Question

我正在为项目开发应用程序。它使用蓝牙。我按照谷歌开发者页面设置蓝牙的步骤进行了操作。我达到了启用可发现性的阶段。问题是我想在列表视图中显示设备，但它们不会显示出来。也许有人可以指出我的笨拙，因为我无法看到问题。

public class MainActivity extends AppCompatActivity {
    private final static int REQUEST_ENABLE_BT = 1;
    Set<BluetoothDevice> pairedDevices;
    ArrayAdapter<String> deviceAdapter;
    ArrayList<String> list;
    ListView listView;
    BroadcastReceiver mReceiver;
    Intent discoverableIntent;
    IntentFilter intentFilter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView = (ListView) findViewById(R.id.devices);
        list = new ArrayList<>();
        deviceAdapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, list);
        listView.setAdapter(deviceAdapter);

        BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        if (bluetoothAdapter == null)
            Toast.makeText(this, "Bluetooth is not supported!", Toast.LENGTH_SHORT).show();
        else {
            if (!bluetoothAdapter.isEnabled()) {
                Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
            }
        }

        if (bluetoothAdapter != null) {
            pairedDevices = bluetoothAdapter.getBondedDevices();
        }
        if (pairedDevices.size() > 0) {
            for (BluetoothDevice device : pairedDevices) {
                deviceAdapter.add(device.getName() + "\n" + device.getAddress());
            }
        }

        mReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();
                if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                    BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                    deviceAdapter.add(device.getName() + "\n" + device.getAddress());
                    Log.d("BT", device.getName() + "\n" + device.getAddress());
                }
            }
        };
        intentFilter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
        registerReceiver(mReceiver, intentFilter);

        if (bluetoothAdapter.isDiscovering()) {
        bluetoothAdapter.cancelDiscovery();
    }
    bluetoothAdapter.startDiscovery();



        // ATTENTION: This was auto-generated to implement the App Indexing API.
        // See https://g.co/AppIndexing/AndroidStudio for more information.
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(mReceiver);
    }
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.szili.bluetoothclient.MainActivity">

    <ListView
        android:id="@+id/devices"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

    </ListView>
</LinearLayout>


<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.szili.bluetoothclient">
    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <!-- ATTENTION: This was auto-generated to add Google Play services to your project for
             App Indexing.  See https://g.co/AppIndexing/AndroidStudio for more information. -->
        <meta-data
            android:name="com.google.android.gms.version"
            android:value="@integer/google_play_services_version" />
    </application>

</manifest>

Answer 1

您忘了扫描设备：

// Create a BroadcastReceiver for ACTION_FOUND
private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
    public void onReceive(Context context, Intent intent) {
        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);
            // Add the name and address to an array adapter to show in a ListView
            mArrayAdapter.add(device.getName() + "\n" + device.getAddress());
        }
    }
};
// Register the BroadcastReceiver
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(mReceiver, filter); // Don't forget to unregister during onDestroy

要开始发现设备，只需致电startDiscovery() 来自：http://developer.android.com/intl/es/guide/topics/connectivity/bluetooth.html

Answer 2

经过一些研究后，我能够找出问题所在。基本上使用Android Marshmallow我需要为我的应用程序提供位置权限，否则它无法扫描附近的设备。

我的应用程序出现蓝牙问题

2 个答案: