本文例項講述了Java NIO實戰之聊天室功能。分享給大家供大家參考，具體如下：

在工作之餘花了兩個星期看完了《Java NIO》，總體來說這本書把NIO寫的很詳細，沒有過多的廢話，講的都是重點，只是翻譯的中文版看的確實吃力，英文水平太低也沒辦法，總算也堅持看完了。《Java NIO》這本書的重點在於第四章講解的“選擇器”，要理解透還是要反覆琢磨推敲；愚鈍的我花了大概3天的時間才將NIO的選擇器機制理解透並能較熟練的運用，於是便寫了這個聊天室程式。

下面直接上程式碼，jdk1.5以上經過測試，可以支援多人同時線上聊天；

將以下程式碼複製到專案中便可執行，原始碼下載地址：聊天室原始碼。

一、伺服器端

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:服務端
 * @author zing
 * 
 */
public class ChatServer implements Runnable {
    //選擇器
    private Selector selector;
    //註冊ServerSocketChannel後的選擇鍵
    private SelectionKey serverKey;
    //標識是否執行
    private boolean isRun;
    //當前聊天室中的使用者名稱稱列表
    private Vector<String> unames;
    //時間格式化器
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    /**
     * 建構函式
     * @param port 服務端監控的埠號
     */
    public ChatServer(int port) {
        isRun = true;
        unames = new Vector<String>();
        init(port);
    }
    /**
     * 初始化選擇器和伺服器套接字
     * 
     * @param port 服務端監控的埠號
     */
    private void init(int port) {
        try {
            //獲得選擇器例項
            selector = Selector.open();
            //獲得伺服器套接字例項
            ServerSocketChannel serverChannel = ServerSocketChannel.open();
            //繫結埠號
            serverChannel.socket().bind(new InetSocketAddress(port));
            //設定為非阻塞
            serverChannel.configureBlocking(false);
            //將ServerSocketChannel註冊到選擇器，指定其行為為"等待接受連線"
            serverKey = serverChannel.register(selector,SelectionKey.OP_ACCEPT);
            printInfo("server starting...");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    @Override
    public void run() {
        try {
            //輪詢選擇器選擇鍵
            while (isRun) {
                //選擇一組已準備進行IO操作的通道的key，等於1時表示有這樣的key
                int n = selector.select();
                if (n > 0) {
                    //從選擇器上獲取已選擇的key的集合並進行迭代
                    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連線
                        if (key.isAcceptable()) {
                            //記住一定要remove這個key，否則之後的新連線將被阻塞無法連線伺服器
                            iter.remove();
                            //獲取key對應的通道
                            ServerSocketChannel serverChannel = (ServerSocketChannel) key.channel();
                            //接受新的連線返回和客戶端對等的套接字通道
                            SocketChannel channel = serverChannel.accept();
                            if (channel == null) {
                                continue;
                            }
                            //設定為非阻塞
                            channel.configureBlocking(false);
                            //將這個套接字通道註冊到選擇器，指定其行為為"讀"
                            channel.register(selector,SelectionKey.OP_READ);
                        }
                        //若此key的通道的行為是"讀"
                        if (key.isReadable()) {
                            readMsg(key);
                        }
                        //若次key的通道的行為是"寫"
                        if (key.isWritable()) {
                            writeMsg(key);
                        }
                    }
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /**
     * 從key對應的套接字通道上讀資料
     * @param key 選擇鍵
     * @throws IOException
     */
    private void readMsg(SelectionKey key) throws IOException {
        //獲取此key對應的套接字通道
        SocketChannel channel = (SocketChannel) key.channel();
        //建立一個大小為1024k的快取區
        ByteBuffer buffer = ByteBuffer.allocate(1024);
        StringBuffer sb = new StringBuffer();
        //將通道的資料讀到快取區
        int count = channel.read(buffer);
        if (count > 0) {
            //翻轉快取區(將快取區由寫進資料模式變成讀出資料模式)
            buffer.flip();
            //將快取區的資料轉成String
            sb.append(new String(buffer.array(),count));
        }
        String str = sb.toString();
        //若訊息中有"open_"，表示客戶端準備進入聊天介面
        //客戶端傳過來的資料格式是"open_zing"，表示名稱為zing的使用者請求開啟聊天窗體
        //使用者名稱稱列表有更新，則應將使用者名稱稱資料寫給每一個已連線的客戶端
        if (str.indexOf("open_") != -1) {//客戶端連線伺服器
            String name = str.substring(5);
            printInfo(name + " online");
            unames.add(name);
            //獲取選擇器已選擇的key並迭代
            Iterator<SelectionKey> iter = selector.selectedKeys().iterator();
            while (iter.hasNext()) {
                SelectionKey selKey = iter.next();
                //若不是伺服器套接字通道的key，則將資料設定到此key中
                //並更新此key感興趣的動作
                if (selKey != serverKey) {
                    selKey.attach(unames);
                    selKey.interestOps(selKey.interestOps() | SelectionKey.OP_WRITE);
                }
            }
        } else if (str.indexOf("exit_") != -1) {// 客戶端傳送退出命令
            String uname = str.substring(5);
            //刪除此使用者名稱稱
            unames.remove(uname);
            //將"close"字串附加到key
            key.attach("close");
            //更新此key感興趣的動作
            key.interestOps(SelectionKey.OP_WRITE);
            //獲取選擇器上的已選擇的key並迭代
            //將更新後的名稱列表資料附加到每個套接字通道key上,並重設key感興趣的操作
            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 {// 讀取客戶端聊天訊息
            String uname = str.substring(0,str.indexOf("^"));
            String msg = str.substring(str.indexOf("^") + 1);
            printInfo("("+uname+")說：" + 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);
                }
            }
        }
    }
    /**
     * 寫資料到key對應的套接字通道
     * @param key
     * @throws IOException
     */
    private void writeMsg(SelectionKey key) throws IOException {
        SocketChannel channel = (SocketChannel) key.channel();
        Object obj = key.attachment();
        //這裡必要要將key的附加資料設定為空，否則會有問題
        key.attach("");
        //附加值為"close"，則取消此key，並關閉對應通道
        if (obj.toString().equals("close")) {
            key.cancel();
            channel.socket().close();
            channel.close();
            return;
        }else {
            //將資料寫到通道
            channel.write(ByteBuffer.wrap(obj.toString().getBytes()));
        }
        //重設此key興趣
        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、客戶端

