java UDP可靠通信,该如何处理

import java.awt.*;import java.awt.event.*;import java.io.*;import java.net.*;import java.util.*;import javax.swing.*;import java.util.regex.*;;public class PointToPointUDPChat {    Frame f = new Frame("聊天室");    Label lbRemoteIP = new Label("目标IP");// 对方IP    Label lbRemotePort = new Label("目标端口");    Label lbLocalSendPort = new Label("本地发送端口");    Label lbLocalReceivePort = new Label("本地接收端口");    TextField tfRemoteIP = new TextField(15);// 要发送数据的目标IP    TextField tfRemotePort = new TextField(15);// 要发送数据的目标端口    TextField tfLocalSendPort = new TextField(15);// 使用此端口发送数据    TextField tfLocalReceivePort = new TextField(15);// 使用此端口发送数据    String remoteIP = null;    int remotePort = 0;    int localSendPort = 0;    int localReceivePort = 0;        TextArea allChatContent = new TextArea();    TextField sendChatContent = new TextField(20);    Button connect = new Button("连接");    Button disConnect = new Button("断开");    Button bt = new Button("发送");    Thread receiveThread = null;// 利用start和stop控制是否接收消息    public PointToPointUDPChat() {    initFrame();    }    public static void main(String args[]) {    new PointToPointUDPChat();    }    // 外观布局，添加事件响应    public void initFrame() {// //////    f.setSize(400, 500);// 设置容器的大小    f.setLayout(new BorderLayout());    Panel p = new Panel();    Panel p2 = new Panel();    // 添加组件，布置布局    p.setLayout(new GridLayout(5, 5));    p.add(lbRemoteIP);    p.add(tfRemoteIP);    p.add(lbRemotePort);    p.add(tfRemotePort);    p.add(lbLocalSendPort);    p.add(tfLocalSendPort);    p.add(lbLocalReceivePort);    p.add(tfLocalReceivePort);    p.add(connect);    p.add(disConnect);    f.add("North", p);    connect.addActionListener(new ActionListener() {// 连接按钮事件            public void actionPerformed(ActionEvent e) {            try {                remoteIP = tfRemoteIP.getText();                remotePort = Integer.parseInt(tfRemotePort                    .getText());                localSendPort = Integer.parseInt(tfLocalSendPort                    .getText());                localReceivePort = Integer                    .parseInt(tfLocalReceivePort.getText());            } catch (Exception exception) {                prompt("连接信息不能为空或格式错误");                return;            }            if (!checkIP(remoteIP)) {                prompt("目标IP设置错误");                return;            }            if (!checkPort(remotePort)) {                prompt("目标端口设置错误");                return;            }            if (!checkPort(localSendPort)) {                prompt("本地发送端口设置错误");                return;            }            if (!checkPort(localReceivePort)) {                prompt("本地接收端口设置错误");                return;            }            prompt("连接成功");            tfRemoteIP.setEditable(false);            tfRemotePort.setEditable(false);            tfLocalReceivePort.setEditable(false);            tfLocalSendPort.setEditable(false);            receiveMessage();            }        });    disConnect.addActionListener(new ActionListener() {// 断开按钮事件            public void actionPerformed(ActionEvent e) {            tfRemoteIP.setEditable(true);            tfRemotePort.setEditable(true);            tfLocalReceivePort.setEditable(true);            tfLocalSendPort.setEditable(true);            tfLocalReceivePort.setText("");            tfLocalSendPort.setText("");            tfRemoteIP.setText("");            tfRemotePort.setText("");            remoteIP = null;            remotePort = 0;            localSendPort = 0;            localReceivePort = 0;            receiveThread.stop();            prompt("断开成功");            }        });    f.add("Center", allChatContent);    p2.setLayout(new FlowLayout());    p2.add(bt);    p2.add(sendChatContent);// ///p2面板添加发送按钮和要发送的内容    f.add("South", p2);    