java - 如何从 BroadcastReceiver 内部打开 Wifi 设置

Question

我正在开发一个 Android 应用程序，它可以识别设备是否连接到网络。如果没有，应用程序将显示一个 AlertDialog 并让用户有机会转到设备设置并打开 wifi。

我已经为这项工作创建了一个BroadcastReceiver，但我不知道如何创建一个AlertDialog并为用户提供启用wifi的选项。

这是BroadcastReceiver的代码。

public class ExampleBroadcastReceiver extends BroadcastReceiver {

@Override
public void onReceive(final Context context, Intent intent) {
    if (ConnectivityManager.CONNECTIVITY_ACTION.equals(intent.getAction())) {
        boolean noConnectivity = intent.getBooleanExtra(
                ConnectivityManager.EXTRA_NO_CONNECTIVITY, false
        );
        if (noConnectivity) {
            AlertDialog.Builder builder1 = new AlertDialog.Builder(context);
            builder1.setMessage("You must have internet connection");
            builder1.setCancelable(true);

            builder1.setPositiveButton(
                    "Yes",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {

                        }
                    });

            builder1.setNegativeButton(
                    "No",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            dialog.cancel();
                        }
                    });
            builder1.create();
            builder1.show();

        } else {
            Toast.makeText(context, "Connected", Toast.LENGTH_SHORT).show();
        }
    }
}

}

Answer 1

请注意，以下代码仅供您引用。您可以根据您的要求更新/更改此代码。

public class MainActivity extends AppCompatActivity {

    private static final String TAG = MainActivity.class.getSimpleName();
    private BroadcastReceiver mNetworkReceiver;



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        registerNetworkBroadcastForNougat();

    }

private void registerNetworkBroadcastForNougat() {
    mNetworkReceiver = new NetworkChangeReceiver();
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        registerReceiver(mNetworkReceiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
    }
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        registerReceiver(mNetworkReceiver, new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
    }
}

protected void unregisterNetworkChanges() {
    try {
        unregisterReceiver(mNetworkReceiver);
    } catch (IllegalArgumentException e) {
        e.printStackTrace();
    }
}

@Override
public void onDestroy() {
    super.onDestroy();
    unregisterNetworkChanges();
}



class NetworkChangeReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent)
    {
        try
        {
            if (!isOnline(context)) {
                showDialog(context);
            }

        } catch (NullPointerException e) {
            e.printStackTrace();
        }
    }

    private void showDialog(final Context context) {
        AlertDialog.Builder builder1 = new AlertDialog.Builder(context);
        builder1.setMessage("You must have internet connection");
        builder1.setCancelable(true);

        builder1.setPositiveButton(
                "Yes",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        startActivity(new Intent(WifiManager.ACTION_PICK_WIFI_NETWORK));
                    }
                });

        builder1.setNegativeButton(
                "No",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        dialog.cancel();
                    }
                });
        builder1.create();
        builder1.show();
    }

    private boolean isOnline(Context context) {
        try {
            ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo netInfo = cm.getActiveNetworkInfo();
            //should check null because in airplane mode it will be null
            return (netInfo != null && netInfo.isConnected());
        } catch (NullPointerException e) {
            e.printStackTrace();
            return false;
        }
    }
}

}