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();
}
}
我已经经历了所有的答案，我想出了我自己的答案，首先检查互联网是否可用，如果互联网可用，然后检查它是否活跃。
我已经包括了所有必要的方法和类来检查活跃的Internet连接。
NetworkUtils.class
public class NetworkUtils {
public static final int STATUS_CONNECTED = 0 ;
public static boolean isInternetAvailable(Context ctx){
ConnectivityManager cm = (ConnectivityManager)ctx.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
return activeNetwork != null && activeNetwork.isConnectedOrConnecting();
}
public static int isInternetActiveWithPing() {
try {
Runtime runtime = Runtime.getRuntime();
Process process = runtime.exec("/system/bin/ping -c 1 8.8.8.8");
int exitValue = process.waitFor();
return exitValue;
} catch (Exception ex) {
return -1;
}
}
public static boolean isInternetActiveWithInetAddress() {
try {
InetAddress inetAddress = InetAddress.getByName("www.google.com");
return inetAddress != null && !inetAddress.toString().equals("");
} catch (Exception ex) {
return false;
}
}
public static void displayInternetConnectionMessage(Context ctx){
Toast.makeText(ctx, "Check Internet Connection", Toast.LENGTH_SHORT).show();
}
}
你可以使用下面的代码检查互联网是否活跃:
private void checkInternetConnection() {
if (NetworkUtils.isInternetAvailable(this)) {
new Thread(new Runnable() {
@Override
public void run() {
if (NetworkUtils.isInternetActiveWithPing() == NetworkUtils.STATUS_CONNECTED) {
performNetworkingOperations();
} else {
if (NetworkUtils.isInternetActiveWithInetAddress()) {
performNetworkingOperations();
} else {
displayConnectionMessage();
}
}
}
}).start();
} else {
displayConnectionMessage();
}
}
private void performNetworkingOperations() {
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(MainActivity.this, "Internet is Available", Toast.LENGTH_SHORT).show();
}
});
}
private void displayConnectionMessage() {
runOnUiThread(new Runnable() {
@Override
public void run() {
NetworkUtils.displayInternetConnectionMessage(MainActivity.this);
}
});
}
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)
Kotlin和协程
我将函数放置在一个ViewModel中，该ViewModel具有viewModelScope。使用一个可观察的LiveData，我通知一个活动有关连接。
ViewModel
fun checkInternetConnection(timeoutMs: Int) {
viewModelScope.launch(Dispatchers.IO) {
try {
val socket = Socket()
val socketAddress = InetSocketAddress("8.8.8.8", 53)
socket.connect(socketAddress, timeoutMs)
socket.close()
_connection.postValue(true)
}
catch(ex: IOException) {
_connection.postValue(false)
}
}
}
private val _connection = MutableLiveData<Boolean>()
val connection: LiveData<Boolean> = _connection
活动
private fun checkInternetConnection() {
viewModel.connection.observe(this) { hasInternet ->
if(!hasInternet) {
//hasn't connection
}
else {
//has connection
}
}
}
if(isConnected()){
Toast.makeText(getApplication(),"Thank you",Toast.LENGTH_SHORT).show();
}
else{
AlertDialog.Builder builder =
new AlertDialog.Builder(this, R.style.AppCompatAlertDialogStyle);
builder.setTitle("Amar Bhat");
builder.setMessage("Oops...You are not connected to Internet!!!");
builder.setPositiveButton("OK", null);
builder.setNegativeButton("Cancel", null);
builder.show();
//Toast.makeText(getApplication(),"You are not connected",Toast.LENGTH_SHORT).show();
}
//And outside the class define isConnected()
public boolean isConnected(){
ConnectivityManager connMgr = (ConnectivityManager) getSystemService(Activity.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
if (networkInfo != null && networkInfo.isConnected())
return true;
else
return false;
}
// In minifest add these permission
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