1、服務類，用於與服務端互動

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(),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、登陸窗體，使用者設定名稱

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;
/**
 * 設定名稱窗體
 * 
 * @author zing
 * 
 */
public class SetNameFrame extends JFrame {
    private static final long serialVersionUID = 1L;
    private static JTextField txtName;// 文字框
    private static JButton btnOK;// ok按鈕
    private static JLabel label;// 標籤
    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("設定名稱");
        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(120,80,25);
        label = new JLabel("[w:" + w + ",h:" + h + "]");
        this.add(label);
        label.setBounds(10,40,200,100);
        label.setText("<html>在上面的文字框中輸入名字<br/>顯示器寬度：" + w + "<br/>顯示器高度：" + 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、聊天室窗體

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;
/**
 * 聊天室窗體
 * @author zing
 *
 */
public class ChatFrame {
    private JTextArea readContext = new JTextArea(18,30);// 顯示訊息文字框
    private JTextArea writeContext = new JTextArea(6,30);// 傳送訊息文字框
    private DefaultListModel modle = new DefaultListModel();// 使用者列表模型
    private JList list = new JList(modle);// 使用者列表
    private JButton btnSend = new JButton("傳送");// 傳送訊息按鈕
    private JButton btnClose = new JButton("關閉");// 關閉聊天視窗按鈕
    private JFrame frame = new JFrame("ChatFrame");// 窗體介面
    private String uname;// 使用者姓名
    private ClientService service;// 用於與伺服器互動
    private boolean isRun = false;// 是否執行
    public ChatFrame(ClientService service,String uname) {
        this.isRun = true;
        this.uname = uname;
        this.service = service;
    }
    // 初始化介面控制元件及事件
    private void init() {
        frame.setLayout(null);
        frame.setTitle(uname + " 聊天視窗");
        frame.setSize(500,500);
        frame.setLocation(400,200);
        //設定可關閉
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //不能改變窗體大小
        frame.setResizable(false);
        //聊天訊息顯示區帶滾動條
        JScrollPane readScroll = new JScrollPane(readContext);
        readScroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
        frame.add(readScroll);
        //訊息編輯區帶滾動條
        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(10,320,300);
        readContext.setBounds(0,300);
        readContext.setEditable(false);//設定為不可編輯
        readContext.setLineWrap(true);// 自動換行
        writeScroll.setBounds(10,315,100);
        writeContext.setBounds(0,100);
        writeContext.setLineWrap(true);// 自動換行
        list.setBounds(340,140,445);
        btnSend.setBounds(150,420,30);
        btnClose.setBounds(250,30);
        //窗體關閉事件
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                isRun = false;
                service.sendMsg("exit_" + uname);
                System.exit(0);
            }
        });
        //傳送按鈕事件
        btnSend.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String msg = writeContext.getText().trim();
                if(msg.length() > 0){
                    service.sendMsg(uname + "^" + writeContext.getText());
                }
                //傳送訊息後，去掉編輯區文字，並獲得游標焦點
                writeContext.setText(null);
                writeContext.requestFocus();
            }
        });
        //關閉按鈕事件
        btnClose.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                isRun = false;
                service.sendMsg("exit_" + uname);
                System.exit(0);
            }
        });
        //右邊名稱列表選擇事件
        list.addListSelectionListener(new ListSelectionListener() {
            @Override
            public void valueChanged(ListSelectionEvent e) {
                // JOptionPane.showMessageDialog(null,// list.getSelectedValue().toString());
            }
        });
        //訊息編輯區鍵盤按鍵事件
        writeContext.addKeyListener(new KeyListener() {
            @Override
            public void keyTyped(KeyEvent e) {
                // TODO Auto-generated method stub
            }
            //按下鍵盤按鍵後釋放
            @Override
            public void keyReleased(KeyEvent e) {
                //按下enter鍵傳送訊息
                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
            }
        });
    }
    // 此執行緒類用於輪詢讀取伺服器傳送的訊息
    private class MsgThread extends Thread {
        @Override
        public void run() {
            while (isRun) {
                String msg = service.receiveMsg();
                if (msg != null) {
                    //若是名稱列表資料，則更新聊天窗體右邊的列表
                    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 {
                        //將聊天資料設定到聊天訊息顯示區
                        String str = readContext.getText() + msg;
                        readContext.setText(str);
                        readContext.selectAll();//保持滾動條在最下面
                    }
                }
            }
        }
    }
    // 顯示介面
    public void show() {
        this.init();
        service.sendMsg("open_" + uname);
        MsgThread msgThread = new MsgThread();
        msgThread.start();
        this.frame.setVisible(true);
    }
}

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希望本文所述對大家java程式設計有所幫助。