技术联盟

Android 蓝牙4.0 BLE 理解

转载自:http://blog.csdn.net/chaoyue0071/article/details/43450183/
本文简单结合两篇文章
http://blog.csdn.net/hellogv/article/details/24267685
http://blog.csdn.net/jimoduwu/article/details/21604215
在BLE协议中,有两个角色,周边(Periphery)和中央(Central),一个中央可以同时连接多个周边,但是一个周边某一时刻只能连接一个中央。但是不管是Periphery还是Central都是可以实现 GATT server 和 GATT client去传输数据,但是无法同时都是。
大概了解了概念后,看看Android BLE SDK的四个关键类(class):
a) BluetoothGattServer作为周边来提供数据; BluetoothGattServerCallback返回周边的状态。
b) BluetoothGatt作为中央来使用和处理数据;BluetoothGattCallback返回中央的状态和周边提供的数据。
因为我们讨论的是Android的BLE SDK,下面所有的BluetoothGattServer代表周边,BluetoothGatt代表中央。

一.创建一个周边(虽然目前周边API在Android手机上不工作,但还是看看)
a)先看看周边用到的class,蓝色椭圆
这里写图片描述
b)说明:
每一个周边BluetoothGattServer,包含多个服务Service,每一个Service包含多个特征Characteristic。
1.new一个特征:character = new BluetoothGattCharacteristic(
UUID.fromString(characteristicUUID),
BluetoothGattCharacteristic.PROPERTY_NOTIFY,
BluetoothGattCharacteristic.PERMISSION_READ);
2.new一个服务:service = new BluetoothGattService(UUID.fromString(serviceUUID),
BluetoothGattService.SERVICE_TYPE_PRIMARY);
3.把特征添加到服务:service.addCharacteristic(character);
4.获取BluetoothManager:manager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
5.获取/打开周边:BluetoothGattServer server = manager.openGattServer(this,
new BluetoothGattServerCallback(){…});
6.把service添加到周边:server.addService(service);
7.开始广播service:Google还没有广播Service的API,等吧!!!!!所以目前我们还不能让一个Android手机作为周边来提供数据。

二.创建一个中央(这次不会让你失望,可以成功创建并且连接到周边的)
a)先看看中央用到的class,蓝色椭圆
这里写图片描述
b)说明:
为了拿到中央BluetoothGatt,可要爬山涉水十八弯:
1.先拿到BluetoothManager:bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
2.再拿到BluetoothAdapt:btAdapter = bluetoothManager.getAdapter();
3.开始扫描:btAdapter.startLeScan( BluetoothAdapter.LeScanCallback);
4.从LeScanCallback中得到BluetoothDevice:public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord) {…..}
5.用BluetoothDevice得到BluetoothGatt:gatt = device.connectGatt(this, true, gattCallback);
终于拿到中央BluetoothGatt了,它有一堆方法(查API吧),调用这些方法,你就可以通过BluetoothGattCallback和周边BluetoothGattServer交互了。
官方有给出BLE 通信的sample ,下面是牛人简化了代码,简化得简单明了
本文来自http://blog.csdn.net/hellogv/ ,引用必须注明出处!
最近穿戴设备发展得很火,把相关技术也带旺了,其中一项是BLE(Bluetooth Low Energy)。BLE是蓝牙4.0的核心Profile,主打功能是快速搜索,快速连接,超低功耗保持连接和传输数据,弱点是数据传输速率低,由于BLE的低功耗特点,因此普遍用于穿戴设备。Android 4.3才开始支持BLE API,所以请各位客官把本文代码运行在蓝牙4.0和Android 4.3及其以上的系统,另外本文所用的BLE终端是一个蓝牙4.0的串口蓝牙模块。
PS:我的i9100刷了4.4系统后,竟然也能跟BLE蓝牙模块通信。

BLE分为三部分Service、Characteristic、Descriptor,这三部分都由UUID作为唯一标示符。一个蓝牙4.0的终端可以包含多个Service,一个Service可以包含多个Characteristic,一个Characteristic包含一个Value和多个Descriptor,一个Descriptor包含一个Value。一般来说,Characteristic是手机与BLE终端交换数据的关键,Characteristic有较多的跟权限相关的字段,例如PERMISSION和PROPERTY,而其中最常用的是PROPERTY,本文所用的BLE蓝牙模块竟然没有标准的Characteristic的PERMISSION。Characteristic的PROPERTY可以通过位运算符组合来设置读写属性,例如READ|WRITE、READ|WRITE_NO_RESPONSE|NOTIFY,因此读取PROPERTY后要分解成所用的组合(本文代码已含此分解方法)。

本文代码改自Android 4.3 Sample的BluetoothLeGatt,把冗余代码去掉,获取的BLE设备信息都通过Log,还有一些必要的读写蓝牙方法,应该算是简化到大家一看就可以懂了。本文代码可以到http://download.csdn.net/detail/hellogv/7228819下载。接下来贴出本文运行的结果,首先是连接BLE设备后,枚举出设备所有Service、Characteristic、Descriptor,并且手机会往Characteristic uuid=0000ffe1-0000-1000-8000-00805f9b34fb写入“send data->”字符串,BLE终端收到数据通过串口传到PC串口助手(见PC串口助手的截图):
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
这里红字是由BluetoothGattCallback的onCharacteristicRead()回调而打出Log

这里写图片描述
以下Log是PC上的串口工具通过BLE模块发送过来,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

接下来贴出本文核心代码:

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终端*/  
    private BluetoothAdapter mBluetoothAdapter;  
    /**读写BLE终端*/  
    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;  
        }  
        //开启蓝牙  
        mBluetoothAdapter.enable();  

        mBLE = new BluetoothLeClass(this);  
        if (!mBLE.initialize()) {  
            Log.e(TAG, "Unable to initialize Bluetooth");  
            finish();  
        }  
        //发现BLE终端的Service时回调  
        mBLE.setOnServiceDiscoverListener(mOnServiceDiscover);  
        //收到BLE终端数据交互的事件  
        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终端服务的事件 
     */  
    private BluetoothLeClass.OnServiceDiscoverListener mOnServiceDiscover = new OnServiceDiscoverListener(){  

        @Override  
        public void onServiceDiscover(BluetoothGatt gatt) {  
            displayGattServices(mBLE.getSupportedGattServices());  
        }  

    };  

    /** 
     * 收到BLE终端数据交互的事件 
     */  
    private BluetoothLeClass.OnDataAvailableListener mOnDataAvailable = new OnDataAvailableListener(){  

        /** 
         * BLE终端数据被读的事件 
         */  
        @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终端写入数据回调 
         */  
        @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是可以跟蓝牙模块串口通信的Characteristic  
                if(gattCharacteristic.getUuid().toString().equals(UUID_KEY_DATA)){                    
                    //测试读取当前Characteristic数据,会触发mOnDataAvailable.onCharacteristicRead()  
                    mHandler.postDelayed(new Runnable() {  
                        @Override  
                        public void run() {  
                            mBLE.readCharacteristic(gattCharacteristic);  
                        }  
                    }, 500);  

                    //接受Characteristic被写的通知,收到蓝牙模块的数据后会触发mOnDataAvailable.onCharacteristicWrite()  
                    mBLE.setCharacteristicNotification(gattCharacteristic, true);  
                    //设置数据内容  
                    gattCharacteristic.setValue("send data->");  
                    //往蓝牙模块写入数据  
                    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));  
                    }  
                 }  
            }  
        }//  

    }  
}  

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码字很辛苦,转载请注明来自技术联盟《Android 蓝牙4.0 BLE 理解》

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