// TODO: Consider implementing this method using Android's ConnectivityManager
public synchronized boolean isNetworkUnavailable(long checkInterval) {
if (this.offlineMode) return true;
// If there's been success since failure, network assumed to be reachable.
if (this.lastAvailableLogTime.get() > this.lastUnavailableLogTime.get()) {
this.lastNetworkUnavailableResult.set(false);
return this.lastNetworkUnavailableResult.get();
}
long now = System.currentTimeMillis();
// If there's been success recently, network assumed to be reachable.
if (!this.lastNetworkUnavailableResult.get()
&& now - this.lastAvailableLogTime.get() < checkInterval) {
return this.lastNetworkUnavailableResult.get();
}
// If query comes too soon after an earlier one that addressed the network, return the earlier
// result.
if (now - this.lastNetworkCheckTime.get() < checkInterval) {
return this.lastNetworkUnavailableResult.get();
}
this.lastNetworkCheckTime.set(now);
if (!this.isWorldWindServerUnavailable()) {
this.lastNetworkUnavailableResult.set(false); // network not unreachable
return this.lastNetworkUnavailableResult.get();
}
for (String testHost : networkTestSites) {
if (isHostReachable(testHost)) {
{
this.lastNetworkUnavailableResult.set(false); // network not unreachable
return this.lastNetworkUnavailableResult.get();
}
}
}
if (now - this.lastNetworkStatusReportTime.get() > NETWORK_STATUS_REPORT_INTERVAL) {
this.lastNetworkStatusReportTime.set(now);
String message = Logging.getMessage("NetworkStatus.NetworkUnreachable");
Logging.info(message);
}
this.lastNetworkUnavailableResult.set(
true); // if no successful contact then network is unreachable
return this.lastNetworkUnavailableResult.get();
}
/**
* Determine if a host is reachable by attempting to resolve the host name, and then attempting to
* open a connection.
*
* @param hostName Name of the host to connect to.
* @return {@code true} if a the host is reachable, {@code false} if the host name cannot be
* resolved, or if opening a connection to the host fails.
*/
protected static boolean isHostReachable(String hostName) {
try {
// Assume host is unreachable if we can't get its dns entry without getting an exception
//noinspection ResultOfMethodCallIgnored
InetAddress.getByName(hostName);
} catch (UnknownHostException e) {
String message = Logging.getMessage("NetworkStatus.UnreachableTestHost", hostName);
Logging.verbose(message);
return false;
} catch (Exception e) {
String message = Logging.getMessage("NetworkStatus.ExceptionTestingHost", hostName);
Logging.verbose(message);
return false;
}
// Was able to get internet address, but host still might not be reachable because the address
// might have been
// cached earlier when it was available. So need to try something else.
URLConnection connection = null;
try {
URL url = new URL("http://" + hostName);
Proxy proxy = WWIO.configureProxy();
if (proxy != null) connection = url.openConnection(proxy);
else connection = url.openConnection();
connection.setConnectTimeout(2000);
connection.setReadTimeout(2000);
String ct = connection.getContentType();
if (ct != null) return true;
} catch (IOException e) {
String message = Logging.getMessage("NetworkStatus.ExceptionTestingHost", hostName);
Logging.info(message);
} finally {
if (connection instanceof HttpURLConnection) ((HttpURLConnection) connection).disconnect();
}
return false;
}