Chcę wiedzieć, co zostało zrobione, gdy URL.openconnection ().
zrobiłem taki test:

public static void main(String[] args) {
    //    testConnection("http://www.google.com");
    testConnection("http://219.09.34.23.1");
}

private static void testConnection(final String _url) {
    new Thread(new Runnable() {
        String strurl = _url;
        long starttime = 0;
        long endtime = 0;

        public void run() {
            try {
                System.out.println("open:" + strurl);

                starttime = System.currentTimeMillis();
                System.out.println("starttime:" + starttime);

                URL url = new URL(strurl);
                HttpURLConnection conn = (HttpURLConnection) url
                        .openConnection();

                endtime = System.currentTimeMillis();
                System.out.println("openConnection endtime:" + endtime);
                System.out
                        .println("spend:" + (endtime - starttime) + " ms");

                conn.connect();
                endtime = System.currentTimeMillis();
                System.out.println("connect endtime2:" + endtime);
                System.out
                        .println("spend:" + (endtime - starttime) + " ms");

                conn.getResponseCode();
                endtime = System.currentTimeMillis();
                System.out.println("endtime3:" + endtime);
                System.out
                        .println("spend:" + (endtime - starttime) + " ms");
            } catch (MalformedURLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();

                endtime = System.currentTimeMillis();
                System.out.println("MalformedURLException endtime:"
                        + endtime);
                System.out
                        .println("spend:" + (endtime - starttime) + " ms");
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();

                endtime = System.currentTimeMillis();
                System.out.println(" IOException endtime:" + endtime);
                System.out
                        .println("spend:" + (endtime - starttime) + " ms");
            }

        }
    }).start();
}

kiedy uruchamiam testConnection („http://www.google.com”), wszystko jest w porządku.
kiedy uruchomię testConnection („http: //219.09.34.23.1”), „219.09.34.23.1” jest przypadkowym ip, który może nie istnieje, napisałem to, drukuje to:

open:http://219.09.34.23.1
starttime:1338978920350
openconnection endtime:1338978920355
spend:5 ms

    java.net.UnknownHostException: 219.09.34.23.1  
    at java.net.PlainSocketImpl.connect(Unknown Source)  
    at java.net.SocksSocketImpl.connect(Unknown Source)  
    at java.net.Socket.connect(Unknown Source)  
    at java.net.Socket.connect(Unknown Source)  
    at sun.net.NetworkClient.doConnect(Unknown Source)  
    at sun.net.www.http.HttpClient.openServer(Unknown Source)  
    at sun.net.www.http.HttpClient.openServer(Unknown Source)  
    at sun.net.www.http.HttpClient.<init>(Unknown Source)  
    at sun.net.www.http.HttpClient.New(Unknown Source)  
    at sun.net.www.http.HttpClient.New(Unknown Source)  
    at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(Unknown Source)  
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)  
    at sun.net.www.protocol.http.HttpURLConnection.connect(Unknown Source)  
    at Main$1.run(Main.java:37)  
    at java.lang.Thread.run(Unknown Source)

IOException endtime:1338978920393
spend:43 ms

oznacza to, że spędził 5 ms na uruchomieniu openconnection i spędził 43ms na znalezieniu nieznanego hosta, moim problemem jest to, co zostało zrobione, gdy URL.openconnection () jako „219.09.34.23.1” jest nieznanym hostem? Dzięki za pomoc!