java.net.UnknownHostException無法創建套接字。 Java的

Question

我閱讀了一些手冊，並嘗試創建Socket，如示例所示。

Socket socket = new Socket(InetAddress.getByName("http://google.com"), 80);

要么

Socket socket = new Socket("http://google.com", 80);

無論如何，我都會得到UnknownHostException：

java.net.UnknownHostException: http://google.com: Name or service not known

如何運作？

Answer 1

import java.io.*;
import java.net.*;

public class socket_client
{
    public static void main(String[] args) throws IOException 
    {
        Socket s = new Socket();
    String host = "www.google.com";

        try
        {
        s.connect(new InetSocketAddress(host , 80));
        }

        //Host not found
        catch (UnknownHostException e) 
        {
            System.err.println("Don't know about host : " + host);
            System.exit(1);
        }

        System.out.println("Connected");
    }
}

Answer 2

請嘗試www.google.com 。 我剛剛嘗試了telnet http://google.com ，但無法連接。 telnet www.google.com 80確實可以連接。