Android BluetoothLe Scan 什么也没找到

Question

我正在尝试修改 Android 示例中的代码connectivity-samples-main\BluetoothLeGatt\Application\src\main\java\com\example\android\bluetoothlegatt\DeviceScanActivity.java

对于我的应用程序，我尝试了所有权限，即使是不需要的权限

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

而不仅仅是

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

我的代码是

package com.embesystems.aresp32;

import static com.embesystems.aresp32.MainActivity.EXTRAS_DEVICE_ADDRESS;
import static com.embesystems.aresp32.MainActivity.EXTRAS_DEVICE_NAME;

import android.Manifest;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.ListActivity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothManager;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import com.embesystems.aresp32.databinding.ActivityScanBinding;

import java.util.ArrayList;

/**
 * Activity for scanning and displaying available Bluetooth LE devices.
 */
public class DeviceScanActivity extends AppCompatActivity {
    private static String TAG="MainActivity";
    private ActivityScanBinding binding;
    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;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = ActivityScanBinding.inflate(getLayoutInflater());
//        setContentView(binding.getRoot());
//        setSupportActionBar(binding.toolbar);
        getSupportActionBar().setTitle(R.string.title_devices);

        binding.listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Log.i(TAG, "Position=" + position);
                final BluetoothDevice device = mLeDeviceListAdapter.getDevice(position);
                if (device == null) return;
                if (mScanning) {
                    mBluetoothAdapter.stopLeScan(mLeScanCallback);
                    mScanning = false;
                }
                Intent resultIntent = new Intent();
                resultIntent.putExtra(EXTRAS_DEVICE_NAME, device.getName());
                resultIntent.putExtra(EXTRAS_DEVICE_ADDRESS, device.getAddress());
                setResult(Activity.RESULT_OK, resultIntent);
                finish();
            }
        });

        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;
        }
//        mLeDeviceListAdapter.notifyDataSetChanged();
        scanLeDevice(true);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.scan_menu, 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;
    }

    @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;
    }

    @Override
    protected void onResume() {
        super.onResume();
//            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_SCAN) != PackageManager.PERMISSION_GRANTED) {
//                // TODO: Consider calling
//                //    ActivityCompat#requestPermissions
//                // here to request the missing permissions, and then overriding
//                //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
//                //                                          int[] grantResults)
//                // to handle the case where the user grants the permission. See the documentation
//                // for ActivityCompat#requestPermissions for more details.
//                String[] perms= new String[1];
//                perms[0]=Manifest.permission.BLUETOOTH_SCAN;
//                ActivityCompat.requestPermissions( this, perms,1);
////                return;
//            }
        // 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()) {
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
//            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
//                // TODO: Consider calling
//                //    ActivityCompat#requestPermissions
//                // here to request the missing permissions, and then overriding
//                //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
//                //                                          int[] grantResults)
//                // to handle the case where the user grants the permission. See the documentation
//                // for ActivityCompat#requestPermissions for more details.
//                return;
//            }
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
        }

        // Initializes list view adapter.
        mLeDeviceListAdapter = new LeDeviceListAdapter();
        binding.listview.setAdapter(mLeDeviceListAdapter);
        mLeDeviceListAdapter.notifyDataSetChanged();
        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);
    }

    @Override
    protected void onPause() {
        super.onPause();
        scanLeDevice(false);
        mLeDeviceListAdapter.clear();
        mLeDeviceListAdapter.notifyDataSetChanged();
    }

    private void scanLeDevice(final boolean enable) {
        if (enable) {
            Log.d(TAG, "scanLeDevice");
            // 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;
//            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_SCAN) != PackageManager.PERMISSION_GRANTED) {
//                // TODO: Consider calling
//                //    ActivityCompat#requestPermissions
//                // here to request the missing permissions, and then overriding
//                //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
//                //                                          int[] grantResults)
//                // to handle the case where the user grants the permission. See the documentation
//                // for ActivityCompat#requestPermissions for more details.
//                String[] perms= new String[1];
//                perms[0]=Manifest.permission.BLUETOOTH_SCAN;
//                ActivityCompat.requestPermissions( this, perms,1);
////                return;
//            }
            Log.d(TAG, "Commence à scanner...");
            mBluetoothAdapter.startLeScan(mLeScanCallback);
        } else {
            mScanning = false;
            Log.d(TAG, "Arrête de scanner.");
            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();
            Log.d(TAG, "Init ListAdapter...");
        }

        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() {
                    Log.d(TAG, "Ajoute à liste");
                    mLeDeviceListAdapter.addDevice(device);
                    mLeDeviceListAdapter.notifyDataSetChanged();
                }
            });
        }
    };

    static class ViewHolder {
        TextView deviceName;
        TextView deviceAddress;
    }
}

我用

    compileSdk 32
...
        minSdk 21
        targetSdk 31

但我也试过targetSdk 28 and 29

到目前为止没有成功。 调试表明它开始扫描但没有结果。 我有 BLE Scanner 应用程序，它可以找到我的 ble iot 设备并连接到它。 所以问题出在我的 Android 代码/清单配置上。 有任何想法吗？ 谢谢

Answer 1

您指定的一些蓝牙权限是运行时权限。 但是，所有查询这些运行时权限的代码都被注释掉了。

您的应用程序很可能根本没有所需的权限，因此结果为空。