Question

我需要找到所有可用的wifi网络。这是我获取网络的代码

    public IList<ScanResult> getWifiNetworks()
    {
        _wifi = (WifiManager) _context.GetSystemService(Context.WifiService);
        return  _wifi.ScanResults;
    }

但是在_wifi.ScanResults中，我找不到所有的wifi网络。 Android清单

<uses-sdk android:minSdkVersion="24" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>

Answer 1

我写了一个有关您需求的演示。

这是我的演示的gif

首先，您应该在AndroidManifest.xml

中添加这些权限

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.CHANGE_COMPONENT_ENABLED_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS" />

并通过链接请求这些权限，我没有足够的时间来实现，所以我手动添加了它（在android设置中）。如果您不知道如何实现，可以参考以下链接，或者我如果需要，可以帮助您实现目标。 https://docs.microsoft.com/en-us/xamarin/android/app-fundamentals/permissions?tabs=windows

有一个广播接收器。

    [BroadcastReceiver]
public class WifiScanReceiver : BroadcastReceiver
{
    private MainActivity mainActivity;

    public WifiScanReceiver() { }
    public WifiScanReceiver(MainActivity mainActivity)
    {
        this.mainActivity = mainActivity;
    }

    public override async void OnReceive(Context context, Intent intent)
    {
        var mainActivity = (MainActivity)context;

        var wifiManager = (WifiManager)mainActivity.GetSystemService(Context.WifiService);
        var message = string.Join("\r\n", wifiManager.ScanResults
            .Select(r => $"{r.Ssid} - {r.Bssid}"));

        mainActivity.DisplayText(message);
        await Task.Delay(TimeSpan.FromSeconds(1));
        wifiManager.StartScan();

      //  Toast.MakeText(context, "Received intent!", ToastLength.Short).Show();

    }
}

MainActivity.cs

     [Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]
public class MainActivity : AppCompatActivity
{
    TextView txtScanResults;
    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        Xamarin.Essentials.Platform.Init(this, savedInstanceState);
        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.activity_main);

        RegisterReceiver(new WifiScanReceiver(this), new IntentFilter(WifiManager.ScanResultsAvailableAction));
        ((Android.Net.Wifi.WifiManager)GetSystemService(WifiService)).StartScan();
        txtScanResults = FindViewById<TextView>(Resource.Id.textView1);
    }
    public void DisplayText(string text)
    {
        txtScanResults.Text = "Wifi networks: \r\n" + text;
    }
    protected override void OnResume()
    {
        base.OnResume();


    }
 }

activity_main.axml

 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:orientation="vertical"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:minWidth="25px"
   android:minHeight="25px">

 <TextView
  android:text="Scanning for networks..."
  android:textAppearance="?android:attr/textAppearanceMedium"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:layout_margin="10dp"
  android:id="@+id/textView1"
  android:typeface="monospace" />
 </LinearLayout>

有我的演示。

https://github.com/851265601/ReceiverWifiDemo

为什么_wifi.ScanResults返回null，如何解决？

1 个答案: