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

不要检查WIFI连接或移动数据连接,试着点击任何托管域。以便您可以检查WIFI/Mobile连接是否具有连接公共互联网的能力。

如果您的移动设备能够连接到所提供的公共域,则将返回以下内容。

boolean isReachable()
        {
            boolean connected = false;
            String instanceURL = "Your trusted domain name";
            Socket socket;
            try {
                socket = new Socket();
                SocketAddress socketAddress = new InetSocketAddress(instanceURL, 80);
                socket.connect(socketAddress, 5000);
                if (socket.isConnected()) {
                    connected = true;
                    socket.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                socket = null;
            }
            return connected;
        }

希望对大家有所帮助。

其他回答

下面是我使用的方法:

public boolean isNetworkAvailable(final Context context) {
    return ((ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE)).getActiveNetworkInfo() != null;
}

更好的是,检查确保它是“连接”的:

public boolean isNetworkAvailable(final Context context) {
    final ConnectivityManager connectivityManager = ((ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE));
    return connectivityManager.getActiveNetworkInfo() != null && connectivityManager.getActiveNetworkInfo().isConnected();
}

下面是如何使用该方法:

if (isNetworkAvailable(context)) {
    // code here
} else {
    // code
}

需要许可:

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

https://stackoverflow.com/a/16124915/950427

在芬兰湾的科特林:

class UtilityMethods {
companion object {
    fun isConnected(activity: Activity): Boolean {
        val connectivityManager: ConnectivityManager =
                activity.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        return null != connectivityManager.activeNetworkInfo
    }
}}

在Activity类中调用isConnected如下:

UtilityMethods.isConnected(this)

内部片段类如下:

UtilityMethods.isConnected(activity)
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" />
public static boolean isNetworkAvailable(Context ctx) {
ConnectivityManager connMgr = (ConnectivityManager)ctx.getSystemService(Context.CONNECTIVITY_SERVICE);
if(connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI).isConnected() ||
    connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE).isConnected()){
        return true;
}

return false;
 } 

用户这

这对我来说确实有用:

验证网络可用性。

private Boolean isNetworkAvailable() {
ConnectivityManager connectivityManager 
      = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
return activeNetworkInfo != null && activeNetworkInfo.isConnectedOrConnecting();}

验证互联网接入:

public Boolean isOnline() {
    try {
        Process p1 = java.lang.Runtime.getRuntime().exec("ping -c 1 www.google.com");
        int returnVal = p1.waitFor();
        boolean reachable = (returnVal==0);
        return reachable;
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return false;
}