android - 每次在 android 中打开应用程序时监控互联网连接

Question

我正在按照 this question 中的建议检查设备的连接性使用以下代码:

final ConnectivityManager conMgr =  (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
final NetworkInfo activeNetwork = conMgr.getActiveNetworkInfo();
if (activeNetwork != null && activeNetwork.getState() == NetworkInfo.State.CONNECTED) {
    //notify user you are online
} else {
    //notify user you are not online
} 

我在我的主要 Activity 中有这个并且工作正常，但我现在想做的是在每次应用程序启动时检查互联网连接，有时应用程序处于某种状态然后互联网断开连接，所以当它再次打开时，它不会通过主要 Activity ，因此不会检查任何内容。

如 this question 中的建议我关注了this tutorial关于使用 BroadcastReceiver 监控互联网 Activity ，当 noConnectivity 为真时我尝试显示和 AlertDialog，但没有任何反应。

这是我的代码，使用上面提到的教程:

public class MyActivity extends Activity {

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.welcome);

    registerReceivers() ;
         (..my activity code goes here...)

}   

    private void noInternet()
    {
        Intent myIntent = new Intent(this, NoInternetActivity.class);
        startActivity(myIntent);
    }

    /*
     * method to be invoked to register the receiver
     */
    private void registerReceivers() {    
        registerReceiver(mConnReceiver, 
            new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION));
    }

    private void alert()
    {
        AlertDialog alertDialog = new AlertDialog.Builder(this).create();
        alertDialog.setTitle("internet connection");
        alertDialog.setMessage("To use this app you need intenet connection");
        alertDialog.setButton("ok", new DialogInterface.OnClickListener() {
           public void onClick(DialogInterface dialog, int which) {
              // here you can add functions
           }
        });
        alertDialog.show();
    }

    private BroadcastReceiver mConnReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            boolean noConnectivity = intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY, false);
            String reason = intent.getStringExtra(ConnectivityManager.EXTRA_REASON);
                        boolean isFailover = intent.getBooleanExtra(ConnectivityManager.EXTRA_IS_FAILOVER, false);

            NetworkInfo currentNetworkInfo = (NetworkInfo) intent.getParcelableExtra(ConnectivityManager.EXTRA_NETWORK_INFO);
            NetworkInfo otherNetworkInfo = (NetworkInfo) intent.getParcelableExtra(ConnectivityManager.EXTRA_OTHER_NETWORK_INFO);

            // do application-specific task(s) based on the current network state, such 
            // as enabling queuing of HTTP requests when currentNetworkInfo is connected etc.

            if(noConnectivity)
            {
                alert();
                noInternet();
            }

        }
    };
}

但 alert() 或 noInternet() 都没有启动。

希望你能帮帮我。谢谢

Answer 1

如果您想在每次 Activity 恢复时运行一些代码，即使它已经打开，那么覆盖并将您的检查代码放在 onResume() 中。每次 Activity 打开时都会调用它。