无法使用 Android 6.0 或更高版本扫描 BLE 设备答案

【问题标题】：Cannot scan BLE device with Android 6.0 or later无法使用 Android 6.0 或更高版本扫描 BLE 设备
【发布时间】：2018-03-02 17:11:44
【问题描述】：

我在 Android 中有一个奇怪的错误。我正在构建一个可以连接到 BLE 设备的应用程序。对于我的测试，我使用的是带有 Android 5.1.1 的三星 J3，一切正常。

现在我尝试在运行 Android 6.0 的 Android 设备上安装我的应用程序，但我无法扫描 BLE 设备。

这是我的 Gradle 文件：

apply plugin: 'com.android.application'

android {
    compileSdkVersion 25
    buildToolsVersion '26.0.2'
    defaultConfig {
        applicationId "com.devicesensor"
        minSdkVersion 15
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        vectorDrawables.useSupportLibrary = true
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support:appcompat-v7:25.2.0'
    compile 'com.android.support:design:25.2.0'
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:cardview-v7:25.2.0'
}

这是我的扫描活动课程：

public class DeviceScanActivity extends ListActivity{

    private LeDeviceListAdapter mLeDeviceListAdapter;
    private BluetoothAdapter mBluetoothAdapter;
    private boolean mScanning;
    private Handler mHandler;

    private static final int REQUEST_ENABLE_BT = 1;
    // Stops scanning after 10 seconds.
    private static final long SCAN_PERIOD = 10000;


    @SuppressLint("NewApi")
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        getListView().setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1, int position,
                                    long arg3) {
                BluetoothDevice bDevice = mLeDeviceListAdapter.getDevice(position);
                Intent intent = new Intent();
                intent.putExtra("deviceSelected", bDevice);
                setResult(RESULT_OK, intent);
                finish();
            }
        });
       // getActionBar().setTitle("TITOLO");
        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;
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_bleactivity, menu);
        if (!mScanning) {
            menu.findItem(R.id.menu_stop).setVisible(false);
            menu.findItem(R.id.menu_scan).setVisible(true);
            menu.findItem(R.id.menu_refresh).setActionView(null);
        } else {
            menu.findItem(R.id.menu_stop).setVisible(true);
            menu.findItem(R.id.menu_scan).setVisible(false);
            menu.findItem(R.id.menu_refresh).setActionView(
                    R.layout.actionbar_indeterminate_progress);
        }
        return true;
    }

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.menu_scan:
                mLeDeviceListAdapter.clear();
                scanLeDevice(true);
                break;
            case R.id.menu_stop:
                scanLeDevice(false);
                break;
        }
        return true;
    }

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
    @Override
    protected void onResume() {
        super.onResume();
        // Ensures Bluetooth is enabled on the device.  If Bluetooth is not currently enabled,
        // fire an intent to display a dialog asking the user to grant permission to enable it.
        if (!mBluetoothAdapter.isEnabled()) {
            if (!mBluetoothAdapter.isEnabled()) {
                Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
            }
        }
        // Initializes list view adapter.
        mLeDeviceListAdapter = new LeDeviceListAdapter();
        setListAdapter(mLeDeviceListAdapter);
        scanLeDevice(true);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // User chose not to enable Bluetooth.
        if (requestCode == REQUEST_ENABLE_BT && resultCode == Activity.RESULT_CANCELED) {
            finish();
            return;
        }
        super.onActivityResult(requestCode, resultCode, data);
    }

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
    @Override
    protected void onPause() {
        super.onPause();
        scanLeDevice(false);
        mLeDeviceListAdapter.clear();
    }

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
    private void scanLeDevice(final boolean enable) {
        if (enable) {
            // Stops scanning after a pre-defined scan period.
            mHandler.postDelayed(new Runnable() {
                @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
                @Override
                public void run() {
                    mScanning = false;
                    mBluetoothAdapter.stopLeScan(mLeScanCallback);
                    invalidateOptionsMenu();
                }
            }, SCAN_PERIOD);
            mScanning = true;
            mBluetoothAdapter.startLeScan(mLeScanCallback);
        } else {
            mScanning = false;
            mBluetoothAdapter.stopLeScan(mLeScanCallback);
        }
        invalidateOptionsMenu();
    }