f.setVisible(true);// 让容器可显示    f.setResizable(false);// 不可改变容器大小    // 关闭窗口事件    f.addWindowListener(new WindowAdapter() {        public void windowClosing(WindowEvent e) {        f.setVisible(false);        f.dispose();        System.exit(0);        }    });    // //////触发发送按钮事件    bt.addActionListener(new ActionListener() {        public void actionPerformed(ActionEvent e) {        sendMessage();        }    });    // 模态显示按钮的触发事件    // 输入文本框的触发事件    sendChatContent.addActionListener(new ActionListener() {        public void actionPerformed(ActionEvent e) {        sendMessage();        }    });    }    // 发送数据    public void sendMessage() {//     // 定义ds    DatagramSocket ds = null;    try {        ds = new DatagramSocket(localSendPort);    } catch (SocketException e1) {        prompt("本地发送端口已被使用");        return;    }    // 设置发送信息    String sendMessage = sendChatContent.getText().trim();    if (sendMessage.equals("")) {        prompt("无效信息");        return;    }    byte[] buf = sendMessage.getBytes();// /////获得要发送的数据    // 设置接收数据的远程IP地址    InetAddress inetAddress = null;    try {        inetAddress = InetAddress.getByName(tfRemoteIP.getText().trim());    } catch (UnknownHostException e) {        prompt("非法远程IP地址");        return;    }    // 发送    DatagramPacket dp = new DatagramPacket(buf, 0, buf.length, inetAddress,        remotePort);    try {        ds.send(dp);    } catch (IOException e) {        prompt("网络故障，发送失败");        return;    }    sendChatContent.setText("");// //发送完数据，发送框重置为空    allChatContent.append(new java.text.SimpleDateFormat(        "yy-MM-dd HH:mm:ss").format(new Date())        + " send to Remote("        + dp.getAddress()        + " "        + dp.getPort()        + ") :\n");    allChatContent.append(sendMessage + "\n");    ds.close();    }    // 接收数据    class MyRunnable implements Runnable {    byte buf[] = new byte[1024];    DatagramSocket ds = null;    DatagramPacket dp = null;    public void run() {        dp = new DatagramPacket(buf, 0, 1024);        try {        ds = new DatagramSocket(localReceivePort);        } catch (SocketException e1) {        prompt("本地接收端口已被使用");        return;        }        while (true) {        try {            ds.receive(dp);        } catch (IOException e) {            ds.close();            e.printStackTrace();        }        String receiveMessage = new String(dp.getData(), 0, dp            .getLength());        allChatContent.append(new java.text.SimpleDateFormat(            "yy-MM-dd HH:mm:ss").format(new Date())//             + " from remote("            + dp.getAddress().getHostAddress()            + " " + dp.getPort() + ") :\n" + receiveMessage + "\n");        sendChatContent.setCaretPosition(sendChatContent.getText()            .length());        }    }    }    public void receiveMessage() {//        receiveThread = new Thread(new MyRunnable());    receiveThread.start();    }    // 异常处理    public void prompt(String promptMessage) {    JOptionPane.showConfirmDialog(null, promptMessage, "友情提示",        JOptionPane.WARNING_MESSAGE);    }    public boolean checkPort(int port) {    return String.valueOf(port).matches("\\d+") && port > 1024        && port <= 65535;    }    public boolean checkPort(String port) {    return port.matches("\\d+") && Integer.parseInt(port) > 1024        && Integer.parseInt(port) <= 65535;    }        public static boolean isDigit(String text) {    return text.matches("\\d+");    }          public boolean checkIP(String ip) {        java.util.regex.Matcher m = Pattern.compile(        "(\\d{1,3}).(\\d{1,3}).(\\d{1,3}).(\\d{1,3})").matcher(ip);    if (m.find()) {        for (int i = 1; i <= 4; i++)        if (Integer.parseInt(m.group(i)) < 0            || Integer.parseInt(m.group(i)) > 255)            return false;        return true;    }    return true;    }}