JAVA实现UDP组播聊天程序

编程语言：Java1.5（运行在JVM(Java Virsual Machine)）

开发工具：eclipce3.2

测试环境：局域网

二、实验目的

社会已经进入信息时代,网络技术在飞速发展.大量应用都依赖于从一个主机向多个主机或者从多个主机向多个主机发送同一信息的能力,在Internet上分布的数目可能达数十万台,这些都需要更高的带宽,并且大大超出了单播的能力.一种能最大限度地利用现有带宽的重要技术是IP组播.

三、组播聊天程序的实现：

/**

 * 该程序实现了简单组播聊天功能；

 * 步骤：

 * 1、利用java.net包中的MulticastSocket生成对象s;

 * 2、设置组播地址group=InetAddress.getByName("228.9.6.8");

 * 3、加入组播s.joinGroup(group);

 * 4、将要发送的所有信息封装成一个数据报data=DatagramPacket的一个实例;

 * 5、数据报的头部放入聊天人的别名name;

 * 6、发送处理好的数据包：s.send(data);

 * 7、创建一个接受数据报的队列recv：DatagramPacket(buf, buf.length)，队列大小为100字节;

 * 8、创建一个监听线程，线程中执行数据包的接受功能：s.receive(recv);

 * 9、聊天记录可以手动保存至”Note.txt”文件中;

* 作者：蓝蔡

*/

import java.net.*;

import java.awt.event.*;

import java.awt.*;

import java.io.*;

import javax.swing.*;

public class MutilCast {

    public static void main(String[] args)

    {

        MulticastSocket s              = null;

        InetAddress group               = null;    

        JPanel northPanel               =new JPanel();   

        JPanel southPanel               =new JPanel();

        JPanel namePanel                =new JPanel(new FlowLayout());

        JLabel sendLabel                =new JLabel("发送内容：");

        JLabel nameChangeLabel          =new JLabel("给自己起个名字：");

final    JTextField nameSpace           =new JTextField(20);

final    JTextArea messageArea          =new JTextArea("",20,20);

final    JTextField sendField            =new JTextField(30);

        JScrollPane message              =new JScrollPane(messageArea);

        JButton sendButton               =new JButton("发送");

        JButton saveButton               =new JButton("保存记录");

        JButton clearUpButton            =new JButton("清空面板");

        Box    centerBox                  =Box.createVerticalBox();

        namePanel.add(nameChangeLabel);

        namePanel.add(nameSpace);

        centerBox.add(namePanel);

        centerBox.add(message);   

      //实现组播数据传送的配置信息

        try {

             group = InetAddress.getByName("228.9.6.8");

        } catch (UnknownHostException e1) {

            System.out.println("组播地址绑定失败");

        }      

        try {

            s = new MulticastSocket(6789);

        } catch (IOException e1) {

            System.out.println("组播地址创建失败");

        }

        try {

                s.joinGroup(group);

        } catch (IOException e1) {

            System.out.println("组播地址加入失败");

        }

      //end实现组播数据传送的配置信息

      //“发送”按钮实现信息功能的发送部分                  

        class SendMsg implements ActionListener

        {

            String msg=null;         

            MulticastSocket s=null;

            InetAddress group = null;

            public SendMsg(MulticastSocket s,InetAddress group)

            {

                this.s=s;

                this.group=group;

            }

            public void actionPerformed(ActionEvent e)

            {              

                 try

                {

                     //如果名字为空 给出提示信息

                    if(nameSpace.getText().isEmpty())                   

                        new JOptionPane().showMessageDialog(null, "请一定要取别名！");

                    else

                    {

                    //如果名字不为空 则把名字添加到数据报头

                    msg=(nameSpace.getText()+"说："+sendField.getText());

DatagramPacket data=

 new DatagramPacket(msg.getBytes(),msg.getBytes().length,group, 6789);

                    s.send(data);

                    }

                 }

                 catch (IOException e1) {

                    System.out.println("发送失败");

                }      

            }

        }

         //实现数据报的接受线程      

        class  recevMsg extends Thread

        {

             MulticastSocket s=null;

             public recevMsg(MulticastSocket s)

             {

                 this.s=s;

             };

             public void run()

             {

                 byte[] buf = new byte[100];

                DatagramPacket recv = new DatagramPacket(buf, buf.length);

                 try

                 {

                     while(true)

                     {

                         s.receive(recv);

                         String str=new String(recv.getData());

                          String line =System.getProperty("line.separator");

                         messageArea.append(str);

                         messageArea.append(line);

                     }

                 }

                 catch (IOException e1)

                 {

                     System.out.println("接受失败");

                 }

             }

        }

       //聊天记录的保存 保存在当前位置下的"Note.txt"文件中

        class SaveMsg implements ActionListener

        {

            String msg=null;

            String line =System.getProperty("line.separator");

            public void actionPerformed(ActionEvent e)

            {              

                 try

                 {

                    msg=messageArea.getText();

                     FileOutputStream Note=new FileOutputStream("Note.txt");

                    messageArea.append("记录已经保存在Note.txt");

                    Note.write(msg.getBytes());

                    messageArea.append(line);

                    Note.close();

                 }

                 catch (IOException e1) {

                    System.out.println("发送失败");

                }      

            }

        }

        //清除面板上的聊天记录

        class ClearMsg implements ActionListener

        {

            public void actionPerformed(ActionEvent e)

            {              

                 try

                 {

                     messageArea.setText("");

                 }

                 catch (Exception e1) {

                    System.out.println("清空失败");

                }      

            }

        }

        JFrame mutilCastFrame=new JFrame("组播聊天工具");

        northPanel.add(sendLabel);

        northPanel.add(sendField);

        northPanel.add(sendButton);

        southPanel.add(saveButton);

        southPanel.add(clearUpButton);

        mutilCastFrame.getContentPane().add(northPanel,"North");

        mutilCastFrame.getContentPane().add(southPanel,"South");  

        mutilCastFrame.getContentPane().add(centerBox,"Center");

mutilCastFrame.setDefaultCloseOperation(mutilCastFrame.EXIT_ON_CLOSE); 

sendButton.addActionListener(new SendMsg(s,group));

        saveButton.addActionListener(new SaveMsg());

        clearUpButton.addActionListener(new ClearMsg());

        mutilCastFrame.setSize(500, 500);

        mutilCastFrame.setLocation(200, 200);

        mutilCastFrame.show();

        recevMsg r=new recevMsg(s);

        r.start();

        }

}