Java NIO示例：多人网络聊天室

一个多客户端聊天室，支持多客户端聊天，有如下功能：

• 功能1： 客户端通过Java NIO连接到服务端，支持多客户端的连接
• 功能2：客户端初次连接时，服务端提示输入昵称，如果昵称已经有人使用，提示重新输入，如果昵称唯一，则登录成功，之后发送消息都需要按照规定格式带着昵称发送消息
• 功能3：客户端登录后，发送已经设置好的欢迎信息和在线人数给客户端，并且通知其他客户端该客户端上线
• 功能4：服务器收到已登录客户端输入内容，转发至其他登录客户端。
• 功能5 TODO：客户端下线检测  方案是：客户端在线的时候发送心跳，服务端用TimeCacheMap自动删除过期对象，同时通知线上用户删掉的用户下线。

下面演示下效果，代码见附录！

 

启动服务器，监听某个端口

服务器console

Server is listening now...

 

启动一个客户端，连接服务器

服务器console

Server is listening now...Server is listening from client :/127.0.0.1:50206

客户端console

Please input your name.

 

客户端输入一个昵称

服务端console

Server is listening now...Server is listening from client :/127.0.0.1:50206Server is listening from client /127.0.0.1:50206 data rev is: byr1#@#

客户端console

Please input your name.byr1welcome byr1 to chat room! Online numbers:1

 

再启动另外一个客户端，并输入昵称

服务端console

Server is listening now...Server is listening from client :/127.0.0.1:50206Server is listening from client /127.0.0.1:50206 data rev is: byr1#@#Server is listening from client :/127.0.0.1:50261Server is listening from client /127.0.0.1:50261 data rev is: byr2#@#

客户端byr1 console

Please input your name.byr1welcome byr1 to chat room! Online numbers:1welcome byr2 to chat room! Online numbers:2

客户端byr2 console

Please input your name.byr2welcome byr2 to chat room! Online numbers:2

 

客户端byr1发送一个消息，客户byr2回一条消息

服务端console

Server is listening now...Server is listening from client :/127.0.0.1:50206Server is listening from client /127.0.0.1:50206 data rev is: byr1#@#Server is listening from client :/127.0.0.1:50261Server is listening from client /127.0.0.1:50261 data rev is: byr2#@#Server is listening from client /127.0.0.1:50206 data rev is: byr1#@#hello byr2, a nice day, isn't it?Server is listening from client /127.0.0.1:50261 data rev is: byr2#@#fine

客户端byr1 console

Please input your name.byr1welcome byr1 to chat room! Online numbers:1welcome byr2 to chat room! Online numbers:2hello byr2, a nice day, isn't it?byr2 say fine

客户端byr2 console

Please input your name.byr2welcome byr2 to chat room! Online numbers:2byr1 say hello byr2, a nice day, isn't it?fine

 

