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();
}
}
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)
更新29/06/2015
如果你正在使用Xamarin。Android和想要检查连接，你可以使用Nuget包，这将给你在多个平台上的功能。好的候选人在这里和这里。
[更新结束]
The Answers above are quite good, but they are all in Java, and almost all of them check for a connectivity. In my case, I needed to have connectivity with a specific type of connection and I am developing on Xamarin.Android. Moreover, I do not pass a reference to my activities Context in the Hardware layer, I use the Application Context. So here is my solution, in case somebody comes here with similar requirements. I have not done full testing though, will update the answer once I am done with my testing
using Android.App;
using Android.Content;
using Android.Net;
namespace Leopard.Mobile.Hal.Android
{
public class AndroidNetworkHelper
{
public static AndroidNetworkStatus GetWifiConnectivityStatus()
{
return GetConnectivityStatus(ConnectivityType.Wifi);
}
public static AndroidNetworkStatus GetMobileConnectivityStatus()
{
return GetConnectivityStatus(ConnectivityType.Mobile);
}
#region Implementation
private static AndroidNetworkStatus GetConnectivityStatus(ConnectivityType connectivityType)
{
var connectivityManager = (ConnectivityManager)Application.Context.GetSystemService(Context.ConnectivityService);
var wifiNetworkInfo = connectivityManager.GetNetworkInfo(connectivityType);
var result = GetNetworkStatus(wifiNetworkInfo);
return result;
}
private static AndroidNetworkStatus GetNetworkStatus(NetworkInfo wifiNetworkInfo)
{
var result = AndroidNetworkStatus.Unknown;
if (wifiNetworkInfo != null)
{
if (wifiNetworkInfo.IsAvailable && wifiNetworkInfo.IsConnected)
{
result = AndroidNetworkStatus.Connected;
}
else
{
result = AndroidNetworkStatus.Disconnected;
}
}
return result;
}
#endregion
}
public enum AndroidNetworkStatus
{
Connected,
Disconnected,
Unknown
}
下面是我用于可达性检查的Kotlin版本，
芬兰湾的科特林MyReachability
object MyReachability {
private val REACHABILITY_SERVER = "http://google.com" // can be any URL you want
private fun hasNetworkAvailable(context: Context): Boolean {
val service = Context.CONNECTIVITY_SERVICE
val manager = context.getSystemService(service) as ConnectivityManager?
val network = manager?.activeNetworkInfo
Log.d(classTag, "hasNetworkAvailable: ${(network != null)}")
return (network != null)
}
fun hasInternetConnected(context: Context): Boolean {
if (hasNetworkAvailable(context)) {
try {
val connection = URL(REACHABILITY_SERVER).openConnection() as HttpURLConnection
connection.setRequestProperty("User-Agent", "Test")
connection.setRequestProperty("Connection", "close")
connection.connectTimeout = 1500
connection.connect()
Log.d(classTag, "hasInternetConnected: ${(connection.responseCode == 200)}")
return (connection.responseCode == 200)
} catch (e: IOException) {
Log.e(classTag, "Error checking internet connection", e)
}
} else {
Log.w(classTag, "No network available!")
}
Log.d(classTag, "hasInternetConnected: false")
return false
}
}
您甚至可以根据策略和限制将REACHABILITY_SERVER作为参数传递，例如，当您在中国时，您可以检查https://baidu.com而不是https://google.com。
调用示例中,
val webLoaderThread = Thread {
if (MyReachability.hasInternetConnected(this)){
runOnUiThread {
//mWebView.loadUrl(LANDING_SERVER) // connected
}
} else {
runOnUiThread {
//showDialogNoNetwork() // not connected
}
}
}
webLoaderThread.start()
安卓系统权限
不要忘记将以下权限添加到你的AndroidManifest.xml中
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
从以下链接找到并修改(!):
在你的manifest文件中至少添加:
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
如果您正在访问它，您可能已经拥有INTERNET权限。那么一个允许测试连通性的布尔函数是:
private boolean checkInternetConnection() {
ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
// test for connection
if (cm.getActiveNetworkInfo() != null
&& cm.getActiveNetworkInfo().isAvailable()
&& cm.getActiveNetworkInfo().isConnected()) {
return true;
} else {
Log.v(TAG, "Internet Connection Not Present");
return false;
}
}
下面是一些现代代码，使用AsynTask来解决android崩溃的问题，当你尝试在主线程上连接并为用户引入一个带有冲洗和重复选项的警报。
class TestInternet extends AsyncTask<Void, Void, Boolean> {
@Override
protected Boolean doInBackground(Void... params) {
try {
URL url = new URL("http://www.google.com");
HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
urlc.setConnectTimeout(3000);
urlc.connect();
if (urlc.getResponseCode() == 200) {
return true;
}
} catch (MalformedURLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
return false;
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return false;
}
return false;
}
@Override
protected void onPostExecute(Boolean result) {
if (!result) { // code if not connected
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setMessage("An internet connection is required.");
builder.setCancelable(false);
builder.setPositiveButton(
"TRY AGAIN",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
new TestInternet().execute();
}
});
AlertDialog alert11 = builder.create();
alert11.show();
} else { // code if connected
doMyStuff();
}
}
}
...
new TestInternet().execute();
