Java NIO实战之聊天室

在工作之余花了两个星期看完了《Java NIO》。整体来说这本书把NIO写的非常具体，没有过多的废话，讲的都是重点，仅仅是翻译的中文版看的确实吃力。英文水平太低也没办法，总算也坚持看完了。《Java NIO》这本书的重点在于第四章解说的“选择器”，要理解透还是要重复琢磨推敲。愚钝的我花了大概3天的时间才将NIO的选择器机制理解透并能较熟练的运用。于是便写了这个聊天室程序。

以下直接上代码。jdk1.5以上经过測试，能够支持多人同一时候在线聊天；

将下面代码拷贝到项目中便可执行。源代码下载地址：聊天室源代码

一、server端

package com.chat.server;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Iterator;
import java.util.Vector;

/**
 * 聊天室:服务端
 * @author zing
 *
 */
public class ChatServer implements Runnable {

	//选择器
	private Selector selector;
	//注冊ServerSocketChannel后的选择键
	private SelectionKey serverKey;
	//标识是否执行
	private boolean isRun;
	//当前聊天室中的username称列表
	private Vector<String> unames;
	//时间格式化器
	SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

	/**
	 * 构造函数
	 * @param port 服务端监控的端口号
	 */
	public ChatServer(int port) {
		isRun = true;
		unames = new Vector<String>();
		init(port);
	}

	/**
	 * 初始化选择器和服务器套接字
	 *
	 * @param port 服务端监控的端口号
	 */
	private void init(int port) {
		try {
			//获得选择器实例
			selector = Selector.open();
			//获得服务器套接字实例
			ServerSocketChannel serverChannel = ServerSocketChannel.open();
			//绑定端口号
			serverChannel.socket().bind(new InetSocketAddress(port));
			//设置为非堵塞
			serverChannel.configureBlocking(false);
			//将ServerSocketChannel注冊到选择器，指定其行为为"等待接受连接"
			serverKey = serverChannel.register(selector, SelectionKey.OP_ACCEPT);
			printInfo("server starting...");
		} catch (IOException e) {
			e.printStackTrace();
		}

	}

	@Override
	public void run() {
		try {
			//轮询选择器选择键
			while (isRun) {
				//选择一组已准备进行IO操作的通道的key，等于1时表示有这种key
				int n = selector.select();
				if (n > 0) {
					//从选择器上获取已选择的key的集合并进行迭代
					Iterator<SelectionKey> iter = selector.selectedKeys().iterator();
					while (iter.hasNext()) {
						SelectionKey key = iter.next();
						//若此key的通道是等待接受新的套接字连接
						if (key.isAcceptable()) {
							//记住一定要remove这个key，否则之后的新连接将被堵塞无法连接服务器
							iter.remove();
							//获取key相应的通道
							ServerSocketChannel serverChannel = (ServerSocketChannel) key.channel();
							//接受新的连接返回和client对等的套接字通道
							SocketChannel channel = serverChannel.accept();
							if (channel == null) {
								continue;
							}
							//设置为非堵塞
							channel.configureBlocking(false);
							//将这个套接字通道注冊到选择器，指定其行为为"读"
							channel.register(selector, SelectionKey.OP_READ);
						}
						//若此key的通道的行为是"读"
						if (key.isReadable()) {
							readMsg(key);
						}
						//若次key的通道的行为是"写"
						if (key.isWritable()) {
							writeMsg(key);
						}
					}
				}
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	/**
	 * 从key相应的套接字通道上读数据
	 * @param key 选择键
	 * @throws IOException
	 */
	private void readMsg(SelectionKey key) throws IOException {
		//获取此key相应的套接字通道
		SocketChannel channel = (SocketChannel) key.channel();
		//创建一个大小为1024k的缓存区
		ByteBuffer buffer = ByteBuffer.allocate(1024);
		StringBuffer sb = new StringBuffer();
		//将通道的数据读到缓存区
		int count = channel.read(buffer);
		if (count > 0) {
			//翻转缓存区(将缓存区由写进数据模式变成读出数据模式)
			buffer.flip();
			//将缓存区的数据转成String
			sb.append(new String(buffer.array(), 0, count));
		}
		String str = sb.toString();
		//若消息中有"open_"，表示client准备进入聊天界面
		//client传过来的数据格式是"open_zing"，表示名称为zing的用户请求打开聊天窗口
		//username称列表有更新，则应将username称数据写给每个已连接的client
		if (str.indexOf("open_") != -1) {//client连接服务器
			String name = str.substring(5);
			printInfo(name + " online");
			unames.add(name);
			//获取选择器已选择的key并迭代
			Iterator<SelectionKey> iter = selector.selectedKeys().iterator();
			while (iter.hasNext()) {
				SelectionKey selKey = iter.next();
				//若不是服务器套接字通道的key，则将数据设置到此key中
				//并更新此key感兴趣的动作
				if (selKey != serverKey) {
					selKey.attach(unames);
					selKey.interestOps(selKey.interestOps() | SelectionKey.OP_WRITE);
				}
			}
		} else if (str.indexOf("exit_") != -1) {// client发送退出命令
			String uname = str.substring(5);
			//删除此username称
			unames.remove(uname);
			//将"close"字符串附加到key
			key.attach("close");
			//更新此key感兴趣的动作
			key.interestOps(SelectionKey.OP_WRITE);
			//获取选择器上的已选择的key并迭代
			//将更新后的名称列表数据附加到每个套接字通道key上,并重设key感兴趣的操作
			Iterator<SelectionKey> iter = key.selector().selectedKeys().iterator();
			while (iter.hasNext()) {
				SelectionKey selKey = iter.next();
				if (selKey != serverKey && selKey != key) {
					selKey.attach(unames);
					selKey.interestOps(selKey.interestOps() | SelectionKey.OP_WRITE);
				}
			}
			printInfo(uname + " offline");
		} else {// 读取client聊天消息
			String uname = str.substring(0, str.indexOf("^"));
			String msg = str.substring(str.indexOf("^") + 1);
			printInfo("("+uname+")说：" + msg);
			String dateTime = sdf.format(new Date());
			String smsg = uname + " " + dateTime + "\n  " + msg + "\n";
			Iterator<SelectionKey> iter = selector.selectedKeys().iterator();
			while (iter.hasNext()) {
				SelectionKey selKey = iter.next();
				if (selKey != serverKey) {
					selKey.attach(smsg);
					selKey.interestOps(selKey.interestOps() | SelectionKey.OP_WRITE);
				}
			}
		}
	}

	/**
	 * 写数据到key相应的套接字通道
	 * @param key
	 * @throws IOException
	 */
	private void writeMsg(SelectionKey key) throws IOException {
		SocketChannel channel = (SocketChannel) key.channel();
		Object obj = key.attachment();
		//这里必要要将key的附加数据设置为空。否则会有问题
		key.attach("");
		//附加值为"close"，则取消此key，并关闭相应通道
		if (obj.toString().equals("close")) {
			key.cancel();
			channel.socket().close();
			channel.close();
			return;
		}else {
			//将数据写到通道
			channel.write(ByteBuffer.wrap(obj.toString().getBytes()));
		}
		//重设此key兴趣
		key.interestOps(SelectionKey.OP_READ);
	}

	private void printInfo(String str) {
		System.out.println("[" + sdf.format(new Date()) + "] -> " + str);
	}

	public static void main(String[] args) {
		ChatServer server = new ChatServer(19999);
		new Thread(server).start();
	}
}

二、client

1、服务类。用于与服务端交互

package com.chat.client;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;

public class ClientService {
	private static final String HOST = "127.0.0.1";
	private static final int PORT = 19999;
	private static SocketChannel sc;

	private static Object lock = new Object();

	private static ClientService service;

	public static ClientService getInstance(){
		synchronized (lock) {
			if(service == null){
				try {
					service = new ClientService();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return service;
		}
	}

	private ClientService() throws IOException {
		sc = SocketChannel.open();
		sc.configureBlocking(false);
		sc.connect(new InetSocketAddress(HOST, PORT));
	}

	public void sendMsg(String msg) {
		try {
			while (!sc.finishConnect()) {
			}
			sc.write(ByteBuffer.wrap(msg.getBytes()));
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public String receiveMsg() {
		ByteBuffer buffer = ByteBuffer.allocate(1024);
		buffer.clear();
		StringBuffer sb = new StringBuffer();
		int count = 0;
		String msg = null;
		try {
			while ((count = sc.read(buffer)) > 0) {
				sb.append(new String(buffer.array(), 0, count));
			}
			if (sb.length() > 0) {
				msg = sb.toString();
				if ("close".equals(sb.toString())) {
					msg = null;
					sc.close();
					sc.socket().close();
				}
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		return msg;
	}

}

2、登陆窗口，用户设置名称

package com.chat.client;

import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

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

/**
 * 设置名称窗口
 *
 * @author zing
 *
 */
public class SetNameFrame extends JFrame {
	private static final long serialVersionUID = 1L;
	private static JTextField txtName;// 文本框
	private static JButton btnOK;// okbutton
	private static JLabel label;// 标签

	public SetNameFrame() {
		this.setLayout(null);
		Toolkit kit = Toolkit.getDefaultToolkit();
		int w = kit.getScreenSize().width;
		int h = kit.getScreenSize().height;
		this.setBounds(w / 2 - 230 / 2, h / 2 - 200 / 2, 230, 200);
		this.setTitle("设置名称");
		this.setDefaultCloseOperation(EXIT_ON_CLOSE);
		this.setResizable(false);
		txtName = new JTextField(4);
		this.add(txtName);
		txtName.setBounds(10, 10, 100, 25);
		btnOK = new JButton("OK");
		this.add(btnOK);
		btnOK.setBounds(120, 10, 80, 25);
		label = new JLabel("[w:" + w + ",h:" + h + "]");
		this.add(label);
		label.setBounds(10, 40, 200, 100);
		label.setText("<html>在上面的文本框中输入名字<br/>显示器宽度：" + w + "<br/>显示器高度：" + h
				+ "</html>");

		btnOK.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				String uname = txtName.getText();
				ClientService service = ClientService.getInstance();
				ChatFrame chatFrame = new ChatFrame(service, uname);
				chatFrame.show();
				setVisible(false);
			}
		});
	}

	public static void main(String[] args) {
		SetNameFrame setNameFrame = new SetNameFrame();
		setNameFrame.setVisible(true);
	}

}

3、聊天室窗口

package com.chat.client;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

/**
 * 聊天室窗口
 * @author zing
 *
 */
public class ChatFrame {

	private JTextArea readContext = new JTextArea(18, 30);// 显示消息文本框
	private JTextArea writeContext = new JTextArea(6, 30);// 发送消息文本框

	private DefaultListModel modle = new DefaultListModel();// 用户列表模型
	private JList list = new JList(modle);// 用户列表

	private JButton btnSend = new JButton("发送");// 发送消息button
	private JButton btnClose = new JButton("关闭");// 关闭聊天窗口button

	private JFrame frame = new JFrame("ChatFrame");// 窗口界面

	private String uname;// 用户姓名

	private ClientService service;// 用于与server交互

	private boolean isRun = false;// 是否执行

	public ChatFrame(ClientService service, String uname) {
		this.isRun = true;
		this.uname = uname;
		this.service = service;
	}