附录：server和client代码

server代码

package com.huahuiyang.channel;import java.io.IOException;import java.net.InetSocketAddress;import java.nio.ByteBuffer;import java.nio.channels.Channel;import java.nio.channels.SelectionKey;import java.nio.channels.Selector;import java.nio.channels.ServerSocketChannel;import java.nio.channels.SocketChannel;import java.nio.charset.Charset;import java.util.HashSet;import java.util.Iterator;import java.util.Set;/** * 网络多客户端聊天室 * 功能1： 客户端通过Java NIO连接到服务端，支持多客户端的连接 * 功能2：客户端初次连接时，服务端提示输入昵称，如果昵称已经有人使用，提示重新输入，如果昵称唯一，则登录成功，之后发送消息都需要按照规定格式带着昵称发送消息 * 功能3：客户端登录后，发送已经设置好的欢迎信息和在线人数给客户端，并且通知其他客户端该客户端上线 * 功能4：服务器收到已登录客户端输入内容，转发至其他登录客户端。 *  * TODO 客户端下线检测 */public class ChatRoomServer {    private Selector selector = null;    static final int port = 9999;    private Charset charset = Charset.forName("UTF-8");    //用来记录在线人数，以及昵称    private static HashSet<String> users = new HashSet<String>();        private static String USER_EXIST = "system message: user exist, please change a name";    //相当于自定义协议格式，与客户端协商好    private static String USER_CONTENT_SPILIT = "#@#";        private static boolean flag = false;        public void init() throws IOException    {        selector = Selector.open();        ServerSocketChannel server = ServerSocketChannel.open();        server.bind(new InetSocketAddress(port));        //非阻塞的方式        server.configureBlocking(false);        //注册到选择器上，设置为监听状态        server.register(selector, SelectionKey.OP_ACCEPT);                System.out.println("Server is listening now...");                while(true) {            int readyChannels = selector.select();            if(readyChannels == 0) continue;             Set selectedKeys = selector.selectedKeys();  //可以通过这个方法，知道可用通道的集合            Iterator keyIterator = selectedKeys.iterator();            while(keyIterator.hasNext()) {                 SelectionKey sk = (SelectionKey) keyIterator.next();                 keyIterator.remove();                 dealWithSelectionKey(server,sk);            }        }    }        public void dealWithSelectionKey(ServerSocketChannel server,SelectionKey sk) throws IOException {        if(sk.isAcceptable())        {            SocketChannel sc = server.accept();            //非阻塞模式            sc.configureBlocking(false);            //注册选择器，并设置为读取模式，收到一个连接请求，然后起一个SocketChannel，并注册到selector上，之后这个连接的数据，就由这个SocketChannel处理            sc.register(selector, SelectionKey.OP_READ);                        //将此对应的channel设置为准备接受其他客户端请求            sk.interestOps(SelectionKey.OP_ACCEPT);            System.out.println("Server is listening from client :" + sc.getRemoteAddress());            sc.write(charset.encode("Please input your name."));        }        //处理来自客户端的数据读取请求        if(sk.isReadable())        {            //返回该SelectionKey对应的 Channel，其中有数据需要读取            SocketChannel sc = (SocketChannel)sk.channel();             ByteBuffer buff = ByteBuffer.allocate(1024);            StringBuilder content = new StringBuilder();            try            {                while(sc.read(buff) > 0)                {                    buff.flip();                    content.append(charset.decode(buff));                                    }                System.out.println("Server is listening from client " + sc.getRemoteAddress() + " data rev is: " + content);                //将此对应的channel设置为准备下一次接受数据                sk.interestOps(SelectionKey.OP_READ);            }            catch (IOException io)            {                sk.cancel();                if(sk.channel() != null)                {                    sk.channel().close();                }            }            if(content.length() > 0)            {                String[] arrayContent = content.toString().split(USER_CONTENT_SPILIT);                //注册用户                if(arrayContent != null && arrayContent.length ==1) {                    String name = arrayContent[0];                    if(users.contains(name)) {                        sc.write(charset.encode(USER_EXIST));                                            } else {                        users.add(name);                        int num = OnlineNum(selector);                        String message = "welcome "+name+" to chat room! Online numbers:"+num;                        BroadCast(selector, null, message);                    }                }                 //注册完了，发送消息                else if(arrayContent != null && arrayContent.length >1){                    String name = arrayContent[0];                    String message = content.substring(name.length()+USER_CONTENT_SPILIT.length());                    message = name + " say " + message;                    if(users.contains(name)) {                        //不回发给发送此内容的客户端                        BroadCast(selector, sc, message);                    }                }            }                    }    }        //TODO 要是能检测下线，就不用这么统计了    public static int OnlineNum(Selector selector) {        int res = 0;        for(SelectionKey key : selector.keys())        {            Channel targetchannel = key.channel();                        if(targetchannel instanceof SocketChannel)            {                res++;            }        }        return res;    }        public void BroadCast(Selector selector, SocketChannel except, String content) throws IOException {        //广播数据到所有的SocketChannel中        for(SelectionKey key : selector.keys())        {            Channel targetchannel = key.channel();            //如果except不为空，不回发给发送此内容的客户端            if(targetchannel instanceof SocketChannel && targetchannel!=except)            {                SocketChannel dest = (SocketChannel)targetchannel;                dest.write(charset.encode(content));            }        }    }        public static void main(String[] args) throws IOException     {        new ChatRoomServer().init();    }}

 

client代码

package com.huahuiyang.channel;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.SocketChannel;import java.nio.charset.Charset;import java.util.Iterator;import java.util.Scanner;import java.util.Set;public class ChatRoomClient {    private Selector selector = null;    static final int port = 9999;    private Charset charset = Charset.forName("UTF-8");    private SocketChannel sc = null;    private String name = "";    private static String USER_EXIST = "system message: user exist, please change a name";    private static String USER_CONTENT_SPILIT = "#@#";        public void init() throws IOException    {        selector = Selector.open();        //连接远程主机的IP和端口        sc = SocketChannel.open(new InetSocketAddress("127.0.0.1",port));        sc.configureBlocking(false);        sc.register(selector, SelectionKey.OP_READ);        //开辟一个新线程来读取从服务器端的数据        new Thread(new ClientThread()).start();        //在主线程中 从键盘读取数据输入到服务器端        Scanner scan = new Scanner(System.in);        while(scan.hasNextLine())        {            String line = scan.nextLine();            if("".equals(line)) continue; //不允许发空消息            if("".equals(name)) {                name = line;                line = name+USER_CONTENT_SPILIT;            } else {                line = name+USER_CONTENT_SPILIT+line;            }            sc.write(charset.encode(line));//sc既能写也能读，这边是写        }            }    private class ClientThread implements Runnable    {        public void run()        {            try            {                while(true) {                    int readyChannels = selector.select();                    if(readyChannels == 0) continue;                     Set selectedKeys = selector.selectedKeys();  //可以通过这个方法，知道可用通道的集合                    Iterator keyIterator = selectedKeys.iterator();                    while(keyIterator.hasNext()) {                         SelectionKey sk = (SelectionKey) keyIterator.next();                         keyIterator.remove();                         dealWithSelectionKey(sk);                    }                }            }            catch (IOException io)            {}        }        private void dealWithSelectionKey(SelectionKey sk) throws IOException {            if(sk.isReadable())            {                //使用 NIO 读取 Channel中的数据，这个和全局变量sc是一样的，因为只注册了一个SocketChannel                //sc既能写也能读，这边是读                SocketChannel sc = (SocketChannel)sk.channel();                                ByteBuffer buff = ByteBuffer.allocate(1024);                String content = "";                while(sc.read(buff) > 0)                {                    buff.flip();                    content += charset.decode(buff);                }                //若系统发送通知名字已经存在，则需要换个昵称                if(USER_EXIST.equals(content)) {                    name = "";                }                System.out.println(content);                sk.interestOps(SelectionKey.OP_READ);            }        }    }                public static void main(String[] args) throws IOException    {        new ChatRoomClient().init();    }}