Java中的线程DNS服务器

我正在尝试用java创建一个简单的DNS服务器。这是我的密码：

public class DNSServer{
        public static final int DEFAULT_PORT = 6052;
        private static ServerSocket sock = null;
        static Socket client;

        public static void main(String[] args) 
        {
            try
            {
                ServerSocket sock = new ServerSocket(DEFAULT_PORT);

                /* now listen for connections */
                while(true)
                {
                    System.out.println("Server is listening...\n");
                    client = sock.accept();
                    System.out.println("Client connected\n");

                    // create a separate thread
                    // to service the request
                    Thread worker = new Thread(new Connection(client));
                    worker.start(); 

                }
            }   
            catch (IOException ioe) {
                System.err.println(ioe);
            }
              finally {
                    //close Socket
                    try {
                        client.close();
                    } catch (IOException ioe) {
                        System.err.println(ioe);
                    }
            }

        }

}

}

}

但是，当我提供一个参数url并按enter键时，程序就会卡住。。 有什么问题吗？我做错了什么

我们将不胜感激。 多谢各位

---

编辑：

您是否尝试过使用调试器单步调试代码？不，我们的讲师说调试在这里没有用，因为我们通过命令提示符运行所有程序。您不必通过命令提示符运行所有程序。说真的，用调试器一步一步地完成这个过程——你会发现这个过程非常有用。如果你不愿意使用IDE和调试器，至少要添加更多的日志记录并将输出添加到你的帖子中。你应该证明你理解你所问的主题，而不仅仅是复制/粘贴别人的代码。

public class Connection implements Runnable {

private Socket client=null;
private BufferedReader fromClient = null;
private PrintWriter toClient = null;
private String hostAddress;

public Connection(Socket client) 
{
    this.client=client;
}

@Override
public void run()
{
    try
    {
    fromClient = new BufferedReader(new InputStreamReader(client.getInputStream()));
    toClient = new PrintWriter(client.getOutputStream(), true);

    String nameRequest = fromClient.readLine(); //Reading from Socket
    InetAddress hostInetAddress = InetAddress.getByName(nameRequest);
    hostAddress = hostInetAddress.getHostAddress();
    toClient.println(hostAddress); //Writing the Result IP address (as a String) to the Socket

    }
    catch(UnknownHostException uhe){
        hostAddress = "Unknown Host";
    }
    catch(IOException ioe){
        System.err.println(ioe);
    }
    finally
    {
        try {
            fromClient.close();
        } catch (IOException ioe) {
            System.err.println(ioe);
        }
        toClient.close();
        try {
            client.close();
        } catch (IOException ioe) {
            System.err.println(ioe);
        }
    }

}

public class DNSClient {
    public static final int DEFAULT_PORT = 6052;
    private static Socket sock;
    private static BufferedReader fromServer;
    private static PrintWriter toServer;

    public static void main(String[] args){

        if(args.length==0)
        {
            System.out.println("Usage: java DNSClient [host name]");
            System.exit(1);
        }
        else
        {
            try
            {
            sock = new Socket("127.0.0.1", DEFAULT_PORT );

            toServer = new PrintWriter(args[0]); //send hostname to server
            fromServer = new BufferedReader(new InputStreamReader(sock.getInputStream())); //read host IP from server

            //print output
            System.out.println(args[0] + " = " + fromServer.readLine());
            }

            catch(IOException ioe){
                System.err.println(ioe);
            }
            finally{
                toServer.close();
                try {
                    fromServer.close();
                } catch (IOException ioe) {
                    System.err.println(ioe);
                }
                try {
                    sock.close();
                } catch (IOException ioe) {
                    System.err.println(ioe);
                }
            }



        }
    }