蓝牙低能量:未检测到RFDuino

Question

我正在尝试编程一个应用程序，以在Android手机和RFDuino之间通过BLE建立基本通信。RFDuino只是一个广告，可以通过"BLE扫描仪"应用程序检测到。下面是活动的代码草案，该活动应该检测BLE设备

问题是，没有检测到任何设备。调试日志显示，方法"onLeScan"甚至没有被调用过一次

我的想法用完了，我会感谢每一个提示：-）

package de.tuhh.et5.serialcommunicator;
import (...)
public class BLEActivity extends AppCompatActivity {
    private static final long SCAN_PERIOD = 10000;
    private int REQUEST_ENABLE_BT = 1;
    public final static String TAG = "BLE_Activity"; // Tag for the LOG
    private BluetoothAdapter ble_adapter;
    private boolean scanning;
    private Handler ble_handler;
    private BLE_DeviceListAdapter BLE_DeviceListAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        d("on Create");
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_ble);          
        TabHost tabHost=(TabHost)findViewById(R.id.tabHost);
        tabHost.setup();
        TabHost.TabSpec t1=tabHost.newTabSpec("Tab1");
        t1.setContent(R.id.tab1_layout);
        t1.setIndicator("Devices");
        tabHost.addTab(t1);
        BLE_DeviceListAdapter = new BLE_DeviceListAdapter();
       ListView ble_list = (ListView)findViewById(R.id.BLE_DeviceListView);
        ble_list.setAdapter(BLE_DeviceListAdapter);
        ble_handler = new Handler();
        // get a bluetooth adapter from the bluetooth manager
        final BluetoothManager bluetoothManager =
                (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
        ble_adapter = bluetoothManager.getAdapter();
        // Check if BLE is supported by the Android device
        if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
            Toast.makeText(this, "BLE Not Supported",
                    Toast.LENGTH_SHORT).show();
            finish();
        }
        // Enable bluetooth
        if (ble_adapter == null || !ble_adapter.isEnabled()) {
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
        }
    }

    // menu stuff
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        d("menu inflates");
        // Inflate the menu; this adds items to the action bar if it is present.
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.ble_menu, menu);
        if (scanning) {
            menu.findItem(R.id.scanning_start).setVisible(false);
        } else {
            menu.findItem(R.id.scanning_start).setVisible(true);
        }
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.scanning_start:
                d("scan pressed");
                BLE_DeviceListAdapter.clear();
                ble_scan(true);
                break;
        }
        return true;
    }
    private void ble_scan(final boolean en){
        d("Scan start");
        // stopLeScan and startLeScan are deprecated since Android 5.0, but still work.
        // to offer a compatibility down to Android 4.3 the old methods are used
        if (en){
            ble_handler.postDelayed(new Runnable() {
                @Override
                public void run() {
                    d("scan timer finished");
                    scanning = false;
                    ble_adapter.stopLeScan(ble_callback);
                    invalidateOptionsMenu();
                }
            },SCAN_PERIOD);
            scanning = true;
            ble_adapter.startLeScan(ble_callback);
        }else{
            scanning = false;
            ble_adapter.stopLeScan(ble_callback);
        }
        invalidateOptionsMenu();
    }
    private BluetoothAdapter.LeScanCallback ble_callback = new BluetoothAdapter.LeScanCallback(){
        @Override
        public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord){
            d("onLeScan");
            runOnUiThread(new Runnable(){
                @Override
                public void run(){
                    BLE_DeviceListAdapter.addDevice(device);
                    BLE_DeviceListAdapter.notifyDataSetChanged();
                }
            });
        }
    };

