为什么connection.getResponseCode会抛IOException

下面是我的代码，testURL是另外一台机器，我在我的机器上call那个webservice的时候，会抛IOException，请高手指教问题出在哪里？

String testURL = "http://10.70.3.181:8080/test/wservices/mytest?wsdl";
URL url = new URL (testURL);
HttpURLConnection connection = (HttpURLConnection)url.openConnection ();
int state = connection.getResponseCode ();

IOException - if an error occurred connecting to the server.