Java NIO示例：多人網絡聊天室

一個多客戶端聊天室，支持多客戶端聊天，有如下功能：

• 功能1： 客戶端通過Java NIO連接到服務端，支持多客戶端的連接
• 功能2：客戶端初次連接時，服務端提示輸入昵稱，如果昵稱已經有人使用，提示重新輸入，如果昵稱唯一，則登錄成功，之后發送消息都需要按照規定格式帶着昵稱發送消息
• 功能3：客戶端登錄后，發送已經設置好的歡迎信息和在線人數給客戶端，並且通知其他客戶端該客戶端上線
• 功能4：服務器收到已登錄客戶端輸入內容，轉發至其他登錄客戶端。
• 功能5 TODO：客戶端下線檢測  方案是：客戶端在線的時候發送心跳，服務端用TimeCacheMap自動刪除過期對象，同時通知線上用戶刪掉的用戶下線。

下面演示下效果，代碼見附錄！

 

啟動服務器，監聽某個端口

服務器console

Server is listening now...

 

啟動一個客戶端，連接服務器

服務器console

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

客戶端console

Please input your name.

 

客戶端輸入一個昵稱

服務端console

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

客戶端console

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

 

再啟動另外一個客戶端，並輸入昵稱

服務端console

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

客戶端byr1 console

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

客戶端byr2 console

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

 

客戶端byr1發送一個消息，客戶byr2回一條消息

服務端console

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

客戶端byr1 console

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

客戶端byr2 console

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

 

附錄：server和client代碼

server代碼

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;
/**
 * 網絡多客戶端聊天室
 * 功能1： 客戶端通過Java NIO連接到服務端，支持多客戶端的連接
 * 功能2：客戶端初次連接時，服務端提示輸入昵稱，如果昵稱已經有人使用，提示重新輸入，如果昵稱唯一，則登錄成功，之后發送消息都需要按照規定格式帶着昵稱發送消息
 * 功能3：客戶端登錄后，發送已經設置好的歡迎信息和在線人數給客戶端，並且通知其他客戶端該客戶端上線
 * 功能4：服務器收到已登錄客戶端輸入內容，轉發至其他登錄客戶端。
 * 
 * TODO 客戶端下線檢測
 */
public class ChatRoomServer {

    private Selector selector = null;
    static final int port = 9999;
    private Charset charset = Charset.forName("UTF-8");
    //用來記錄在線人數，以及昵稱
    private static HashSet<String> users = new HashSet<String>();
    
    private static String USER_EXIST = "system message: user exist, please change a name";
    //相當於自定義協議格式，與客戶端協商好
    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);
        //注冊到選擇器上，設置為監聽狀態
        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();  //可以通過這個方法，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);
            //注冊選擇器，並設置為讀取模式，收到一個連接請求，然后起一個SocketChannel，並注冊到selector上，之后這個連接的數據，就由這個SocketChannel處理
            sc.register(selector, SelectionKey.OP_READ);
            
            //將此對應的channel設置為准備接受其他客戶端請求
            sk.interestOps(SelectionKey.OP_ACCEPT);
            System.out.println("Server is listening from client :" + sc.getRemoteAddress());
            sc.write(charset.encode("Please input your name."));
        }
        //處理來自客戶端的數據讀取請求
        if(sk.isReadable())
        {
            //返回該SelectionKey對應的 Channel，其中有數據需要讀取
            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);
                //將此對應的channel設置為准備下一次接受數據
                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);
                //注冊用戶
                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);
                    }
                } 
                //注冊完了，發送消息
                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)) {
                        //不回發給發送此內容的客戶端
                        BroadCast(selector, sc, message);
                    }
                }
            }
            
        }
    }
    
    //TODO 要是能檢測下線，就不用這么統計了
    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 {
        //廣播數據到所有的SocketChannel中
        for(SelectionKey key : selector.keys())
        {
            Channel targetchannel = key.channel();
            //如果except不為空，不回發給發送此內容的客戶端
            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代碼

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();
        //連接遠程主機的IP和端口
        sc = SocketChannel.open(new InetSocketAddress("127.0.0.1",port));
        sc.configureBlocking(false);
        sc.register(selector, SelectionKey.OP_READ);
        //開辟一個新線程來讀取從服務器端的數據
        new Thread(new ClientThread()).start();
        //在主線程中 從鍵盤讀取數據輸入到服務器端
        Scanner scan = new Scanner(System.in);
        while(scan.hasNextLine())
        {
            String line = scan.nextLine();
            if("".equals(line)) continue; //不允許發空消息
            if("".equals(name)) {
                name = line;
                line = name+USER_CONTENT_SPILIT;
            } else {
                line = name+USER_CONTENT_SPILIT+line;
            }
            sc.write(charset.encode(line));//sc既能寫也能讀，這邊是寫
        }
        
    }
    private class ClientThread implements Runnable
    {
        public void run()
        {
            try
            {
                while(true) {
                    int readyChannels = selector.select();
                    if(readyChannels == 0) continue; 
                    Set selectedKeys = selector.selectedKeys();  //可以通過這個方法，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 讀取 Channel中的數據，這個和全局變量sc是一樣的，因為只注冊了一個SocketChannel
                //sc既能寫也能讀，這邊是讀
                SocketChannel sc = (SocketChannel)sk.channel();
                
                ByteBuffer buff = ByteBuffer.allocate(1024);
                String content = "";
                while(sc.read(buff) > 0)
                {
                    buff.flip();
                    content += charset.decode(buff);
                }
                //若系統發送通知名字已經存在，則需要換個昵稱
                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();
    }
}