问题
I have basically the same problem explained here: Keep getting java.net.UnknownHostException after connecting to the internet
The problem is following, when my java application starts without Internet connection, it will forever continue throwing UnknownHostException, even in the casse when Internet connection is established.
The stack trace is quite huge:
javax.xml.ws.WebServiceException: Failed to access the WSDL at: http://www.taxifcd.de/DebugWirelessDataWebService/wdws?wsdl. It failed with:
www.taxifcd.de.
at com.sun.xml.internal.ws.wsdl.parser.RuntimeWSDLParser.tryWithMex(RuntimeWSDLParser.java:250)
at com.sun.xml.internal.ws.wsdl.parser.RuntimeWSDLParser.parse(RuntimeWSDLParser.java:231)
at com.sun.xml.internal.ws.wsdl.parser.RuntimeWSDLParser.parse(RuntimeWSDLParser.java:194)
at com.sun.xml.internal.ws.wsdl.parser.RuntimeWSDLParser.parse(RuntimeWSDLParser.java:163)
at com.sun.xml.internal.ws.client.WSServiceDelegate.parseWSDL(WSServiceDelegate.java:348)
at com.sun.xml.internal.ws.client.WSServiceDelegate.<init>(WSServiceDelegate.java:306)
at com.sun.xml.internal.ws.client.WSServiceDelegate.<init>(WSServiceDelegate.java:215)
at com.sun.xml.internal.ws.client.WSServiceDelegate.<init>(WSServiceDelegate.java:196)
at com.sun.xml.internal.ws.client.WSServiceDelegate.<init>(WSServiceDelegate.java:192)
at com.sun.xml.internal.ws.spi.ProviderImpl.createServiceDelegate(ProviderImpl.java:104)
at javax.xml.ws.Service.<init>(Service.java:77)
at de.dlr.ts.wirelessdata.ws.client.WirelessDataWebServiceImplService.<init>(WirelessDataWebServiceImplService.java:42)
at de.dlr.ts.wirelessdata.ws.client.WirelessDataWebServiceClient.<init>(WirelessDataWebServiceClient.java:62)
at de.dlr.dynamic.client.core.impl.bam.BAMImpl$PacketSender.init(BAMImpl.java:500)
at de.dlr.dynamic.client.core.impl.bam.BAMImpl$PacketSender.run(BAMImpl.java:534)
Caused by: java.net.UnknownHostException: www.taxifcd.de
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at java.net.Socket.connect(Socket.java:538)
at sun.net.NetworkClient.doConnect(NetworkClient.java:180)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:432)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:527)
at sun.net.www.http.HttpClient.<init>(HttpClient.java:211)
at sun.net.www.http.HttpClient.New(HttpClient.java:308)
at sun.net.www.http.HttpClient.New(HttpClient.java:326)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1169)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1105)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:999)
at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:933)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1513)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1441)
at java.net.URL.openStream(URL.java:1045)
at com.sun.xml.internal.ws.wsdl.parser.RuntimeWSDLParser.createReader(RuntimeWSDLParser.java:984)
at com.sun.xml.internal.ws.wsdl.parser.RuntimeWSDLParser.resolveWSDL(RuntimeWSDLParser.java:385)
at com.sun.xml.internal.ws.wsdl.parser.RuntimeWSDLParser.parse(RuntimeWSDLParser.java:216)
... 13 more
If I run program with Internet connection and after some time disconnect and connect it works good. I tried also with changing caching parameters of the network like this:
java.security.Security.setProperty("networkaddress.cache.ttl" , "0");
java.security.Security.setProperty("networkaddress.cache.negative.ttl" , "0");
But that also didn't help. Any idea how to solve this? It is obvious to me that the problem is in Java not recognizing the change on the network.
来源：https://stackoverflow.com/questions/38380537/jvm-appears-to-cache-failed-dns-lookups-even-if-caching-is-disabled