package com.fancy;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.io.PrintWriter;

import java.net.ServerSocket;

import java.net.Socket;

import java.util.HashMap;

import java.util.Map;

public class Server {

    private int port;

    private ServerSocket server;

    private Map<String,PrintWriter> clients = new HashMap();

    public Server() throws IOException {

        port = 10025;

        server = new ServerSocket(port);

        System.out.println("成功创建服务器端!");

        startReceive();

    }

    public void startReceive() throws IOException{

        while(true){

            Socket socket = server.accept();

            //InetAddress address = socket.getInetAddress();

            ClientHandler handler = new ClientHandler(socket);

            new Thread(handler).start();

        }

    }

    public void sendMsg(String from,String str) throws IOException {

        for(String k:clients.keySet()){

            if(k.equals(from)){

                continue;

            }

            PrintWriter pw = clients.get(k);

            pw.println(str);

            pw.flush();

        }

    }

    class ClientHandler implements Runnable{

        private String nickname;

        private Socket socket;

        private PrintWriter pw;

        public ClientHandler(Socket socket){

            this.socket = socket;

        }

        @Override

        public void run() {

            BufferedReader br = null;

            try {

                InputStream in = socket.getInputStream();

                br = new BufferedReader(new InputStreamReader(in));

                OutputStream out = socket.getOutputStream();

                pw = new PrintWriter(out,true);

                String name = br.readLine();

                this.nickname = name;

                if(!clients.containsKey(name)){

                    clients.put(name, pw);

                    pw.println("欢迎新朋友:"+name+",当前在线人数："+clients.size());

                }

                String str;

                while((str = br.readLine())!=null){

                    if("exit".equalsIgnoreCase(str.trim())){

                        clients.remove(this.nickname);

                        this.socket.close();

                        sendMsg("all", this.nickname+"下线了，当前在线人数："+clients.size());

                    }else{

                        sendMsg(name,name+"："+str);

                    }

                }

            } catch (Exception e) {

                e.printStackTrace();

            } finally{

                try {

                    br.close();

                } catch (IOException e) {

                }

            }

        }

    }

    public static void main(String[] args) {

        try {

            Server s = new Server();

        } catch (IOException e) {

            e.printStackTrace();

        }

    }

}

package com.fancy;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.io.PrintWriter;

import java.net.Socket;

import java.net.UnknownHostException;

import java.util.Scanner;

public class Client {

    private Socket socket;

    private boolean online = true;

    public Client() throws UnknownHostException, IOException {

        socket = new Socket("127.0.0.1", 10025);

        OutputStream out = socket.getOutputStream();

        PrintWriter pw = new PrintWriter(out, true);

        Scanner scan = new Scanner(System.in);

        String word;

        ServerHandler hander = new ServerHandler();

        new Thread(hander).start();

        System.out.println("请输入您的昵称:");

        word = scan.nextLine();

        pw.println(word);

        pw.flush();

        while((word=scan.nextLine())!=null){

            pw.println(word);

            pw.flush();

            if("exit".equalsIgnoreCase(word)){

                online = false;

                break;

            }

        }

    }

    class ServerHandler implements Runnable{

        @Override

        public void run() {

            while(online){

                InputStream in;

                try {

                    in = socket.getInputStream();

                    BufferedReader br = new BufferedReader(new InputStreamReader(in));

                    String back = br.readLine();

                    System.out.println(back);

                } catch (IOException e) {

                    e.printStackTrace();

                }

            }

        }

    }

    public static void main(String[] args) {

        try {

            Client c = new Client();

            System.out.println("started!");

        } catch (UnknownHostException e) {

            e.printStackTrace();

        } catch (IOException e) {

            e.printStackTrace();

        }

    }

}