[安卓] 20、基于蓝牙BLE的广播包高频快速搜索


前言:

之前介绍过很多蓝牙beacon、搜索、连接、通讯的文章。不过最近我发现:之前写的蓝牙广播包搜索的工程,搜索频率太慢,而且不能一直保持搜索状态。因此,这里探讨下高频蓝牙广播包扫描 —— 蓝牙BLE扫描。

注:本文将从对比之前慢的和现在快的两个工程进行展开

 

1、初始化-onCreate

新的:

// Get the local Bluetooth adapter
// Initializes Bluetooth adapter.
final BluetoothManager bluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();

// Ensures Bluetooth is available on the device and it is enabled. If not,
// displays a dialog requesting user permission to enable Bluetooth.
if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) {
    Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
    startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}

老的:

// Register for broadcasts when a device is discovered
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
this.registerReceiver(mReceiver, filter);
// Register for broadcasts when discovery has finished
filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
this.registerReceiver(mReceiver, filter);

// Get the local Bluetooth adapter
mBtAdapter = BluetoothAdapter.getDefaultAdapter();

可见:老的是通过注册广播过滤条件BluetoothDevice.ACTION_FOUNDBluetoothAdapter.ACTION_DISCOVERY_FINISHED,来实现监听蓝牙设备扫描的发现和停止扫描事件。而mReceiver则是回调函数,接下来会介绍;新的暂时看不出啥头绪,仅仅获得bluetoothManagermBluetoothAdapter,接下来会用到。

 

2、开始扫描-doDiscovery

新的:

// Start device discover with the BluetoothAdapter
private void doDiscovery() {
    // If we're already discovering, stop it
    if (mBluetoothAdapter.isDiscovering()) {
        mBluetoothAdapter.stopLeScan(mLeScanCallback);
    }
    // Request discover from BluetoothAdapter
    //use filter not work!!!!!!!!!!
    //UUID[] uuid_arrays = new UUID[1];
    //uuid_arrays[0] = ParcelUuid.fromString(UUID_SERVICE).getUuid();
    //mBluetoothAdapter.startLeScan(uuid_arrays,mLeScanCallback);
    //Log.d("RSSI",uuid_arrays[0].toString() + "  " + UUID.randomUUID().toString());
    mBluetoothAdapter.startLeScan(mLeScanCallback);
}

老的:

// Start device discover with the BluetoothAdapter
private void doDiscovery() {
    // If we're already discovering, stop it
    if (mBtAdapter.isDiscovering()) {
        mBtAdapter.cancelDiscovery();
    }
    // Request discover from BluetoothAdapter
    mBtAdapter.startDiscovery();
}

可见:区别在于一个是BLE操作、一个是普通蓝牙操作。

 

3、监听

新的:

// 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() {
                if(device_filter(device)){
                    //mDevicesNameVector.add(device.getName());
                    //mDevicesAddrVector.add(device.getAddress());
                    //mRSSIVector.add((short)rssi);
                    Log.d("RSSI",device.getAddress() + " " + device.getName() + " " + String.valueOf(rssi));
                    ...
                }
            }
        });
    }
};

老的:

// The BroadcastReceiver that listens for discovered devices and
// changes the title when discovery is finished
//【查找蓝牙设备】
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.d("onReceive","OK");
        String action = intent.getAction();
        // When discovery finds a device
        if (BluetoothDevice.ACTION_FOUND.equals(action)) {
            // Get the BluetoothDevice object from the Intent
            BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
            mDevicesNameVector.add(device.getName());
            mDevicesAddrVector.add(device.getAddress());
            short rssi = intent.getExtras().getShort(BluetoothDevice.EXTRA_RSSI);
            mRSSIVector.add(rssi);
            Log.d("RSSI",device.getName()+"  "+String.valueOf(rssi));
            // When discovery is finished, change the Activity title
        } else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
            setProgressBarIndeterminateVisibility(false);
            if (mDevicesNameVector.size() != 0) {
                Message msg = new Message();//消息
                Bundle bundle = new Bundle();
                bundle.clear();Log.d("onReceive","1");
                msg.what = 0x01;//消息类别
                bundle.putShort("msg",(short) 0);Log.d("onReceive","2");
                    msg.setData(bundle);Log.d("onReceive","3");
                    myHandler.sendMessage(msg);Log.d("onReceive","4");
            }
        }
    }
};

可见:新的相对比较简单、可以持续不断的扫描获取(同一个设备会被不断的扫描到);老的则分为两步:第一步是每次扫描到一次新设备都会有一个FOUND事件、最后停止扫描了还有个FINISH事件,这里我在FINISH事件结束时发出一个msg来通知进行其他操作。

 

4、权限文件配置

新的:

<uses-permission a:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission a:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission a:name="android.permission.BLUETOOTH"/>
<uses-permission a:name="android.permission.BLUETOOTH_ADMIN"/>
<uses-feature a:name="android.hardware.bluetooth_le" a:required="true"/>

老的:

<uses-permission a:name="android.permission.BLUETOOTH" />
<uses-permission a:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission a:name="android.permission.ACCESS_COARSE_LOCATION" />

可见:相差不大,新的比老的多了bluetooth_le说明。

 

5、最后说明

当你尝试使用BLE SCAN之后,你会感觉有一种飞一般的感觉,几乎同一个设备每一秒都会被扫描到多次。拿这些高频扫描的大量数据,就可以做类似beacon、距离估算、定位等小应用了!效果会比老的scan方法要好很多~


[1]. 本项目GITHUB链接地址
[2]. 在Linux下搭建安卓APP的开发烧写环境(makefile版)—— 在Linux上用命令行+VIM开发安卓APP
[3]. android developer TextView
[4]. android developer Vector
[5]. android developer String
[6]. android developer Formatter
[7]. android developer Matcher
[8]. android developer Pattern
[9]. 等宽字体-Android 设置字体的三种方法(TypeFace)
[10]. Android 设置TextView滑动滚动条和滑动效果


@beautifulzzzz
智能硬件、物联网,热爱技术,关注产品
博客:http://blog.beautifulzzzz.com
园友交流群:414948975
posted @ 2018-12-11 02:13 beautifulzzzz 阅读(...) 评论(...) 编辑 收藏