Android comes with a complete support for the WiFi connectivity. The main component is the system-provided WiFiManager. As usual, we obtain it via getSystemServices() call to the current context.
Once we have the WiFiManager, we can ask it for the current WIFi connection in form of WiFiInfo object. We can also ask for all the currently available networks via getConfiguredNetworks(). That gives us the list of WifiConfigurations.
In this example we are also registering a broadcast receiver to perform the scan for new networks.
CODE:
public class WiFiDemo extends Activity implements OnClickListener {
private static final String TAG = "WiFiDemo";
WifiManager wifi;
BroadcastReceiver receiver;
TextView textStatus;
Button buttonScan;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Setup UI
textStatus = (TextView) findViewById(R.id.textStatus);
buttonScan = (Button) findViewById(R.id.buttonScan);
buttonScan.setOnClickListener(this);
// Setup WiFi
wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
// Get WiFi status
WifiInfo info = wifi.getConnectionInfo();
textStatus.append("\n\nWiFi Status: " + info.toString());
// List available networks
List<WifiConfiguration> configs = wifi.getConfiguredNetworks();
for (WifiConfiguration config : configs) {
textStatus.append("\n\n" + config.toString());
}
// Register Broadcast Receiver
if (receiver == null)
receiver = new WiFiScanReceiver(this);
registerReceiver(receiver, new IntentFilter(
WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
Log.d(TAG, "onCreate()");
}
@Override
public void onStop() {
unregisterReceiver(receiver);
}
public void onClick(View view) {
Toast.makeText(this, "On Click Clicked. Toast to that!!!",
Toast.LENGTH_LONG).show();
if (view.getId() == R.id.buttonScan) {
Log.d(TAG, "onClick() wifi.startScan()");
wifi.startScan();
}
}
}
The WiFiScanReceiver is registered by WiFiDemo as a broadcast receiver to be invoked by the system when new WiFi scan results are available. WiFiScanReceiver gets the callback via onReceive(). It gets the new scan result from the intent that activated it and compares it to the best known signal provider. It then outputs the new best network via a Toast.
WiFiScanReceiver.java
public class WiFiScanReceiver extends BroadcastReceiver {
private static final String TAG = "WiFiScanReceiver";
WiFiDemo wifiDemo;
public WiFiScanReceiver(WiFiDemo wifiDemo) {
super();
this.wifiDemo = wifiDemo;
}
@Override
public void onReceive(Context c, Intent intent) {
List<ScanResult> results = wifiDemo.wifi.getScanResults();
ScanResult bestSignal = null;
for (ScanResult result : results) {
if (bestSignal == null
|| WifiManager.compareSignalLevel(bestSignal.level, result.level) < 0)
bestSignal = result;
}
String message = String.format("%s networks found. %s is the strongest.",
results.size(), bestSignal.SSID);
Toast.makeText(wifiDemo, message, Toast.LENGTH_LONG).show();
Log.d(TAG, "onReceive() message: " + message);
}
}
The layout file for this example is fairly simple. It has one TextView wrapped in a ScrollView for scrolling purposes.
/res/layout/main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button android:layout_width="wrap_content"
android:layout_height="wrap_content" android:id="@+id/buttonScan"
android:text="Scan"></Button>
<ScrollView android:id="@+id/ScrollView01"
android:layout_width="wrap_content" android:layout_height="wrap_content">
<TextView android:layout_width="fill_parent"
android:layout_height="wrap_content" android:id="@+id/textStatus"
android:text="WiFiDemo" />
</ScrollView>
</LinearLayout>
For the AndroidManifest.xml file, just remember to add the permissions to use WiFi:
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
