Get SSID when WIFI is connected

问题

I'm trying to get the SSID of the WIFI network when my android device is connected to WIFI.

I've registered a BroadcastReceiver listening for android.net.wifi.supplicant.CONNECTION_CHANGE . I get the notification when WIFI is disconnected or reconnected. Unfortunately, I can't get the network's SSID.

I'm using the following code to find the SSID:

WifiManager wifiManager = (WifiManager) context.getSystemService(context.WIFI_SERVICE);
WifiInfo wifiInfo = wifiManager.getConnectionInfo();
String ssid = wifiInfo.getSSID();

Instead of the SSID, I get the string <unknown ssid> back.

These are the permissions in the manifest (I've added ACCESS_NETWORK_STATE just to check, I don't actually need it)

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

Why does this happen? How can I get the actual SSID? Is the broadcast fired to early, before the connection is established? Is there another broadcast I should listen to? I'm only interested in WIFI connections, not 3G connections.

Update: I just checked, wifiInfo.getBSSID() returns null.

回答1:

I listen for WifiManager.NETWORK_STATE_CHANGED_ACTION in a broadcast receiver

if (WifiManager.NETWORK_STATE_CHANGED_ACTION.equals (action)) {
        NetworkInfo netInfo = intent.getParcelableExtra (WifiManager.EXTRA_NETWORK_INFO);
        if (ConnectivityManager.TYPE_WIFI == netInfo.getType ()) {

I check for netInfo.isConnected (). Then I am able to use

WifiManager wifiManager = (WifiManager) getSystemService (Context.WIFI_SERVICE);
WifiInfo info = wifiManager.getConnectionInfo ();
String ssid  = info.getSSID();

UPDATE

From android 8.0 onwards we wont be getting SSID of the connected network unless GPS is turned on.

回答2:

Starting with Android 8.1 (API 27), apps must be granted the ACCESS_COARSE_LOCATION (or ACCESS_FINE_LOCATION) permission in order to obtain results from WifiInfo.getSSID() or WifiInfo.getBSSID().

This permission is also needed to obtain results from WifiManager.getConnectionInfo() and WifiManager.getScanResults() although it is not clear if this is new in 8.1 or was required previously.

Source: "BSSID/SSID can be used to deduce location, so require the same location permissions for access to these WifiInfo fields requested using WifiManager.getConnectionInfo() as for WifiManager.getScanResults()."

回答3:

If you don't want to make Broadcast Receiver then simple try

WifiManager wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
WifiInfo wifiInfo;

wifiInfo = wifiManager.getConnectionInfo();
if (wifiInfo.getSupplicantState() == SupplicantState.COMPLETED) {
    ssid = wifiInfo.getSSID();
}

Remember every time user disconnect or connect to new SSID or any wifi state change then you need to initialize WifiInfo i.e wifiInfo = wifiManager.getConnectionInfo();

回答4:

I found interesting solution to get SSID of currently connected Wifi AP. You simply need to use iterate WifiManager.getConfiguredNetworks() and find configuration with specific WifiInfo.getNetworkId()

My example

in Broadcast receiver with action WifiManager.NETWORK_STATE_CHANGED_ACTION I'm getting current connection state from intent

NetworkInfo nwInfo = intent.getParcelableExtra(WifiManager.EXTRA_NETWORK_INFO);
nwInfo.getState()

If NetworkInfo.getState is equal to NetworkInfo.State.CONNECTED then i can get current WifiInfo object

WifiManager wifiManager = (WifiManager) getSystemService (Context.WIFI_SERVICE);
WifiInfo info = wifiManager.getConnectionInfo ();

And after that

public String findSSIDForWifiInfo(WifiManager manager, WifiInfo wifiInfo) {

    List<WifiConfiguration> listOfConfigurations = manager.getConfiguredNetworks();

    for (int index = 0; index < listOfConfigurations.size(); index++) {
        WifiConfiguration configuration = listOfConfigurations.get(index);
        if (configuration.networkId == wifiInfo.getNetworkId()) {
            return configuration.SSID;
        }
    }

    return null;
}

And very important thing this method doesn't require Location nor Location Permisions

回答5:

In Android 8.1 it is must to turned Location on to get SSID, if not you can get connection state but not SSID

WifiManager wifiManager = (WifiManager) context.getApplicationContext().getSystemService(Context.WIFI_SERVICE);
WifiInfo wifiInfo = null;
if (wifiManager != null) 
wifiInfo = wifiManager.getConnectionInfo();
 String ssid = null;
if (wifiInfo != null) 
ssid = wifiInfo.getSSID(); /*you will get SSID <unknown ssid> if location turned off*/

回答6:

This is a follow up to the answer given by @EricWoodruff.

You could use netInfo's getExtraInfo() to get wifi SSID.

if (WifiManager.NETWORK_STATE_CHANGED_ACTION.equals (action)) {
    NetworkInfo netInfo = intent.getParcelableExtra (WifiManager.EXTRA_NETWORK_INFO);
    if (ConnectivityManager.TYPE_WIFI == netInfo.getType ()) {
        String ssid = info.getExtraInfo()
        Log.d(TAG, "WiFi SSID: " + ssid)
    }
}

If you are not using BroadcastReceiver check this answer to get SSID using Context

This is tested on Android Oreo 8.1.0

回答7:

Android 9 SSID showing NULL values use this code..

ConnectivityManager connManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = connManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
        if (networkInfo.isConnected()) {
            WifiManager wifiManager = (WifiManager) context.getApplicationContext().getSystemService(Context.WIFI_SERVICE);
            WifiInfo wifiInfo = wifiManager.getConnectionInfo();
            wifiInfo.getSSID();
            String name = networkInfo.getExtraInfo();
            String ssid = wifiInfo.getSSID();
            return ssid.replaceAll("^\"|\"$", "");
        }

来源：https://stackoverflow.com/questions/21391395/get-ssid-when-wifi-is-connected

标签

android

wifi

ssid