I am developping an application for my android phone, and I am trying to enable the Wifi hotspot. I am using Qt 5.4.1 so I developp in C++. As there is not any function to do this in the NDK, I am using JNI to call Java Methods.
My java code is (thanks to Ashish Sahu's answer in stackoverflow thread) :
package org.app.test;
import android.content.*;
import android.net.wifi.*;
import java.lang.reflect.*;
//Class that handles Wifi Hotspot (access point) configuration
public class ApManager {
//Is Wifi hotspot on or off ?
public static boolean isApOn(Context context) {
WifiManager wifimanager = (WifiManager) context.getSystemService(context.WIFI_SERVICE);
try {
Method method = wifimanager.getClass().getDeclaredMethod("isWifiApEnabled");
method.setAccessible(true);
return (Boolean) method.invoke(wifimanager);
}
catch (Throwable ignored) {}
return false;
}
//Turn Wifi hotspot on or off
public static boolean configApState(Context context, boolean b) {
WifiManager wifimanager = (WifiManager) context.getSystemService(context.WIFI_SERVICE);
WifiConfiguration wificonfiguration = null;
try {
//if Wifi is on, turn it off
if(isApOn(context)) {
wifimanager.setWifiEnabled(false);
}
Method method = wifimanager.getClass().getMethod("setWifiApEnabled", WifiConfiguration.class, boolean.class);
method.invoke(wifimanager, wificonfiguration, b);
return true;
}
catch(Exception e) {
e.printStackTrace();
}
return false;
}
}
C++ code sample :
setWifiApEnabled(QAndroidJniObject context, bool b)
{
return QAndroidJniObject::callStaticMethod<jboolean>("org/app/test/ApManager"
, "configApState"
, "(Ljava/lang/Object;Z)Z" //Or (Landroid/content/Context;Z)Z ???
, context.object<jobject>()
, b);
}
But now I have a problem ; how to get the parameter context
to pass to the function setWifiApEnabled(context, b)
when I call it ?
I am a little lost, I read some threads about this problem (like this one) but I do not totally understand what the people who answered meant.
Could you help me with this ?
EDIT : I found on this stackoverflow thread a way to get the context :
interface = QApplication::platformNativeInterface();
activiti = (jobject)interface->nativeResourceForIntegration("QtActivity");
at = new QAndroidJniObject(activiti);
appctx = at->callObjectMethod("getApplicationContext", "()Landroid/content/Context;");
if(appctx.isValid()) qDebug() << "I am valid !";
else qDebug() << "I ain't valid !";
appctx
is valid, but the Wifi hotspot doesn't get enabled and I cannot get its state.
EDIT 2 : : I successfully managed to enable the Wifi hotspot in java, using Android Studio. The code is the following :
WifiApManager.java :
public class WifiApManager {
private WifiManager wifiMan;
protected Method setWifiApEnabledMethod, isWifiApEnabledMethod;
protected final static int MAX_ITER = 10;
public WifiApManager(WifiManager wifiMan) {
this.wifiMan = wifiMan;
getHiddenMethods();
}
private void getHiddenMethods() {
try {
setWifiApEnabledMethod = wifiMan.getClass().getMethod("setWifiApEnabled", WifiConfiguration.class, boolean.class);
isWifiApEnabledMethod = wifiMan.getClass().getMethod("isWifiApEnabled");
} catch (NoSuchMethodException e) {
e.printStackTrace();
}
}
public boolean isWifiApEnabled() {
try {
return (Boolean)isWifiApEnabledMethod.invoke(wifiMan);
} catch (Exception e) {
return false;
}
}
public boolean isWifiEnabled() {
return wifiMan.isWifiEnabled();
}
public boolean setWifiApEnabled(WifiConfiguration conf, boolean enabled) {
try {
return (Boolean) setWifiApEnabledMethod.invoke(wifiMan, conf, true);
} catch (Exception e) {
return false;
}
}
public boolean toggleWifi(String ssid) {
// WifiConfiguration creation:
WifiConfiguration conf = new WifiConfiguration();
conf.SSID = ssid;
conf.allowedAuthAlgorithms.set(WifiConfiguration.AuthAlgorithm.OPEN);
// If AP Wifi is enabled, disables it and returns:
if(isWifiApEnabled()) {
//setWifiApEnabled(null, false); Won't work, see two further lines
wifiMan.setWifiEnabled(true);
wifiMan.setWifiEnabled(false);
int maxIter = MAX_ITER;
while (isWifiApEnabled() && maxIter-- >= 0) {
try {Thread.sleep(500);} catch (Exception e) {}
}
return isWifiApEnabled();
}
// If standard Wifi is enabled, disables it:
if (isWifiEnabled()) {
if (wifiMan.setWifiEnabled(false)) {
int maxIter = MAX_ITER;
while (wifiMan.isWifiEnabled() && maxIter-- >= 0) {
try {Thread.sleep(500);} catch (Exception e) {}
}
}
if (isWifiEnabled()) {
return false;
}
}
// Enables AP Wifi
try {
if (! setWifiApEnabled(conf, true)) {
System.out.println("setWifiApEnabledMethod failed.");
return false;
}
int maxIter = MAX_ITER;
while (! isWifiApEnabled() && maxIter-- > 0) {
try {Thread.sleep(500);} catch (Exception e) {}
}
} catch(Exception e) {
e.printStackTrace();
return false;
}
return true;
}
}
Main class :
public class AndroidMenusActivity extends Activity implements OnClickListener {
private WifiApManager wifiMan;
private ToggleButton wifiButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
wifiMan = new WifiApManager((WifiManager) this.getSystemService(Context.WIFI_SERVICE));
setContentView(R.layout.activity_android_menus);
makeUI();
}
private void makeUI() {
LinearLayout subLayout = (LinearLayout) findViewById(R.id.subLayout);
wifiButton = new ToggleButton(this);
wifiButton.setTextOn("Disable Wifi");
wifiButton.setTextOff("Enable AP Wifi");
wifiButton.setChecked(wifiMan.isWifiApEnabled());
wifiButton.setOnClickListener(this);
subLayout.addView(wifiButton);
}
@Override
public void onClick(View sender) {
if (!wifiButton.equals(sender))
return;
AsyncTask<Object, Void, Boolean> task = new AsyncTask<Object, Void, Boolean>() {
private ToggleButton bt;
private WifiApManager wm;
@Override
protected Boolean doInBackground(Object... args) {
bt = (ToggleButton) args[0];
wm = (WifiApManager) args[1];
return wm.toggleWifi("test.com");
}
@Override
protected void onPostExecute (Boolean result) {
bt.setChecked(result.booleanValue());
bt.setEnabled(true);
}
};
wifiButton.setEnabled(false);
task.execute(wifiButton, wifiMan);
}
}
But I cannot find a way to do the same in C++, any help ?
Just in order to transfer context object from C++ to JNI, use auto-injection like that: