Android - Wifi Direct / p2p 无法在 Android 8 上找到对等点

Question

我开始创建 Android 应用 wifi Wifi 直连功能。 我进行了对等发现，我喜欢在列表视图中查看对等点。

我现在有一个应用程序，它尝试发现对等点并在列表中显示对等点。

但我面临的问题是这在我的 Android 5 设备上运行良好。在这里，我可以看到我的 Android 8 设备，但反之则不行。我在我的 Android 8 设备上看不到我的 Android 5 设备。

我按照以下步骤操作： https://developer.android.com/training/connect-devices-wirelessly/nsd

还发现了这个帖子：Android O issues with WiFi Peer Discovery，上面说我需要在继续之前请求权限。

我的清单：

<uses-permission
    android:required="true"
    android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission
    android:required="true"
    android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission
    android:required="true"
    android:name="android.permission.CHANGE_WIFI_STATE"/>
<uses-permission
    android:required="true"
    android:name="android.permission.INTERNET"/>

可能是什么问题？如果需要解决问题，也许我可以提供更多信息？

Answer 1

只需打开位置信息，它对我有用

Answer 2

要在 Android 8(Oreo) 上解决上述问题，有两个步骤：
1) 授予位置权限。

    if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED){
       requestPermissions(new String[]{Manifest.permission.ACCESS_COARSE_LOCATION},
                     PERMISSIONS_REQUEST_CODE_ACCESS_COARSE_LOCATION);
        //After this point you wait for callback in onRequestPermissionsResult(int, String[], int[]) overriden method

    }else{
       mManager.requestPeers(mChannel, mainActivity.peerListListener);
       //do something, permission was previously granted; or legacy device
    }

2) 启用定位服务/打开设备的 GPS。
下面的代码打开对话框以启用位置。

public static void displayLocationSettingsRequest(final Context context, final int REQUEST_CHECK_SETTINGS) {
    GoogleApiClient googleApiClient = new GoogleApiClient.Builder(context)
            .addApi(LocationServices.API).build();
    googleApiClient.connect();

    LocationRequest locationRequest = LocationRequest.create();
    locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    locationRequest.setInterval(10000);
    locationRequest.setFastestInterval(10000 / 2);

    LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder().addLocationRequest(locationRequest);
    builder.setAlwaysShow(true);

    Task<LocationSettingsResponse> result = LocationServices.getSettingsClient(context).checkLocationSettings(builder.build());
    result.addOnCompleteListener(new OnCompleteListener<LocationSettingsResponse>() {
        @Override
        public void onComplete(@NonNull Task<LocationSettingsResponse> task) {
            LocationSettingsResponse response = null;
            try {
                response = task.getResult(ApiException.class);
            } catch (ApiException exception) {
                exception.printStackTrace();

                switch (exception.getStatusCode()) {
                    case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
                        // Location settings are not satisfied. But could be fixed by showing the
                        // user a dialog.
                        try {
                            // Cast to a resolvable exception.
                            ResolvableApiException resolvable = (ResolvableApiException) exception;
                            // Show the dialog by calling startResolutionForResult(),
                            // and check the result in onActivityResult().
                            resolvable.startResolutionForResult((MainActivity)context, REQUEST_CHECK_SETTINGS);
                            break;
                        } catch (IntentSender.SendIntentException e) {
                            // Ignore the error.
                        } catch (ClassCastException e) {
                            // Ignore, should be an impossible error.
                        }
                        break;
                    case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
                        // Location settings are not satisfied. However, we have no way to fix the
                        // settings so we won't show the dialog.

                        break;
                }
            }

        }
    });

Answer 3

我通过添加运行时权限来修复它...

Manifest.permission.ACCESS_COARSE_LOCATION

允许，一切正常