Java之局域网通信聊天

  前段时间学到Socket套接字，对tcp/ip通信很感兴趣，便想编写测试下，很是简单。写到博客上分享下，最重要的是有一些不明白的问题希望有人给予解答。本实例采用DatagramSocket、DatagramPacket通信，指定目标IP地址即可发送信息，可向局域网外的公网IP主机发信息，如何接受来自公网IP的信息？如何穿透路由器到达指定内网IP主机？

  设计思路：需要GUI组件简单设计个页面；局域网通信，用tcp通信，client对client，所以只编写一个client就好了；client之间通信用DatagramSocket、DatagramPacket收发数据包，同时用多线程分别封装发送数据包，接收数据包；最后解析数据包，用IO流解析得到的信息，显示在文本区。

  页面：

  过于简单直接发代码：

import java.awt.BorderLayout;

import java.awt.Dimension;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

import java.net.SocketException;

import java.net.UnknownHostException;

import java.text.DateFormat;

import java.text.SimpleDateFormat;

import java.util.Date;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JPanel;

import javax.swing.JScrollPane;

import javax.swing.JTextArea;

import javax.swing.JTextField;

import javax.swing.*;

public class chat

{

private JLabel ipjl;

private JLabel portjl;

private JTextField ipjtf;

private JTextField portjtf;

private JScrollPane messagejs;

private JScrollPane sendjs;

private JTextArea messagejta;

private JTextArea sendjta;

private JButton sendjb;

private DatagramSocket dgssend;

private DatagramSocket dgsrece;

private DatagramPacket dgp;

private String message;

private String readmessage;

private InetAddress ip;

private int port;

public chat() throws IOException

{

dgssend = new DatagramSocket();

dgsrece = new DatagramSocket(8888);

dgp = null;

message = null;

creatFrame();

readmessages sm = new readmessages();

Thread t = new Thread(sm);

t.start();

}

public void creatFrame()

{

JFrame chatroom = new JFrame("聊天");

chatroom.setLayout(new BorderLayout());

chatroom.setBounds(650, 200, 800, 680);

JPanel north = new JPanel();

JPanel center = new JPanel();

JPanel south = new JPanel();

north.setPreferredSize(new Dimension(820,80));

south.setPreferredSize(new Dimension(820,160));

chatroom.add(north,BorderLayout.NORTH);

chatroom.add(center);

chatroom.add(south,BorderLayout.SOUTH);

ipjl = new JLabel("对方IP地址");

ipjtf = new JTextField("",15);

portjl = new JLabel("对方端口");

portjtf = new JTextField("8888",15);

messagejta = new JTextArea("",20,70);

messagejs = new JScrollPane(messagejta);

messagejta.setEditable(false);

sendjta = new JTextArea("",6,70);

sendjs = new JScrollPane(sendjta);

sendjb = new JButton("发送");

sendjb.addActionListener(new sendmessage());

north.add(ipjl);

north.add(ipjtf);

north.add(portjl);

north.add(portjtf);

center.add(messagejs);

south.add(sendjs);

south.add(sendjb);

chatroom.setVisible(true);

chatroom.setDefaultCloseOperation(chatroom.EXIT_ON_CLOSE);

}

class sendmessage implements ActionListener {

@Override

public void actionPerformed(ActionEvent arg0) {

try{

message = sendjta.getText();

ip = InetAddress.getByName(ipjtf.getText());

port = Integer.parseInt(portjtf.getText());

dgp = new DatagramPacket(message.getBytes(),message.getBytes().length,ip,port);

Date date = new Date();

DateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

messagejta.append("我: " +format.format(date) + '\n');

messagejta.append( message +" "+ '\n');

// messagejta.setText(messagejta.getText()+"\r\n"+"我："+message+"\r\n");

dgssend.send(dgp);

sendjta.setText("");

}catch(Exception e)

{e.printStackTrace();}

}

}

class readmessages implements Runnable

{

@Override

public void run() {

while(true)

{

try{

byte[] buf = new byte[1024];

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

dgsrece.receive(dgpread);

String readmessage = new String(dgpread.getData(),0,dgpread.getLength());

// ipjtf.setText(dgpread.getAddress().toString());

// portjtf.setText(dgpread.getPort()+"");

Date date = new Date();

DateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

messagejta.append(dgpread.getAddress().toString()+": " +format.format(date) + '\n');

messagejta.append( readmessage + '\n');

// messagejta.setText(messagejta.getText()+"\r\n"+dgpread.getAddress().toString()+":"+readmessage);

}

catch(Exception e)

{e.getStackTrace();}

}

}

}

public static void main(String[] args) throws IOException

{

// TODO Auto-generated method stub

new chat();

}

}