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();
}
}
移动设备上的一个重要用例是确保存在实际连接。当移动用户使用“专属门户”进入Wifi网络时,这是一个常见的问题,他们需要在其中登录。我在后台使用这个阻塞功能来确保连接存在。
/*
* Not Thread safe. Blocking thread. Returns true if it
* can connect to URL, false and exception is logged.
*/
public boolean checkConnectionHttps(String url){
boolean responded = false;
HttpGet requestTest = new HttpGet(url);
HttpParams params = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(params, 3000);
HttpConnectionParams.setSoTimeout(params, 5000);
DefaultHttpClient client = new DefaultHttpClient(params);
try {
client.execute(requestTest);
responded = true;
} catch (ClientProtocolException e) {
Log.w(MainActivity.TAG,"Unable to connect to " + url + " " + e.toString());
} catch (IOException e) {
Log.w(MainActivity.TAG,"Unable to connect to " + url + " " + e.toString());
e.printStackTrace();
}
return responded;
}
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
}
芬兰湾的科特林实现
/**
* Function that uses ping, takes server name or ip as argument.
*
* @return [Double.MAX_VALUE] if server is not reachable. Average RTT if the server is reachable.
*
* Success output example
*
* PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
* 64 bytes from 8.8.8.8: icmp_seq=1 ttl=254 time=172 ms
* 64 bytes from 8.8.8.8: icmp_seq=2 ttl=254 time=166 ms
* 64 bytes from 8.8.8.8: icmp_seq=3 ttl=254 time=167 ms
* 64 bytes from 8.8.8.8: icmp_seq=4 ttl=254 time=172 ms
* 64 bytes from 8.8.8.8: icmp_seq=5 ttl=254 time=167 ms
* --- 8.8.8.8 ping statistics ---
* 5 packets transmitted, 5 received, 0% packet loss, time 4011ms
* rtt min/avg/max/mdev = 166.470/169.313/172.322/2.539 ms
* |________________________|
* value to parse using it.split('=')[1].trim().split(' ')[0].trim().split('/')[1].toDouble()
*/
@ExperimentalStdlibApi
fun pingServerAverageRtt(host: String): Double {
var aveRtt: Double = Double.MAX_VALUE
try {
// execute the command on the environment interface, timeout is set as 0.2 to get response faster.
val pingProcess: Process = Runtime.getRuntime().exec("/system/bin/ping -i 0.2 -c 5 $host")
// gets the input stream to get the output of the executed command
val bufferedReader = BufferedReader(InputStreamReader(pingProcess.inputStream))
bufferedReader.forEachLine {
if (it.isNotEmpty() && it.contains("min/avg/max/mdev")) { // when we get to the last line of executed ping command
aveRtt = it.split('=')[1].trim()
.split(' ')[0].trim()
.split('/')[1].toDouble()
}
}
} catch (e: IOException) {
e.printStackTrace()
}
return aveRtt
}
使用的例子
val latency = pingServerAverageRtt(ipString)
if (latency != Double.MAX_VALUE) {
//server reachable
} else {
//server not reachable
}
这是最简单和简单的方法来检查互联网连接的wifi和移动数据。
public static boolean isConnected(Activity _context) {
if (_context != null) {
ConnectivityManager connMgr = (ConnectivityManager) _context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeInfo = connMgr.getActiveNetworkInfo();
if (activeInfo != null && activeInfo.isConnected()) {
boolean wifiConnected = activeInfo.getType() == ConnectivityManager.TYPE_WIFI;
boolean mobileConnected = activeInfo.getType() == ConnectivityManager.TYPE_MOBILE;
if (wifiConnected || mobileConnected) {
Log.d(TAG, "Wifi Connected ");
return true;
} else {
showAlert(_context,_context.getString(R.string.err_no_internet));
return false;
}
} else {
showAlert(_context,_context.getString(R.string.err_no_internet));
return false;
}
} else {
Log.e(TAG, "networkConnectivity: Context NULL");
}
return false;
}
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
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。