使用udp创建一个简单聊天工具

package com.diedline.socket;

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import java.text.SimpleDateFormat;
import java.util.Date;

import static javax.swing.SwingConstants.SOUTH;

public class Demo4_GUIChat extends Frame {

    private TextField tf;
    private Button send;
    private Button log;
    private Button clear;
    private Button shake;
    private TextArea viewText;
    private TextArea sendText;
    private DatagramSocket socket;
    private BufferedWriter bw;
    private String str;

    /**
     * GUI聊天
     *
     * @param
     */
    public Demo4_GUIChat() throws InterruptedException, IOException {
        init();
//        Thread.sleep(10);
        centerPanel();
//        Thread.sleep(10);
        southPanel();
        event();

    }

    public void event() {
        this.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                socket.close();                             //在退出虚拟机之前把socket关闭
                try {
                    bw.close();                             // 将文件关闭
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
                System.exit(0);
            }
        });
        send.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                try {
                    send();
                } catch (SocketException e1) {
                    e1.printStackTrace();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            }
        });
        log.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                try {
                    logFile();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            }
        });

        clear.addActionListener(new ActionListener() {                  //清屏
            @Override
            public void actionPerformed(ActionEvent e) {
                viewText.setText("");
            }
        });
        //震动方法
        shake.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                try {
                    send(new byte[]{-1}, tf.getText());              //发送-1字节
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            }
        });
        //快捷键功能
        sendText.addKeyListener(new KeyAdapter() {
            @Override
            public void keyReleased(KeyEvent e) {
//                if(e.getKeyCode() == KeyEvent.VK_ENTER && e.isControlDown() ){        //回车和ctrl同时按下的情况
                if (e.getKeyCode() == KeyEvent.VK_ENTER) {                                 //回车按下的情况
                    try {
                        send();
                    } catch (IOException e1) {
                        e1.printStackTrace();
                    }
                }
            }
        });
    }

    //震动功能
    private void shake() throws InterruptedException {
        int x = this.getLocation().x;               //获取横坐标位置
        int y = this.getLocation().y;               //获取纵坐标位置
        for (int i = 0; i < 10; i++) {
            this.setLocation(x + 20, y + 20);
            Thread.sleep(20);
            this.setLocation(x + 20, y - 20);
            Thread.sleep(20);
            this.setLocation(x - 20, y + 20);
            Thread.sleep(20);
            this.setLocation(x - 20, y - 20);
            Thread.sleep(20);
            this.setLocation(x, y);
        }

    }


    //历史记录功能
    private void logFile() throws IOException {
        bw.flush();                             //刷新缓存区
        FileInputStream fis = new FileInputStream("config.txt");
        ByteArrayOutputStream baos = new ByteArrayOutputStream();           //在内存中创建缓冲区
        int len;
        byte[] arr = new byte[8192];
        while ((len = fis.read(arr)) != -1) {
            baos.write(arr, 0, len);
        }
        String str = baos.toString();               //将内存中的内容转换成字符串
        viewText.setText(str);                      //设置聊天记录
        fis.close();                                //关闭内存输出流
    }

    //重载的发送方法
    private void send(byte[] arr, String ip) throws IOException {
        DatagramPacket packet =                             //创建数据包 设定数据，大小，和端口号
                new DatagramPacket(arr, arr.length, InetAddress.getByName(ip), 9999);
        socket.send(packet);                    //将数据发送出去
    }


    //发送功能
    private void send() throws IOException {
        String message = sendText.getText();                //获取发送区域的内容
        String ip = tf.getText();                           //获取 ip
        //如果没有ip写着就将默认ip设置为255.255.255.255
        ip = ip.trim().length() == 0 ? "255.255.255.255" : ip;
        send(message.getBytes(), ip);             //调用 重载的send方法
        String time = getCurrentTime();         //获取当前时间

        str = time + "我对" + (ip.equals("255.255.255.255")?"所有人":ip) + "说：" + "\r\n" + message + "\r\n";
        bw.write(str);                      //将信息写到数据库中 （现在是文本文档模拟）
        viewText.append(str);               //将信息添加到显示区域中
        sendText.setText(null);                 //清除输入
    }

    private String getCurrentTime() {
        Date d = new Date();                //创建当前日期对象
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
        return sdf.format(d);                  //将时间格式化
    }


    public void centerPanel() {
        Panel center = new Panel();             //创建中间的panel
        //显示的文本区域
        viewText = new TextArea();
        viewText.setEditable(false);            //设置成不可编辑
        viewText.setBackground(Color.white);               //设置背景颜色
        //发送的文本区域
        sendText = new TextArea(5, 1);
        center.setLayout(new BorderLayout());         //设置边界布局管理器
        center.add(sendText, BorderLayout.SOUTH);        //发送文本区域放在南边
        center.add(viewText, BorderLayout.CENTER);       //显示区域放在中间
        this.add(center, BorderLayout.CENTER);
        sendText.setFont(new Font("xxx", Font.PLAIN, 15));
        viewText.setFont(new Font("xxx", Font.PLAIN, 15));
        this.setVisible(true);
    }

    public void southPanel() {
        Panel south = new Panel();              //创建南边的panel
        //创建文本字段 存储ip地址
        tf = new TextField(15);
        tf.setText("127.0.0.1");
        //创建发送按钮
        send = new Button("发送");
        //创建记录
        log = new Button("记录");
        //清屏
        clear = new Button("清屏");
        //创建震动按钮
        shake = new Button("震动");
        south.add(tf);
        south.add(send);
        south.add(log);
        south.add(clear);
        south.add(shake);
        this.add(south, BorderLayout.SOUTH);                 //将Panel放在Frame的南边
        this.setVisible(true);
    }

    public void init() throws IOException {
        this.setLocation(500, 50);
        this.setSize(400, 600);
        socket = new DatagramSocket();                   //创建socket 使用随机端口号
        bw = new BufferedWriter(new FileWriter("config.txt", true));         //需要在尾部追加
        new Receive().start();                          //开启接收线程
        this.setVisible(true);
    }

    //接收和发送需要同时执行 所以定义成多线程的
    private class Receive extends Thread {
        private String str;

        @Override
        public void run() {
            try {
                DatagramSocket socket = new DatagramSocket(9999);
                DatagramPacket packet = new DatagramPacket(new byte[8192], 8192);
                while (true) {
                    socket.receive(packet);                         //接收信息
                    byte[] arr = packet.getData();                  //获取字节数据
                    int len = packet.getLength();                   //获取有效的字节数据
                    if (arr[0] == -1 && len == 1) {                   //如果发过来的数组的第一个存贮的值是-1并且数组长度是-1
                        shake();                                    //调用震动方法
                        continue;                                   //中止本次循环  进行下次循环 因为震动不需要使用下面的方法
                    }
                    String message = new String(arr, 0, len); //转换成字符串
                    String time = getCurrentTime();                 //获取当前时间
                    String ip = packet.getAddress().getHostAddress();       //获取ip地址
                    str = time + " " + ip + " 对我说：\r\n" + message + "\r\n";
                    viewText.append(str);
                    bw.write(str);              //将信息写入数据库
                }
            } catch (SocketException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

        }
    }


    //主方法 调用构造方法
    public static void main(String[] args) throws InterruptedException, IOException {
        new Demo4_GUIChat();

    }
}