Android Wifi Direct 检测到对等点，但对等点列表为空答案

【问题标题】：Android Wifi Direct detects peers but Peer List is emptyAndroid Wifi Direct 检测到对等点，但对等点列表为空
【发布时间】：2015-06-04 20:34:56
【问题描述】：

一切正常，但是当WifiP2pManager 调用onPeersAvailable 方法（它正确调用它）时，Peers Device List 是空的，这是没有意义的，因为如果调用该方法，那是因为发现了对等点。 :S

我的代码有问题吗？谢谢。

主要活动、广播接收器和发现：

public class Main extends Activity{

FileManager flManager;
Context ctx;
LinearLayout lay_found_users;
LinearLayout lay_conversations;
AddLayoutItem addLayoutItem = new AddLayoutItem();
private final String TAG = "Main";

//Wifi Direct
WifiP2pManager mManager;
WifiP2pManager.Channel mChannel;
BroadcastReceiver mReceiver;
IntentFilter mIntentFilter;

WifiP2pManager.PeerListListener mPeerListListener;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.act_main);
    ctx = getApplicationContext();
    flManager = new FileManager(ctx);

    //Wifi Direct
    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);

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

    mPeerListListener = new WifiP2pManager.PeerListListener(){
        @Override
        public void onPeersAvailable(WifiP2pDeviceList peerList){
            Log.i(TAG, "Peers available");
            int size = peerList.getDeviceList().size();
            Log.i(TAG, String.valueOf(size));

        }
    };

    mReceiver = new WDBroadcastReceiver(mManager, mChannel, this, mPeerListListener);
    WDDiscovery wdDiscovery = new WDDiscovery(mManager, mChannel);
    wdDiscovery.discover();
}

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

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

public class WDBroadcastReceiver extends BroadcastReceiver {

private WifiP2pManager mManager;
private WifiP2pManager.Channel mChannel;
private Main mActivity;
private final String TAG = this.getClass().getSimpleName();
private WifiP2pManager.PeerListListener mPeerListListener;

public WDBroadcastReceiver(WifiP2pManager manager, WifiP2pManager.Channel channel, Main activity, WifiP2pManager.PeerListListener peerListListener){
    super();
    this.mManager = manager;
    this.mChannel = channel;
    this.mActivity = activity;
    this.mPeerListListener = peerListListener;
}

@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){
            Log.i(TAG, "Wifi P2P Enabled");
        } else {
            Log.i(TAG, "Wifi P2P Disabled");
        }

    }else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)){
        if (mManager != null){
            mManager.requestPeers(mChannel, mPeerListListener);
            Log.i(TAG, "Peer Discovered");
        }
    }else if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)){
        // Respond to new connection or disconnections
    }else if (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)){
        // Respond to this device's wifi state changing
    }
}
}

public class WDDiscovery {

    WifiP2pManager mManager;
    WifiP2pManager.Channel mChannel;
    private final String TAG = this.getClass().getSimpleName();

    public WDDiscovery(WifiP2pManager manager, WifiP2pManager.Channel channel) {
        mManager = manager;
        mChannel = channel;
    }

    public void discover() {

        mManager.discoverPeers(mChannel, new WifiP2pManager.ActionListener() {
            @Override
            public void onSuccess() {
                Log.i(TAG, "WiFi P2P Discovery successful");
            }

            @Override
            public void onFailure(int reasonCode) {
                Log.i(TAG, "WiFi P2P Discovery error");
            }
        });
    }
}

【问题讨论】：

你用什么作为你的ListView/Adapter？我没有看到与ListViewhere 相关的代码。
我还没有使用适配器。 WifiP2pManager 调用 public void onPeersAvailable(WifiP2pDeviceList peerList){ 但 peerList 是空的
尝试在回调调用处添加断点。在调用之前、期间和之后查看您为 peerList 获得的值。
这里有一些有用的信息我认为可能对你有帮助：stackoverflow.com/questions/12729814/…
我做到了，“解决方案”正是我正在做的事情，但是尽管 BroadcastListener 检测到对等点，但对等点列表始终为空。

标签： java android wifi p2p

【解决方案1】：

就我而言，我添加

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

在清单中并授予应用权限。它有效。

【讨论】：

【解决方案2】：

我遇到了同样的问题，我的解决方案是

将这两行添加到 Android Manifiest 中

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

并确保请求该位置的运行时权限

【讨论】：