无法发现对等点 - Wifi Direct-

Question

我想在同一本地网络上的两台安卓设备之间建立连接，并通过我的安卓应用在它们之间交换数据。 为了达到这个目的，我使用了带有广播接收器方法的 Wifi Direct Api，但由于某种原因，discoverPeers 方法没有被触发。

这是我的 MainActivity 的代码：

public class MainActivity extends AppCompatActivity {

private static MainActivity instance;

Button btnOnOff, btnDiscover, btnSend;
ListView listView;
TextView read_msg_box, connection_status;
EditText writeMessage;

WifiManager wifiManager;
WifiP2pManager mManager;
WifiP2pManager.Channel mChannel;

BroadcastReceiver mReceiver;
IntentFilter mIntentFilter;

List<WifiP2pDevice> peers = new ArrayList<WifiP2pDevice>();
String[] deviceNameArray;
WifiP2pDevice[] deviceArray;

WifiP2pManager.PeerListListener peerListListener = new WifiP2pManager.PeerListListener() {

    @Override
    public void onPeersAvailable(WifiP2pDeviceList peerList) {
        if (!peerList.getDeviceList().equals(peers)) {
            peers.clear();
            peers.addAll(peerList.getDeviceList());

            deviceNameArray = new String[peerList.getDeviceList().size()];
            deviceArray = new WifiP2pDevice[peerList.getDeviceList().size()];

            int index = 0;
            for (WifiP2pDevice device : peerList.getDeviceList()) {
                deviceNameArray[index] = device.deviceName;
                deviceArray[index] = device;
                index++;
            }

            ArrayAdapter<String> adapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, deviceNameArray);
            listView.setAdapter(adapter);
        }

        if (peers.size() == 0) {
            Toast.makeText(getApplicationContext(), "No device Found", Toast.LENGTH_SHORT).show();
            return;
        }
    }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    initialWork();
    exqListener();
}
public static MainActivity getInstance() {
    return instance;
}


private void exqListener() {
    btnOnOff.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (wifiManager.isWifiEnabled() == true) {
                wifiManager.setWifiEnabled(false);
                btnOnOff.setText("Set To OFF ");
            } else {
                wifiManager.setWifiEnabled(true);
                btnOnOff.setText("Set To ON");
            }
        }
    });

    btnDiscover.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (ActivityCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.ACCESS_FINE_LOCATION) != 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;
            }
            mManager.discoverPeers(mChannel, new WifiP2pManager.ActionListener() {
                @Override
                public void onSuccess() {
                    connection_status.setText("Discovery Started");
                }

                @Override
                public void onFailure(int reason) {
                    connection_status.setText("Discovery Starting Failed");
                }
            });
        }
    });
}

private void initialWork() {
    btnOnOff = (Button) findViewById(R.id.onOff);
    btnDiscover = (Button) findViewById(R.id.discover);
    btnSend = (Button) findViewById(R.id.sendButton);
    read_msg_box = (TextView) findViewById(R.id.readMsg);
    connection_status = (TextView) findViewById(R.id.connectionStatus);
    writeMessage = (EditText) findViewById(R.id.writeMsg);
    listView = (ListView) findViewById(R.id.peerListView);

    wifiManager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
    mManager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);
    mChannel = mManager.initialize(this, getMainLooper(), null);

    mReceiver = new WifiDirectBroadcastReceiver(mManager, mChannel, this);
    mIntentFilter = new IntentFilter();

    mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);
    mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);
    mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
    mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
}




@Override
protected void onResume() {
    super.onResume();
    registerReceiver(mReceiver, mIntentFilter);
}

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

}

这是 WifiDirectBroadcatReceiver 之一：

public class WifiDirectBroadcastReceiver extends BroadcastReceiver {
private WifiP2pManager mManager;
private WifiP2pManager.Channel mChannel;
private AppCompatActivity mActivity;

public WifiDirectBroadcastReceiver(WifiP2pManager mManager, WifiP2pManager.Channel mChannel, AppCompatActivity mActivity) {
    this.mManager = mManager;
    this.mChannel = mChannel;
    this.mActivity = mActivity;
}

@Override
public void onReceive(Context context, Intent intent) {
    String action = intent.getAction();
    if (WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION.equals(action)) {
        int state = intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1);
        if (state == WifiP2pManager.WIFI_P2P_STATE_ENABLED) {
            Toast.makeText(context, "Wifi is ON", Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(context, "Wifi is OFF", Toast.LENGTH_SHORT).show();
        }
    } else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) {
        Toast.makeText(context, "Dkhal hnaya bro", Toast.LENGTH_SHORT).show();
        if (mManager != null) {
            if (ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_FINE_LOCATION) != 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;
            }

            mManager.requestPeers(mChannel, MainActivity.getInstance().peerListListener);

            }
    } else if(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {
        // Do something
    } else if (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)) {
        // Do something
    }
}

}

这是 AndroidManifest.xml 中的权限：

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"></uses-permission>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"></uses-permission>
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE"></uses-permission>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE"></uses-permission>
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>

根据代码，一旦我按下按钮 btnDiscover，就会有一个 textView 更改其文本，但是当我这样做时，什么也没有发生。

知道我在运行应用程序之前打开了我的位置服务，会出现什么错误？

欢迎所有其他解决这种情况的方法。

Answer 1

从 Android 11 开始，某些权限必须为 requested during runtime，无论清单中定义了什么。正如代码中的 cmets 所指出的，您应该在 MainActivity 中使用 requestPermissions 来执行此操作，并（可选）使用 onRequestPermissionsResult 对结果做出反应。