Java NIO实战之聊天室功能详解

发布时间：2020-09-11 08:13:41 作者：my_codeONE
来源：脚本之家阅读：211

本文实例讲述了Java NIO实战之聊天室功能。分享给大家供大家参考，具体如下：

在工作之余花了两个星期看完了《Java NIO》，总体来说这本书把NIO写的很详细，没有过多的废话，讲的都是重点，只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讲解的“选择器”，要理解透还是要反复琢磨推敲；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。

下面直接上代码，jdk1.5以上经过测试，可以支持多人同时在线聊天；

将以下代码复制到项目中便可运行，源码下载地址：聊天室源码。

一、服务器端

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;
    //注册ServerSocketChannel后的选择键
    private SelectionKey serverKey;
    //标识是否运行
    private boolean isRun;
    //当前聊天室中的用户名称列表
    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));
            //设置为非阻塞
            serverChannel.configureBlocking(false);
            //将ServerSocketChannel注册到选择器，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时表示有这样的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阻塞无法连接服务器
                            iter.remove();
                            //获取key对应的通道
                            ServerSocketChannel serverChannel = (ServerSocketChannel) key.channel();
                            //接受新的连接返回和客户端对等的套接字通道
                            SocketChannel channel = serverChannel.accept();
                            if (channel == null) {
                                continue;
                            }
                            //设置为非阻塞
                            channel.configureBlocking(false);
                            //将这个套接字通道注册到选择器，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对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对应的套接字通道
        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_"，表示客户端准备进入聊天界面
        //客户端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体
        //用户名称列表有更新，则应将用户名称数据写给每一个已连接的客户端
        if (str.indexOf("open_") != -1) {//客户端连接服务器
            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) {// 客户端发送退出命令
            String uname = str.substring(5);
            //删除此用户名称
            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 {// 读取客户端聊天消息
            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对应的套接字通道
     * @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，并关闭对应通道
        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、客户端

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、登陆窗体，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;
/**
 * 设置名称窗体
 * 
 * @author zing
 * 
 */
public class SetNameFrame extends JFrame {
    private static final long serialVersionUID = 1L;
    private static JTextField txtName;// 文本框
    private static JButton btnOK;// ok按钮
    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、聊天室窗体

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;
/**
 * 聊天室窗体
 * @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");// 发送消息按钮
    private JButton btnClose = new JButton("关闭");// 关闭聊天窗口按钮
    private JFrame frame = new JFrame("ChatFrame");// 窗体界面
    private String uname;// 用户姓名
    private ClientService service;// 用于与服务器交互
    private boolean isRun = false;// 是否运行
    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);
        //不能改变窗体大小
        frame.setResizable(false);
        //聊天消息显示区带滚动条
        JScrollPane readScroll = new JScrollPane(readContext);
        readScroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
        frame.add(readScroll);
        //消息编辑区带滚动条
        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);// 自动换行
        writeScroll.setBounds(10, 315, 320, 100);
        writeContext.setBounds(0, 0, 320, 100);
        writeContext.setLineWrap(true);// 自动换行
        list.setBounds(340, 10, 140, 445);
        btnSend.setBounds(150, 420, 80, 30);
        btnClose.setBounds(250, 420, 80, 30);
        //窗体关闭事件
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                isRun = false;
                service.sendMsg("exit_" + uname);
                System.exit(0);
            }
        });
        //发送按钮事件
        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();
            }
        });
        //关闭按钮事件
        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服务器发送的消息
    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，则更新聊天窗体右边的列表
                    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();//保持滚动条在最下面
                    }
                }
            }
        }
    }
    // 显示界面
    public void show() {
        this.init();
        service.sendMsg("open_" + uname);
        MsgThread msgThread = new MsgThread();
        msgThread.start();
        this.frame.setVisible(true);
    }
}

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Java NIO实战之聊天室功能详解

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