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();
}
}
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
在我目前所见过的所有方法中，最短、最干净的方法应该是:
public final static boolean isConnected( Context context )
{
final ConnectivityManager connectivityManager =
(ConnectivityManager) context.getSystemService( Context.CONNECTIVITY_SERVICE );
final NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
return networkInfo != null && networkInfo.isConnected();
}
PS:这不会ping任何主机，它只是检查连接状态，所以如果你的路由器没有互联网连接，而你的设备连接到它，这个方法将返回true，尽管你没有互联网。
对于实际的测试，我建议执行一个HttpHead请求(例如到www.google.com)并检查状态，如果它是200 OK，一切正常，并且您的设备有互联网连接。
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
