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:

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5:

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6:

Check via NetworkInfo for wifi-type if it is connected. And then use wifiinfo getSSid(). You might want to remove double slashes from returnd SSID

https://play.google.com/store/apps/details?id=com.connect.freewifi

You should check out this application and developer api from http://developer.android.com/reference/android/net/wifi/WifiInfo.html

It will help you with your task.

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("^\"|\"$", "");
        }