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

正如Android文档建议的那样,之后

getActiveNetworkInfo()在Android 10中已弃用。使用 而不是针对Android 10 (API级别)的应用程序的NetworkCallbacks 29)更高。

下面是我们目前检查网络连接的方法:

val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
val activeNetwork: NetworkInfo? = cm.activeNetworkInfo
val isConnected: Boolean = activeNetwork?.isConnectedOrConnecting == true

使用NetworkCallbacks检查网络连接的新方法

步骤1:

    private lateinit var connectivityManager:ConnectivityManager

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        ...
        connectivityManager = getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
    }

步骤2:创建回调:

private val callback = object : ConnectivityManager.NetworkCallback() {
    override fun onAvailable(network: Network) {
        super.onAvailable(network)
        Timber.e("Network:onAvailable")
    }

    override fun onLost(network: Network) {
        super.onLost(network)
        Timber.e("Network:onLost")
    }

}

步骤3:注册和取消注册回调:

private fun registerNetworkCallback() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        connectivityManager.registerDefaultNetworkCallback(callback)
    } else {
        // Old way to check network connection
    }
}

override fun onStop() {
    unRegisterNetworkCallback()
    super.onStop()
}

private fun unRegisterNetworkCallback() {
    connectivityManager.unregisterNetworkCallback(callback)
}

结帐更新详情如下链接:

https://developer.android.com/training/monitoring-device-state/connectivity-status-type

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

我已经应用了@Levit提供的解决方案,并创建了不会调用额外Http请求的函数。

它将解决无法解析主机的错误

public static boolean isInternetAvailable(Context context) {
    ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
    if (activeNetwork == null) return false;

    switch (activeNetwork.getType()) {
        case ConnectivityManager.TYPE_WIFI:
            if ((activeNetwork.getState() == NetworkInfo.State.CONNECTED ||
                    activeNetwork.getState() == NetworkInfo.State.CONNECTING) &&
                    isInternet())
                return true;
            break;
        case ConnectivityManager.TYPE_MOBILE:
            if ((activeNetwork.getState() == NetworkInfo.State.CONNECTED ||
                    activeNetwork.getState() == NetworkInfo.State.CONNECTING) &&
                    isInternet())
                return true;
            break;
        default:
            return false;
    }
    return false;
}

private static boolean isInternet() {

    Runtime runtime = Runtime.getRuntime();
    try {
        Process ipProcess = runtime.exec("/system/bin/ping -c 1 8.8.8.8");
        int exitValue = ipProcess.waitFor();
        Debug.i(exitValue + "");
        return (exitValue == 0);
    } catch (IOException | InterruptedException e) {
        e.printStackTrace();
    }

    return false;
}

现在叫它,

if (!isInternetAvailable(getActivity())) {
     //Show message
} else {
     //Perfoem the api request
}

要让getActiveNetworkInfo()工作,您需要向清单中添加以下内容。

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

这里有一个简单的解决方案,以确保你的应用程序可以访问互联网:

static final String CHECK_INTERNET_ACCESS_URL = "https://www.google.com";

public static void isInternetAccessWorking(Context context) {

    StringRequest stringRequest = new StringRequest(Request.Method.GET, CHECK_INTERNET_ACCESS_URL,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    // Internet access is OK
                }
            }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            // NO internet access
        }
    });

    Volley.newRequestQueue(context).add(stringRequest);
}

这个解决方案使用Android的Volley库,必须在build.gradle中声明:

implementation 'com.android.volley:volley:1.1.1'

我使用这段代码而不是InetAddress:

    try {

        URL url = new URL("http://"+params[0]);

        HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
        urlc.setRequestProperty("User-Agent", "Android Application:"+Z.APP_VERSION);
        urlc.setRequestProperty("Connection", "close");
        urlc.setConnectTimeout(1000 * 30); // mTimeout is in seconds
        urlc.connect();
        if (urlc.getResponseCode() == 200) {
            Main.Log("getResponseCode == 200");
            return new Boolean(true);
        }
    } catch (MalformedURLException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }