Java学习笔记(二)-------客户端一对多（TCP）多人聊天小程序

实现原理：客户端之间实现信息共享，需要中间服务器端进行信息转发。设置一个ArrayList，存储客户端列表，服务器每收到消息，就去遍历数组中的Socket并将消息转发。服务器端每连接一个客户端，就产生一个新的线程。具体代码如下：

【服务器端】

package org.ning.study.swing;

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.FlowLayout;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.border.Border;

public class Server2 extends JFrame  {//实现聊天室多人聊天。 客户端一对多通信

	ServerSocket serverSocket = null;
	Socket clientSocket = null;
	ArrayList array = null;
	JTextArea ta;
	//构造器是没有返回值的
	public  Server2(){
		initSwing();
		initSocket();
	}
	public void initSwing(){
		Container container = this.getContentPane();
		ta = new JTextArea();
		
		container.setLayout(new BorderLayout());
		container.add(ta,BorderLayout.CENTER);
		JLabel label = new JLabel("输入聊天内容：");
		JTextField tf = new JTextField(40);
		JButton button = new JButton("发送");
		JPanel south = new JPanel();
		south.setLayout(new FlowLayout(FlowLayout.LEFT));
		south.add(label);
		south.add(tf);
		south.add(button);
		container.add(south,BorderLayout.SOUTH);
		this.setTitle("服务器端程序");
		this.setBounds(300, 200, 700, 350);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.validate();
		this.setVisible(true);
	}
	public void initSocket(){
		array = new ArrayList();
		try {
			serverSocket = new ServerSocket(4331);
			while(true){
				clientSocket = serverSocket.accept();
				//每增加一个客户端，就将其加入到array中
				array.add(clientSocket);
				ClientThread clientThread = new ClientThread(clientSocket);
				Thread t = new Thread(clientThread);
				t.start();
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	//主程序入口
	public static void main(String[] args) {
		Server2 server = new Server2();
	}
	
	//客户端线程--类中定义的类
	class ClientThread implements Runnable{
		
		private Socket clientSocket;
		private String str = null;
		DataInputStream in = null;
		DataOutputStream out = null;
		public  ClientThread(Socket clientSocket){
			this.clientSocket = clientSocket;
			try {
				in = new DataInputStream(clientSocket.getInputStream());
				out = new DataOutputStream(clientSocket.getOutputStream());
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		
		@Override
		public void run() {
			while(true){
				try {
					str = in.readUTF();
					ta.append(str + "\n");
					//服务端每次收到的信息，必须向所有的客户端发送
					DataOutputStream out = null;
					for(int i = 0; i < array.size(); i++){
						out = new DataOutputStream(array.get(i).getOutputStream());
						out.writeUTF(str);
					}
					
					Thread.sleep(1000);
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
			
		}
		
	}
}

【客户端】

package org.ning.study.swing;

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.net.UnknownHostException;

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

public class Client2 extends JFrame implements ActionListener, Runnable {
	Socket clientSocket = null;
	DataInputStream in = null;
	DataOutputStream out = null;
	String str = null;
	JButton button;
	JTextField tf;
	JTextArea ta;
	Thread thread;
	public Client2(){
		thread = new Thread(this);
		initSwing();
		initSocket();
	}
	
	public void initSwing(){
		Container container = this.getContentPane();
		JPanel panel = new JPanel();
		JLabel label = new JLabel("输入聊天内容：");
		tf = new JTextField(40);
		button = new JButton("发送");
		button.addActionListener(this);
		panel.setLayout(new FlowLayout(FlowLayout.LEFT));
		panel.add(label);
		panel.add(tf);
		panel.add(button);
		ta = new JTextArea();
		container.setLayout(new BorderLayout());
		container.add(ta,BorderLayout.CENTER);
		container.add(panel,BorderLayout.SOUTH);
		this.setTitle("客户端程序");
		this.setBounds(300, 200, 700, 350);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.validate();
		this.setVisible(true);
	}
	public void initSocket(){
		try {
			clientSocket = new Socket("127.0.0.1", 4331);
			in = new DataInputStream(clientSocket.getInputStream());
			out = new DataOutputStream(clientSocket.getOutputStream());
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		//启动线程
		thread.start();
	}
	
	
	
	@Override
	public void run() {
		while(true){//一直监听是否有信息发来
			try {
				str = in.readUTF();
				ta.append(str + "\n");
				
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

	@Override
	public void actionPerformed(ActionEvent e) {
		if(e.getSource() == button){
			try {
				out.writeUTF(tf.getText());
			} catch (IOException e1) {
				e1.printStackTrace();
			}
		}
	}
	public static void main(String[] args) {
		Client2 client = new Client2();
	}

}

【最终效果展示】
我打开了一个服务器端，3个客户端。任何一个客户端发送消息，其他客户端都可以收到。Done！