[安卓] 20、基于蓝牙BLE的广播包高频快速搜索

时间 2019-11-05

标签基于蓝牙 ble 广播高频快速搜索栏目 Android 繁體版

原文原文链接

前言：

以前介绍过不少蓝牙beacon、搜索、链接、通信的文章。不过最近我发现：以前写的蓝牙广播包搜索的工程，搜索频率太慢，并且不能一直保持搜索状态。所以，这里探讨下高频蓝牙广播包扫描 —— 蓝牙BLE扫描。html

注：本文将从对比以前慢的和如今快的两个工程进行展开java

一、初始化-onCreate

新的：linux

// 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：android

// 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：老的是经过注册广播过滤条件BluetoothDevice.ACTION_FOUND和BluetoothAdapter.ACTION_DISCOVERY_FINISHED，来实现监听蓝牙设备扫描的发现和中止扫描事件。而mReceiver则是回调函数，接下来会介绍；新的暂时看不出啥头绪，仅仅得到bluetoothManager和mBluetoothAdapter，接下来会用到。git

二、开始扫描-doDiscovery

新的：github

// 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：app

// 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操做、一个是普通蓝牙操做。dom

三、监听

新的：ide

// 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：函数

// 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、能够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、最后中止扫描了还有个FINISH事件，这里我在FINISH事件结束时发出一个msg来通知进行其余操做。

四、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。

五、最后说明

当你尝试使用BLE SCAN以后，你会感受有一种飞通常的感受，几乎同一个设备每一秒都会被扫描到屡次。拿这些高频扫描的大量数据，就能够作相似beacon、距离估算、定位等小应用了！效果会比老的scan方法要好不少～

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