Using "svc" through ADB (rooted required):

Enable:

adb shell su -c 'svc wifi enable'

Disable:

adb shell su -c 'svc wifi disable'

Using Key Events through ADB:

adb shell am start -a android.intent.action.MAIN -n com.android.settings/.wifi.WifiSettingsadb shell input keyevent 20 & adb shell input keyevent 23

The first line launch "wifi.WifiSettings" activity which open the WiFi Settings page. The second line simulate key presses.

I tested those two lines on a Droid X. But Key Events above probably need to edit in other devices because of different Settings layout.

More info about "keyevents" here.

I was searching for the same to turn bluetooth on/off, and I found this:

adb shell svc wifi enable|disable

Simple way to switch wifi on non-rooted devices is to use simple app:

public class MainActivity extends Activity {    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        WifiManager wfm = (WifiManager) getSystemService(Context.WIFI_SERVICE);        try {            wfm.setWifiEnabled(Boolean.parseBoolean(getIntent().getStringExtra("wifi")));        } catch (Exception e) {        }        System.exit(0);    }}

AndroidManifest.xml:

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

ADB commands:

$ adb shell am start -n org.mytools.config/.MainActivity -e wifi true$ adb shell am start -n org.mytools.config/.MainActivity -e wifi false