	// 初始化界面控件及事件
	private void init() {
		frame.setLayout(null);
		frame.setTitle(uname + " 聊天窗口");
		frame.setSize(500, 500);
		frame.setLocation(400, 200);
		//设置可关闭
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		//不能改变窗口大小
		frame.setResizable(false);
		//聊天消息显示区带滚动栏
		JScrollPane readScroll = new JScrollPane(readContext);
		readScroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
		frame.add(readScroll);
		//消息编辑区带滚动栏
		JScrollPane writeScroll = new JScrollPane(writeContext);
		writeScroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
		frame.add(writeScroll);
		frame.add(list);
		frame.add(btnSend);
		frame.add(btnClose);
		readScroll.setBounds(10, 10, 320, 300);
		readContext.setBounds(0, 0, 320, 300);
		readContext.setEditable(false);//设置为不可编辑
		readContext.setLineWrap(true);// 自己主动换行
		writeScroll.setBounds(10, 315, 320, 100);
		writeContext.setBounds(0, 0, 320, 100);
		writeContext.setLineWrap(true);// 自己主动换行
		list.setBounds(340, 10, 140, 445);
		btnSend.setBounds(150, 420, 80, 30);
		btnClose.setBounds(250, 420, 80, 30);
		//窗口关闭事件
		frame.addWindowListener(new WindowAdapter() {
			@Override
			public void windowClosing(WindowEvent e) {
				isRun = false;
				service.sendMsg("exit_" + uname);
				System.exit(0);
			}
		});

		//发送button事件
		btnSend.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				String msg = writeContext.getText().trim();
				if(msg.length() > 0){
					service.sendMsg(uname + "^" + writeContext.getText());
				}
				//发送消息后，去掉编辑区文本。并获得光标焦点
				writeContext.setText(null);
				writeContext.requestFocus();
			}
		});

		//关闭button事件
		btnClose.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				isRun = false;
				service.sendMsg("exit_" + uname);
				System.exit(0);
			}
		});

		//右边名称列表选择事件
		list.addListSelectionListener(new ListSelectionListener() {
			@Override
			public void valueChanged(ListSelectionEvent e) {
				// JOptionPane.showMessageDialog(null,
				// list.getSelectedValue().toString());
			}
		});

		//消息编辑区键盘按键事件
		writeContext.addKeyListener(new KeyListener() {

			@Override
			public void keyTyped(KeyEvent e) {
				// TODO Auto-generated method stub

			}

			//按下键盘按键后释放
			@Override
			public void keyReleased(KeyEvent e) {
				//按下enter键发送消息
				if(e.getKeyCode() == KeyEvent.VK_ENTER){
					String msg = writeContext.getText().trim();
					if(msg.length() > 0){
						service.sendMsg(uname + "^" + writeContext.getText());
					}
					writeContext.setText(null);
					writeContext.requestFocus();
				}
			}

			@Override
			public void keyPressed(KeyEvent e) {
				// TODO Auto-generated method stub

			}
		});
	}

	// 此线程类用于轮询读取server发送的消息
	private class MsgThread extends Thread {
		@Override
		public void run() {
			while (isRun) {
				String msg = service.receiveMsg();
				if (msg != null) {
					//若是名称列表数据，则更新聊天窗口右边的列表
					if (msg.indexOf("[") != -1 && msg.lastIndexOf("]") != -1) {
						msg = msg.substring(1, msg.length() - 1);
						String[] userNames = msg.split(",");
						modle.removeAllElements();
						for (int i = 0; i < userNames.length; i++) {
							modle.addElement(userNames[i].trim());
						}
					} else {
						//将聊天数据设置到聊天消息显示区
						String str = readContext.getText() + msg;
						readContext.setText(str);
						readContext.selectAll();//保持滚动栏在最以下
					}
				}
			}
		}
	}

	// 显示界面
	public void show() {
		this.init();
		service.sendMsg("open_" + uname);
		MsgThread msgThread = new MsgThread();
		msgThread.start();
		this.frame.setVisible(true);
	}
}