21 18:28:25.470: E/DeviceScanActivity(12254): ---->char permission:UNKNOW
04-21 18:28:25.470: E/DeviceScanActivity(12254): ---->char property:READ
04-21 18:28:25.470: E/DeviceScanActivity(12254): ---->char uuid:00002a02-0000-1000-8000-00805f9b34fb
04-21 18:28:25.470: E/DeviceScanActivity(12254): ---->char permission:UNKNOW
04-21 18:28:25.470: E/DeviceScanActivity(12254): ---->char property:READ|WRITE|
04-21 18:28:25.470: E/DeviceScanActivity(12254): ---->char uuid:00002a03-0000-1000-8000-00805f9b34fb
04-21 18:28:25.470: E/DeviceScanActivity(12254): ---->char permission:UNKNOW
04-21 18:28:25.475: E/DeviceScanActivity(12254): ---->char property:READ|WRITE|
04-21 18:28:25.475: E/DeviceScanActivity(12254): ---->char uuid:00002a04-0000-1000-8000-00805f9b34fb
04-21 18:28:25.475: E/DeviceScanActivity(12254): ---->char permission:UNKNOW
04-21 18:28:25.475: E/DeviceScanActivity(12254): ---->char property:READ
04-21 18:28:25.475: E/DeviceScanActivity(12254): -->service type:PRIMARY
04-21 18:28:25.475: E/DeviceScanActivity(12254): -->includedServices size:0
04-21 18:28:25.475: E/DeviceScanActivity(12254): -->service uuid:00001801-0000-1000-8000-00805f9b34fb
04-21 18:28:25.480: E/DeviceScanActivity(12254): ---->char uuid:00002a05-0000-1000-8000-00805f9b34fb
04-21 18:28:25.480: E/DeviceScanActivity(12254): ---->char permission:UNKNOW
04-21 18:28:25.480: E/DeviceScanActivity(12254): ---->char property:INDICATE
04-21 18:28:25.480: E/DeviceScanActivity(12254): -------->desc uuid:00002902-0000-1000-8000-00805f9b34fb
04-21 18:28:25.480: E/DeviceScanActivity(12254): -------->desc permission:UNKNOW
04-21 18:28:25.480: E/DeviceScanActivity(12254): -->service type:PRIMARY
04-21 18:28:25.480: E/DeviceScanActivity(12254): -->includedServices size:0
04-21 18:28:25.480: E/DeviceScanActivity(12254): -->service uuid:0000ffe0-0000-1000-8000-00805f9b34fb
04-21 18:28:25.480: E/DeviceScanActivity(12254): ---->char uuid:0000ffe1-0000-1000-8000-00805f9b34fb
04-21 18:28:25.480: E/DeviceScanActivity(12254): ---->char permission:UNKNOW
04-21 18:28:25.480: E/DeviceScanActivity(12254): ---->char property:READ|WRITE_NO_RESPONSE|NOTIFY|
04-21 18:28:25.490: E/DeviceScanActivity(12254): -------->desc uuid:00002902-0000-1000-8000-00805f9b34fb
04-21 18:28:25.490: E/DeviceScanActivity(12254): -------->desc permission:UNKNOW
04-21 18:28:25.490: E/DeviceScanActivity(12254): -------->desc uuid:00002901-0000-1000-8000-00805f9b34fb
04-21 18:28:25.490: E/DeviceScanActivity(12254): -------->desc permission:UNKNOW
04-21 18:28:26.025: E/DeviceScanActivity(12254): onCharRead BLE DEVICE read 0000ffe1-0000-1000-8000-00805f9b34fb -> 00
這裡紅字是由BluetoothGattCallback的onCharacteristicRead()回調而打出Log
以下Log是PC上的串口工具通過BLE模塊發送過來,由BluetoothGattCallback的 onCharacteristicChanged()打出Log
04-21 18:30:18.260: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:18.745: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:19.085: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:19.350: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:19.605: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:19.835: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:20.055: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:20.320: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:20.510: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:20.735: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
04-21 18:30:21.000: E/DeviceScanActivity(12254): onCharWrite BLE DEVICE write 0000ffe1-0000-1000-8000-00805f9b34fb -> send data to phone
接下來貼出本文核心代碼:
public class DeviceScanActivity extends ListActivity { private final static String TAG = DeviceScanActivity.class.getSimpleName(); private final static String UUID_KEY_DATA = "0000ffe1-0000-1000-8000-00805f9b34fb"; private LeDeviceListAdapter mLeDeviceListAdapter; /**搜索BLE終端*/ private BluetoothAdapter mBluetoothAdapter; /**讀寫BLE終端*/ private BluetoothLeClass mBLE; private boolean mScanning; private Handler mHandler; // Stops scanning after 10 seconds. private static final long SCAN_PERIOD = 10000; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); getActionBar().setTitle(R.string.title_devices); mHandler = new Handler(); // Use this check to determine whether BLE is supported on the device. Then you can // selectively disable BLE-related features. if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) { Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show(); finish(); } // Initializes a Bluetooth adapter. For API level 18 and above, get a reference to // BluetoothAdapter through BluetoothManager. final BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE); mBluetoothAdapter = bluetoothManager.getAdapter(); // Checks if Bluetooth is supported on the device. if (mBluetoothAdapter == null) { Toast.makeText(this, R.string.error_bluetooth_not_supported, Toast.LENGTH_SHORT).show(); finish(); return; } //開啟藍牙 mBluetoothAdapter.enable(); mBLE = new BluetoothLeClass(this); if (!mBLE.initialize()) { Log.e(TAG, "Unable to initialize Bluetooth"); finish(); } //發現BLE終端的Service時回調 mBLE.setOnServiceDiscoverListener(mOnServiceDiscover); //收到BLE終端數據交互的事件 mBLE.setOnDataAvailableListener(mOnDataAvailable); } @Override protected void onResume() { super.onResume(); // Initializes list view adapter. mLeDeviceListAdapter = new LeDeviceListAdapter(this); setListAdapter(mLeDeviceListAdapter); scanLeDevice(true); } @Override protected void onPause() { super.onPause(); scanLeDevice(false); mLeDeviceListAdapter.clear(); mBLE.disconnect(); } @Override protected void onStop() { super.onStop(); mBLE.close(); } @Override protected void onListItemClick(ListView l, View v, int position, long id) { final BluetoothDevice device = mLeDeviceListAdapter.getDevice(position); if (device == null) return; if (mScanning) { mBluetoothAdapter.stopLeScan(mLeScanCallback); mScanning = false; } mBLE.connect(device.getAddress()); } private void scanLeDevice(final boolean enable) { if (enable) { // Stops scanning after a pre-defined scan period. mHandler.postDelayed(new Runnable() { @Override public void run() { mScanning = false; mBluetoothAdapter.stopLeScan(mLeScanCallback); invalidateOptionsMenu(); } }, SCAN_PERIOD); mScanning = true; mBluetoothAdapter.startLeScan(mLeScanCallback); } else { mScanning = false; mBluetoothAdapter.stopLeScan(mLeScanCallback); } invalidateOptionsMenu(); } /** * 搜索到BLE終端服務的事件 */ private BluetoothLeClass.OnServiceDiscoverListener mOnServiceDiscover = new OnServiceDiscoverListener(){ @Override public void onServiceDiscover(BluetoothGatt gatt) { displayGattServices(mBLE.getSupportedGattServices()); } }; /** * 收到BLE終端數據交互的事件 */ private BluetoothLeClass.OnDataAvailableListener mOnDataAvailable = new OnDataAvailableListener(){ /** * BLE終端數據被讀的事件 */ @Override public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) { if (status == BluetoothGatt.GATT_SUCCESS) Log.e(TAG,"onCharRead "+gatt.getDevice().getName() +" read " +characteristic.getUuid().toString() +" -> " +Utils.bytesToHexString(characteristic.getValue())); } /** * 收到BLE終端寫入數據回調 */ @Override public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) { Log.e(TAG,"onCharWrite "+gatt.getDevice().getName() +" write " +characteristic.getUuid().toString() +" -> " +new String(characteristic.getValue())); } }; // Device scan callback. private BluetoothAdapter.LeScanCallback mLeScanCallback = new BluetoothAdapter.LeScanCallback() { @Override public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) { runOnUiThread(new Runnable() { @Override public void run() { mLeDeviceListAdapter.addDevice(device); mLeDeviceListAdapter.notifyDataSetChanged(); } }); } }; private void displayGattServices(List<BluetoothGattService> gattServices) { if (gattServices == null) return; for (BluetoothGattService gattService : gattServices) { //-----Service的字段信息-----// int type = gattService.getType(); Log.e(TAG,"-->service type:"+Utils.getServiceType(type)); Log.e(TAG,"-->includedServices size:"+gattService.getIncludedServices().size()); Log.e(TAG,"-->service uuid:"+gattService.getUuid()); //-----Characteristics的字段信息-----// List<BluetoothGattCharacteristic> gattCharacteristics =gattService.getCharacteristics(); for (final BluetoothGattCharacteristic gattCharacteristic: gattCharacteristics) { Log.e(TAG,"---->char uuid:"+gattCharacteristic.getUuid()); int permission = gattCharacteristic.getPermissions(); Log.e(TAG,"---->char permission:"+Utils.getCharPermission(permission)); int property = gattCharacteristic.getProperties(); Log.e(TAG,"---->char property:"+Utils.getCharPropertie(property)); byte[] data = gattCharacteristic.getValue(); if (data != null && data.length > 0) { Log.e(TAG,"---->char value:"+new String(data)); } //UUID_KEY_DATA是可以跟藍牙模塊串口通信的Characteristic if(gattCharacteristic.getUuid().toString().equals(UUID_KEY_DATA)){ //測試讀取當前Characteristic數據,會觸發mOnDataAvailable.onCharacteristicRead() mHandler.postDelayed(new Runnable() { @Override public void run() { mBLE.readCharacteristic(gattCharacteristic); } }, 500); //接受Characteristic被寫的通知,收到藍牙模塊的數據後會觸發mOnDataAvailable.onCharacteristicWrite() mBLE.setCharacteristicNotification(gattCharacteristic, true); //設置數據內容 gattCharacteristic.setValue("send data->"); //往藍牙模塊寫入數據 mBLE.writeCharacteristic(gattCharacteristic); } //-----Descriptors的字段信息-----// List<BluetoothGattDescriptor> gattDescriptors = gattCharacteristic.getDescriptors(); for (BluetoothGattDescriptor gattDescriptor : gattDescriptors) { Log.e(TAG, "-------->desc uuid:" + gattDescriptor.getUuid()); int descPermission = gattDescriptor.getPermissions(); Log.e(TAG,"-------->desc permission:"+ Utils.getDescPermission(descPermission)); byte[] desData = gattDescriptor.getValue(); if (desData != null && desData.length > 0) { Log.e(TAG, "-------->desc value:"+ new String(desData)); } } } }// } }
感興趣的讀者可以動手測試一下代碼的運行情況,希望能對大家的Android項目開發有所幫助。
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