如何检查Android上的互联网接入?InetAddress从不超时

我得到了一个AsyncTask，应该检查对主机名的网络访问。但是doInBackground()永远不会超时。有人知道吗?

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();
    }   
}

当前回答

if(isConnected()){
                Toast.makeText(getApplication(),"Thank you",Toast.LENGTH_SHORT).show();
        }
        else{

            AlertDialog.Builder builder =
                    new AlertDialog.Builder(this, R.style.AppCompatAlertDialogStyle);
            builder.setTitle("Amar Bhat");
            builder.setMessage("Oops...You are not connected to Internet!!!");
            builder.setPositiveButton("OK", null);
            builder.setNegativeButton("Cancel", null);
            builder.show();
            //Toast.makeText(getApplication(),"You are not connected",Toast.LENGTH_SHORT).show();
        }




//And outside the class define isConnected()

 public boolean isConnected(){
        ConnectivityManager connMgr = (ConnectivityManager) getSystemService(Activity.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
        if (networkInfo != null && networkInfo.isConnected())
            return true;
        else
            return false;
    }

// In minifest add these permission
<uses-permission android:name="android.permission.INTERNET" />

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

2015-11-17 05:25:36

其他回答

检查Android网络/互联网连接状态并不复杂。下面的DetectConnection类将帮助你检查这个状态:

import android.content.Context;
import android.net.ConnectivityManager;

public class DetectConnection {
    public static boolean checkInternetConnection(Context context) {
        ConnectivityManager con_manager = (ConnectivityManager) context
                                .getSystemService(Context.CONNECTIVITY_SERVICE);

        if (con_manager.getActiveNetworkInfo() != null
            && con_manager.getActiveNetworkInfo().isAvailable()
            && con_manager.getActiveNetworkInfo().isConnected()) {
                return true;
        } else {
            return false;
        }
    }
}

详情请浏览如何检查Android网络/ Internet连接状态

2012-07-18 17:06:05

可以通过该方法检测网络可用性-

public static boolean isDeviceOnline(Context context) {
        boolean isConnectionAvail = false;
        try {
            ConnectivityManager cm = (ConnectivityManager) context
                    .getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo netInfo = cm.getActiveNetworkInfo();
            return netInfo.isConnected();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return isConnectionAvail;
    }

2015-02-04 08:21:31

这在android文档中有涉及 http://developer.android.com/training/monitoring-device-state/connectivity-monitoring.html

2015-03-16 15:42:32

使用这个Kotlin扩展:

/**
 * Check whether network is available
 *
 * @param context
 * @return Whether device is connected to Network.
 */
fun Context.isNetworkAvailable(): Boolean {
    with(getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            //Device is running on Marshmallow or later Android OS.
            with(getNetworkCapabilities(activeNetwork)) {
                return hasTransport(NetworkCapabilities.TRANSPORT_WIFI) || hasTransport(
                    NetworkCapabilities.TRANSPORT_CELLULAR
                )
            }
        } else {
            activeNetworkInfo?.let {
                // connected to the internet
                @Suppress("DEPRECATION")
                return listOf(ConnectivityManager.TYPE_WIFI, ConnectivityManager.TYPE_MOBILE).contains(it.type)
            }
        }
    }
    return false
}

2019-12-25 14:14:42

 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;
}

2018-06-21 06:49:59

如何检查Android上的互联网接入?InetAddress从不超时

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