WiFiP2PManager，OnPeersAvailable，DeviceList.Count零-始终

Question

我已经苦苦挣扎了几天，一直在使用2部运行Xamarin测试应用程序的Samsung S8手机，并使用最少的WiFiP2PManager代码来发现对等实体。我已经浏览了社区论坛和文档-可以这么辛苦，肯定有我缺少的东西。

我已经检查了常见错误：

• 应用程序权限集（ACCESS_FINE_LOCATION, ACCESS_COARSE_LOCATION, ACCESS_WIFI_STATE, CHANGE_WIFI_STATE, CHANGE_NETWORK_STATE, INTERNET）
• WiFi直接打开了吗？>
• 两个电话都处于发现模式（或不是，结果相同）

仍然，使用设备列表的空集合调用OnPeersAvailable。

在调试窗口中的调用顺序原来是：

1. WifiP2pManager.Initialize
2. MainActivity.RegisterReceiver
3. WifiP2pManager.DiscoverPeers
4. WifiP2pManager.RequestPeers
5. OnPeersAvailable（DeviceList.Count == 0）

这是我的代码，也许您可​​以看到一些内容？

using System;

using Android.App;
using Android.OS;
using Android.Support.V7.App;
using Android.Runtime;
using Android.Net.Wifi.P2p;
using Android.Content;
using static Android.Net.Wifi.P2p.WifiP2pManager;

namespace WiFiDirectTest
{
    [Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]
    public class MainActivity : AppCompatActivity, IChannelListener, IPeerListListener
    {
        private WifiP2pManager manager;
        Channel channel;
        MyBroadcastReceiver receiver;

        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);

            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            SetContentView(Resource.Layout.activity_main);

            System.Diagnostics.Debug.WriteLine($"Wifi - initialize");
            manager = (WifiP2pManager)GetSystemService(WifiP2pService);
            channel = manager.Initialize(this, MainLooper, null);
        }


        protected override void OnResume()
        {
            base.OnResume();

            System.Diagnostics.Debug.WriteLine($"Wifi - register receiver");
            receiver = new MyBroadcastReceiver(manager, channel, this);
            receiver.Register(this);

            System.Diagnostics.Debug.WriteLine($"Wifi - discover peers");
            manager.DiscoverPeers(channel, new MyActionListner());
        }


        protected override void OnPause()
        {
            base.OnPause();

            System.Diagnostics.Debug.WriteLine($"Wifi - unregister receiver");
            receiver.Unregister(this);
            receiver = null;
        }

        public void OnPeersAvailable(WifiP2pDeviceList peers)
        {
            var count = peers.DeviceList.Count;
            System.Diagnostics.Debug.WriteLine($"Wifi - peers available: {count}");
        }

        public void OnChannelDisconnected()
        {
            System.Diagnostics.Debug.WriteLine("OnChannelDisconnected");
        }

        private class MyActionListner : Java.Lang.Object, WifiP2pManager.IActionListener
        {
            public MyActionListner()
            {
            }

            public void OnFailure(WifiP2pFailureReason reason)
            {
                // breakpoint placed here, never reached.
            }

            public void OnSuccess()
            {
            }
        }
    }


    public class MyBroadcastReceiver : BroadcastReceiver
    {
        WifiP2pManager manager;
        WifiP2pManager.Channel channel;
        MainActivity activity;

        public MyBroadcastReceiver(WifiP2pManager manager, Channel channel, MainActivity activity)
        {
            this.manager = manager;
            this.channel = channel;
            this.activity = activity;
        }

        public void Register(MainActivity context)
        {
            var intentFilter = new IntentFilter();

            intentFilter.AddAction(WifiP2pManager.WifiP2pStateChangedAction);
            intentFilter.AddAction(WifiP2pManager.WifiP2pPeersChangedAction);
            intentFilter.AddAction(WifiP2pManager.WifiP2pConnectionChangedAction);
            intentFilter.AddAction(WifiP2pManager.WifiP2pThisDeviceChangedAction);

            context.RegisterReceiver(this, intentFilter);
        }

        public void Unregister(MainActivity context)
        {
            context.UnregisterReceiver(this);
        }

        public override void OnReceive(Context context, Intent intent)
        {
            var action = intent.Action;

            if (WifiP2pManager.WifiP2pStateChangedAction.Equals(action))
            {
                 System.Diagnostics.Debug.WriteLine("WifiP2pStateChangedAction");
            }
            else if (WifiP2pManager.WifiP2pPeersChangedAction.Equals(action))
            {
                System.Diagnostics.Debug.WriteLine($"Wifi - request peers");
                manager.RequestPeers(channel, activity);
            }
            else if (WifiP2pManager.WifiP2pConnectionChangedAction.Equals(action))
            {
                System.Diagnostics.Debug.WriteLine("WifiP2pConnectionChangedAction");
            }
            else if (WifiP2pManager.WifiP2pThisDeviceChangedAction.Equals(action))
            {
                System.Diagnostics.Debug.WriteLine("WifiP2pThisDeviceChangedAction");
            }
        }
    }
}
有什么想法吗？

-约翰

我已经苦苦挣扎了几天，一直在使用2部运行Xamarin测试应用程序的Samsung S8手机，并使用最少的WiFiP2PManager代码来发现对等实体。我浏览了社区论坛，然后...

Answer 1

您可以将设备列表复制到列表中并在其上应用size（）（请参见下文，其中peers_list是列表）