    // Adapter for holding devices found through scanning.
    private class LeDeviceListAdapter extends BaseAdapter {
        private ArrayList<BluetoothDevice> mLeDevices;
        private LayoutInflater mInflator;

        public LeDeviceListAdapter() {
            super();
            mLeDevices = new ArrayList<BluetoothDevice>();
            mInflator = DeviceScanActivity.this.getLayoutInflater();
        }

        public void addDevice(BluetoothDevice device) {
            if (!mLeDevices.contains(device)) {
                mLeDevices.add(device);
            }
        }

        public BluetoothDevice getDevice(int position) {
            return mLeDevices.get(position);
        }

        public void clear() {
            mLeDevices.clear();
        }

        @Override
        public int getCount() {
            return mLeDevices.size();
        }

        @Override
        public Object getItem(int i) {
            return mLeDevices.get(i);
        }

        @Override
        public long getItemId(int i) {
            return i;
        }

        @Override
        public View getView(int i, View view, ViewGroup viewGroup) {
            ViewHolder viewHolder;
            // General ListView optimization code.
            if (view == null) {
                view = mInflator.inflate(R.layout.listitem_device, null);
                viewHolder = new ViewHolder();
                viewHolder.deviceAddress = (TextView) view.findViewById(R.id.device_address);
                viewHolder.deviceName = (TextView) view.findViewById(R.id.device_name);
                view.setTag(viewHolder);
            } else {
                viewHolder = (ViewHolder) view.getTag();
            }

            BluetoothDevice device = mLeDevices.get(i);
            final String deviceName = device.getName();
            if (deviceName != null && deviceName.length() > 0)
                viewHolder.deviceName.setText(deviceName);
            else
                viewHolder.deviceName.setText(R.string.unknown_device);
            viewHolder.deviceAddress.setText(device.getAddress());

            return view;
        }
    }

    // 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();
                        }
                    });
                }
            };

    static class ViewHolder {
        TextView deviceName;
        TextView deviceAddress;
    }

【问题讨论】：

请准确描述您如何“无法使用”该应用程序。你可以启动应用程序吗？它会崩溃吗？还是只是没有收到蓝牙信号？
抱歉，如果我尝试在装有 Android 7.0 的智能手机中启动我的应用程序，我看不到蓝牙设备。如果我用 Android 5.0.1 启动我的智能手机的这个应用程序，我可以看到所有蓝牙设备。

标签： android bluetooth-lowenergy

【解决方案1】：

如果您的目标是 API 级别 23+ 并在运行 Android 6.0+ 的设备上运行，则必须在运行时向用户询问权限。要扫描蓝牙设备，您需要 ACCESS_COARSE_LOCATION / ACCESS_FINE_LOCATION。

您可以在 Android Developers Site 上找到如何执行此操作。

【讨论】：

【解决方案2】：

您可以使用BluetoothLeScanner 从 API 级别：21 发现低功耗蓝牙设备。它可以使用 ScanFilter 扫描特定类型的低功耗蓝牙设备。它还可以请求不同类型的回调来传递结果。

使用getBluetoothLeScanner() 获取BluetoothLeScanner 的实例。

注意：这里的大部分扫描方法都需要BLUETOOTH_ADMIN权限。

您可以查看this 示例以即时实现它。

另外，请确保在开始之前获得以下权限扫描，显然您还必须从安卓6.0。

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

您可以使用新的SettingsClient API 打开定位服务。

如果您想声明您的应用仅适用于支持 BLE 的设备，请在您的应用清单中包含以下内容：

<uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/>

BLE Scanner 应用程序可用于列出范围内可用的 BLE 设备以进行调试。

【讨论】：