一個簡單UDP通信程序的問題

 最近在學java網絡編程，我寫了一個小的udp程序，不過遇到一個問題：

 

如圖，192.168.3.2是內網主機，通過192.168.3.1代理上網

            192.168.3.1是服務器，裏面添加了路由和遠程訪問角色，一做nat端口映射

            10.59.12.99是外網主機

            所有主機都沒有開啓防火牆

當前，192.168.3.2和10.59.12.99都有該聊天程序，兩臺主機可以通信，通過192.168.3.2可以向10.59.12.99發送消息

問：如何從10.59.12.99向192.168.3.2發送消息？？？

程序截圖：

 

端口映射截圖：

 

程序如下：

 

package lwb.it.gui.chat;

import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.List;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class ChatRoom {

    static JTextField fieldIP = null;
    static JTextField fieldDT =null;
    static List list = null;
    static DatagramPacket datagramPacket = null;
    static DatagramSocket datagramSocket = null;
    /**
     * @param args
     */
    public static void main(String[] args)  {

        try {
            datagramSocket = new DatagramSocket(3500);
        } catch (SocketException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        final JFrame frame = new JFrame("聊天室");
        frame.setLayout(new FlowLayout());
        list = new List(10);
        JPanel p = new JPanel();
        frame.add(list);
        frame.add(p);
        fieldIP =  new JTextField(10);
        fieldDT = new JTextField(16);
        final JButton button = new JButton("發送");
        p.add(fieldIP);
        p.add(fieldDT);
        frame.add(button);
        list.setSize(new Dimension(300, 400));
        p.setPreferredSize(new Dimension(310, 20));

        p.setLocation(0, 200);

        frame.setBounds(200,200,320,260);
        frame.setResizable(false);
        frame.setVisible(true);
        new Thread(new Runnable() {

            @Override
            public void run() {


                button.addActionListener(new ActionListener() {

                    @Override
                    public void actionPerformed(ActionEvent e) {
                        String IP = fieldIP.getText();
                        String DT = fieldDT.getText();

                        try {


                                byte [] buf = DT.getBytes("utf-8");
                                datagramPacket = new DatagramPacket(buf,
                                        buf.length,
                                        InetAddress.getByName(IP), 2000);
                                datagramSocket.send(datagramPacket);
                                // datagramSocket.close();
                                fieldDT.setText(null);
                        } catch (Exception exception) {
                            exception.printStackTrace();
                        }
                    }
                });
            }
        }).start();
        new Thread(new Runnable() {

            @Override
            public void run() {
                try {
                    DatagramSocket datagramSocket = new DatagramSocket(2000);
                    byte[] buf = new byte[512];
                    DatagramPacket datagramPacket = new DatagramPacket(buf, 512);
                    while (true) {
                        datagramSocket.receive(datagramPacket);
                        list.add(new String(datagramPacket.getData(), 0,
                                datagramPacket.getLength(),"utf-8") +"   -- " +datagramPacket.getAddress().getHostAddress() + " :"+ datagramPacket.getPort());
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
                frame.addWindowListener(new WindowListener() {
                    @Override
                    public void windowClosing(WindowEvent e) {
                        datagramSocket.close();
                        System.out.println("123");
                        e.getWindow().dispose();
                    }

                    @Override
                    public void windowClosed(WindowEvent e) {
                        System.exit(0);
                    }

                    @Override
                    public void windowOpened(WindowEvent e) {
                        // TODO Auto-generated method stub

                    }

                    @Override
                    public void windowIconified(WindowEvent e) {
                        // TODO Auto-generated method stub

                    }

                    @Override
                    public void windowDeiconified(WindowEvent e) {
                        // TODO Auto-generated method stub

                    }

                    @Override
                    public void windowActivated(WindowEvent e) {
                        // TODO Auto-generated method stub

                    }

                    @Override
                    public void windowDeactivated(WindowEvent e) {
                        // TODO Auto-generated method stub

                    }

                });
            }
        }).start();

    }
}