Wie prüft man den Internetzugang auf Android? InetAddress schaltet nie ab

Question

Ich habe eine AsyncTask das den Netzzugang zu einem Hostnamen überprüfen soll. Aber die doInBackground() ist nie zeitlich begrenzt. Hat jemand einen Hinweis?

public class HostAvailabilityTask extends AsyncTask<String, Void, Boolean> {

    private Main main;

    public HostAvailabilityTask(Main main) {
        this.main = main;
    }

    protected Boolean doInBackground(String... params) {
        Main.Log("doInBackground() isHostAvailable():"+params[0]);

        try {
            return InetAddress.getByName(params[0]).isReachable(30); 
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return false;       
    }

    protected void onPostExecute(Boolean... result) {
        Main.Log("onPostExecute()");

        if(result[0] == false) {
            main.setContentView(R.layout.splash);
            return;
        }

        main.continueAfterHostCheck();
    }   
}

Answer 1

Methode verwenden:

private fun isInternetAvailable(context: Context): Boolean {
    (context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager).run {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            return this.getNetworkCapabilities(this.activeNetwork)?.hasCapability(
                NetworkCapabilities.NET_CAPABILITY_INTERNET
            ) ?: false
        } else {
            (@Suppress("DEPRECATION")
            return this.activeNetworkInfo?.isConnected ?: false)
        }
    }
}

Und die erforderlichen Genehmigungen:

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

Answer 2

Wenn Sie Firebase verwenden, können Sie diese .

Java:

DatabaseReference connectedRef = FirebaseDatabase.getInstance().getReference(".info/connected");
connectedRef.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot snapshot) {
        boolean connected = snapshot.getValue(Boolean.class);
        if (connected) {
            Log.d(TAG, "connected");
        } else {
            Log.d(TAG, "not connected");
        }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError error) {
        Log.w(TAG, "Listener was cancelled");
    }
});

Kotlin:

val connectedRef = Firebase.database.getReference(".info/connected")
connectedRef.addValueEventListener(object : ValueEventListener {
    override fun onDataChange(snapshot: DataSnapshot) {
        val connected = snapshot.getValue(Boolean::class.java) ?: false
        if (connected) {
            Log.d(TAG, "connected")
        } else {
            Log.d(TAG, "not connected")
        }
    }

    override fun onCancelled(error: DatabaseError) {
        Log.w(TAG, "Listener was cancelled")
    }
})

Answer 3

 public static boolean isNetworkAvailable(Context context) {
    boolean flag = checkNetworkAvailable(context);

    if (!flag) {
        Log.d("", "No network available!");
    } 
    return flag;
}

private static boolean checkNetworkAvailable(Context context) {
    ConnectivityManager connectivityManager
            = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
    return activeNetworkInfo != null;
}

Answer 4

Dies ist der einfachste und leichteste Weg, um die Internetverbindung für WLAN und mobile Daten zu überprüfen.

public static boolean isConnected(Activity _context) {
        if (_context != null) {
            ConnectivityManager connMgr = (ConnectivityManager) _context.getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo activeInfo = connMgr.getActiveNetworkInfo();
            if (activeInfo != null && activeInfo.isConnected()) {
                boolean wifiConnected = activeInfo.getType() == ConnectivityManager.TYPE_WIFI;
                boolean mobileConnected = activeInfo.getType() == ConnectivityManager.TYPE_MOBILE;

                if (wifiConnected || mobileConnected) {
                    Log.d(TAG, "Wifi Connected ");
                    return true;
                } else {
                    showAlert(_context,_context.getString(R.string.err_no_internet));
                    return false;
                }
            } else {
                showAlert(_context,_context.getString(R.string.err_no_internet));
                return false;
            }
        } else {
            Log.e(TAG, "networkConnectivity: Context NULL");

        }
        return false;
    }

Answer 5

Mit diesem Code können Sie feststellen, ob das Internet eingeschaltet ist oder nicht.

public final boolean isInternetOn() {
        ConnectivityManager conMgr = (ConnectivityManager) this.con
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo info = conMgr.getActiveNetworkInfo();
        return (info != null && info.isConnected());
}

Außerdem sollten Sie die folgenden Berechtigungen vergeben

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