如何列出所有 WiFi 接入点？

Question

我是 Android-Java 的新手，但我想写一个来查看我周围的所有 WIFI 接入点，就像 PC 和 Android 手机一样。 但是在调试过程中，我只能看到 AndroidWIFI（带有 PC），什么都没有（手机通过 USB 连接到 PC）。

我已经阅读了以下 SO 主题：

 Android - List wifi access points ( https://stackoverflow.com/questions/20741142/android-list-wifi-access-points )

 WiFi enabled device recognize WiFi access points? ( https://stackoverflow.com/questions/7349066/wifi-enabled-device-recognize-wifi-access-points )

 List WiFi access points ( https://stackoverflow.com/questions/4036747/list-wifi-access-points )

 How to get BSSID of all wifi access points? ( https://stackoverflow.com/questions/12460445/how-to-get-bssid-of-all-wifi-access-points )

... 还有很多...

这是我的权限：

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

这是我的代码：

 public class MainActivity extends AppCompatActivity {

 WifiManager w_WifiManager;
 List<ScanResult> w_results = new ArrayList<ScanResult>();
 int w_PERMISSIONS_REQUEST_CODE_ACCESS_COARSE_LOCATION, w_PERMISSIONS_REQUEST_CODE_ACCESS_FINE_LOCATION;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.activity_main);

     w_WifiManager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);

     registerReceiver(new BroadcastReceiver() {
                          @RequiresApi(api = Build.VERSION_CODES.M)
                          @Override
                          public void onReceive(Context c, Intent intent)
                          {
                              if (                                                  checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                                  requestPermissions(new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, w_PERMISSIONS_REQUEST_CODE_ACCESS_COARSE_LOCATION);

                              } else if (                                           checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION)   != PackageManager.PERMISSION_GRANTED) {
                                  requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION},   w_PERMISSIONS_REQUEST_CODE_ACCESS_FINE_LOCATION);
                              }
                              else {
                                  w_results = w_WifiManager.getScanResults();
                                  if ( w_results.size() <= 0 ) {
                                      Toast.makeText(c, "*** NOTHING TO DISPLAY ***", Toast.LENGTH_LONG).show();
                                  }
                                  else {
                                      Toast.makeText(c, w_results.get(0).SSID,        Toast.LENGTH_LONG).show();
                                  }
                              }
                          }
                      }
             , new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
     w_WifiManager.startScan();
 }
 }