    // This class lists the elements in an ble device entry as defined in "ble_device_entry.cml"
    // It is needed in the BLE_DeviceListAdapter class
    private class ViewHolder {
        TextView name;
        TextView device_id;
        TextView device_adress;
    }
    // #####################################################
    // private Class BLE_DeviceListAdapter
    //
    // Adapter to handle found BLE Devices
    // #####################################################
    private class BLE_DeviceListAdapter extends BaseAdapter{
        private ArrayList<BluetoothDevice> ble_devices; // holds found devices
        private LayoutInflater ble_inflater;            // layout inflater
        public BLE_DeviceListAdapter(){
            super();
            // Init
            ble_devices = new ArrayList<>();
            ble_inflater = BLEActivity.this.getLayoutInflater();
        }
        // method to add a device
        public void addDevice(BluetoothDevice ble_device){
            // device is added, if it is not already in the list
            if (!ble_devices.contains(ble_device)){
                ble_devices.add(ble_device);
            }
        }
        // Mandatory, returns device at position ...
        @Override
        public BluetoothDevice getItem(int position){
            return ble_devices.get(position);
        }
        // clear list..
        public void clear(){
            ble_devices.clear();
        }
        // Mandatory: Not needed, therefore just a dummy
        @Override
        public long getItemId(int i) {
            return i;
        }
        // Mandatory: returns size of list
        @Override
        public int getCount() {
            return ble_devices.size();
        }
        // Mandatory: creates and returns view with a device entry
        @Override
        public View getView(int i, View view, ViewGroup viewGroup ){
            ViewHolder viewHolder; // create view holder
            // if the view does not already exist:
            if (view == null){
                view = ble_inflater.inflate(R.layout.ble_device_entry, null);// inflate view
                viewHolder = new ViewHolder(); // create a ViewHolder
                // Connenct the ViewHolder elements to layout elements
                viewHolder.name = (TextView)findViewById(R.id.BLE_sName);
                viewHolder.device_adress = (TextView)findViewById(R.id.BLE_sAdress);
                viewHolder.device_id = (TextView)findViewById(R.id.BLE_sID);
                view.setTag(viewHolder); // Add the ViewHolder as a Tag to the view
            }else{
                // if the view already exists
                viewHolder = (ViewHolder) view.getTag(); // get Tag from view to populate ViewHolder
            }
            // get BLE Device
            Log.d("test", "hier so....");
            BluetoothDevice device = ble_devices.get(i);
            // get device name
            final String deviceName = device.getName();
            // assign device name to ViewHolder Object
            if (deviceName != null && deviceName.length() > 0){
                viewHolder.device_id.setText(deviceName);
            }else viewHolder.device_id.setText(R.string.unknown_ble_device);
            // assign more values
            viewHolder.device_adress.setText(device.getAddress());
            viewHolder.name.setText(R.string.unknown_ble_device);
            d("before return view");
            return view;
        }
    }
    // #####################################################
    // End Adapter
    // #####################################################
    public void d(Object msg) {
        Log.d(TAG, ">==< " + msg.toString() + " >==<");
    }
    public void e(Object msg) {
        Log.e(TAG, ">==< " + msg.toString() + " >==<");
    }
}

Answer 1

好吧，我好像把权限搞砸了。我没有该位置的运行时权限。我认为基于清单的权限已经足够了，如果不排除任何目标Android 6.xx。现在我在视图持有者和其他方面有问题，但这是另一个故事：-）。

无论如何，感谢MarkusKauppinen的解决方案！

Answer 2

在我看来，扫描代码看起来还可以。

需要检查的一些事项：

您是否调试/记录以检查选项菜单是否正常工作并且调用了ble_scan()？

您是否调试/记录以检查startLeScan()是否返回true？

如果未找到任何设备，则不会调用onLeScan()回调。

由于你扫描了10秒，RFDuino应该经常/长时间地做广告，在10秒的窗口内至少有一个广告周期。

所有Android版本都需要这些权限：

android.permission.BLUETOOTH
android.permission.BLUETOOTH_ADMIN

此外，Android 6.x（Marhsmallow）及更高版本还需要：

android.permission.ACCESS_COARSE_LOCATION

如果您编写的代码仅针对6.x及更高版本，则需要使用新的运行时权限模型，而不是基于旧的清单文件。

在一些运行Android 6.x的设备上，系统范围的"位置"设置必须为On。请参阅：onLeScan from BluetoothAdapter.LeScanCallback not called in Android Marshmallow

当然，一些旧的讨论可能会有一些有用的提示。