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

代码:

    fun isInternetConnection(): Boolean {
    var returnVal = false
    thread {
        returnVal = try {
            khttp.get("https://www.google.com/")
            true
        }catch (e:Exception){
            false
        }
    }.join()
    return returnVal
}

Gradle:

implementation 'io.karn:khttp-android:0.1.0'

我使用khttp是因为它很容易使用。

在上面的代码中，如果它成功连接到google.com，它返回true否则为false。很简单。我不明白为什么每个人都要写这么长的代码，即使是为了这么简单的事情。

2021-06-01 10:08:21

其他回答

以下是来自我的Utils类的代码:

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

2013-06-11 09:22:36

看一下ConnectivityManager类。您可以使用这个类来获取主机上活动连接的信息。http://developer.android.com/reference/android/net/ConnectivityManager.html

编辑:你可以使用

Context.getSystemService(Context.CONNECTIVITY_SERVICE)
    .getNetworkInfo(ConnectivityManager.TYPE_MOBILE)

Context.getSystemService(Context.CONNECTIVITY_SERVICE)
    .getNetworkInfo(ConnectivityManager.TYPE_WIFI)

并解析返回NetworkInfo对象的DetailedState枚举

EDIT EDIT:查看是否可以访问主机

Context.getSystemService(Context.CONNECTIVITY_SERVICE)
    .requestRouteToHost(TYPE_WIFI, int hostAddress)

显然，我使用Context.getSystemService(Context.CONNECTIVITY_SERVICE)作为代理来表示

ConnectivityManager cm = Context.getSystemService(Context.CONNECTIVITY_SERVICE);
cm.yourMethodCallHere();

2009-10-13 15:38:47

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

2013-10-03 10:22:57

The other answers that use ConnectivityManager are wrong because having a network connection doesn't mean you have internet access. For example, the user might be connected to a coffee shop's WiFi portal but can't get to the internet. To check that the internet is accessible you have to try to connect to an actual server. Normally when you want to do this you have a specific server in mind that you want to connect to, so go ahead and check if you can connect to that server. Here's a simple method for checking connectivity to a server.

private boolean isOnTheInternet() {
    try {
        URLConnection urlConnection = new URL("http://yourserver").openConnection();
        urlConnection.setConnectTimeout(400);
        urlConnection.connect();
        return true;
    } catch (Exception e) {
        return false;
    }
}

设置ConnectTimeout的原因是，否则它默认为TCP超时，可以有很多秒长。

还要注意的是，Android不允许你在主线程上运行这个程序。

2014-01-31 02:55:27

如果设备处于飞行模式(或者假设在没有可用网络的其他情况下)，cm.getActiveNetworkInfo()将为空，因此您需要添加一个空检查。

修改(Eddie的解决方案)如下:

public boolean isOnline() {
    ConnectivityManager cm =
        (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    return netInfo != null && netInfo.isConnectedOrConnecting();
}

在AndroidManifest.xml中添加以下权限:

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

还有一点，如果你在给定的时间点绝对需要一个网络连接，那么使用netInfo.isConnected()而不是netInfo.isConnectedOrConnecting可能会更好。不过，我想这取决于个人用例。

2010-10-24 16:28:54

如何检查Android上的互联网接入?InetAddress从不超时

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