java Socket实现多人群聊与私聊

关于Socket套接字的一些基本知识与认识可以参见上一篇或自行查阅。

ServerSocket和Socket实现群聊与私聊涉及到多线程编程，实现过程的重点是利用Socket通信的原理，即不断的在服务端和客户端创建输入输出流来相互传递、交换数据等以达到通信的目的。具体实现如下：

服务端：

import java.io.*;
import java.net.*;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;


public class TCPServer {	
	
	private ServerSocket serverSocket;
	
	/**
	* 创建线程池来管理客户端的连接线程
	* 避免系统资源过度浪费
	*/
	private ExecutorService exec;
	
	// 存放客户端之间私聊的信息
	private Map storeInfo;
	
	public TCPServer() {
		try {

			serverSocket = new ServerSocket(6789);
			storeInfo = new HashMap();
			exec = Executors.newCachedThreadPool();

		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	// 将客户端的信息以Map形式存入集合中
	private void putIn(String key,PrintWriter value) {
		synchronized(this) {
			storeInfo.put(key, value);
		}
	}
	
	// 将给定的输出流从共享集合中删除
	private synchronized void remove(String  key) {
		storeInfo.remove(key);
		System.out.println("当前在线人数为："+ storeInfo.size());
	}
	
	// 将给定的消息转发给所有客户端
	private synchronized void sendToAll(String message) {
		for(PrintWriter out: storeInfo.values()) {
			out.println(message);
		}
	}
	
	// 将给定的消息转发给私聊的客户端
	private synchronized void sendToSomeone(String name,String message) {
		PrintWriter pw = storeInfo.get(name); //将对应客户端的聊天信息取出作为私聊内容发送出去
		if(pw != null) pw.println(message);	
	}
	
	public void start() {
		try {
			while(true) {
			System.out.println("等待客户端连接... ... ");
			Socket socket = serverSocket.accept();

			// 获取客户端的ip地址
			InetAddress address = socket.getInetAddress();
			System.out.println("客户端：“" + address.getHostAddress() + "”连接成功！ ");
			/*
			* 启动一个线程，由线程来处理客户端的请求，这样可以再次监听
			* 下一个客户端的连接
			*/
			exec.execute(new ListenrClient(socket)); //通过线程池来分配线程
			}
		} catch(Exception e) {
			e.printStackTrace();
		}
	}
	
	/**
	* 该线程体用来处理给定的某一个客户端的消息，循环接收客户端发送
	* 的每一个字符串，并输出到控制台
	*/
	class ListenrClient implements Runnable {

		private Socket socket;
		private String name;
				
		public ListenrClient(Socket socket) {
			this.socket = socket;
		}
		
		// 创建内部类来获取昵称
		private String getName() throws Exception {
			try {
				//服务端的输入流读取客户端发送来的昵称输出流
				BufferedReader bReader = new BufferedReader(
					new InputStreamReader(socket.getInputStream(), "UTF-8"));
				//服务端将昵称验证结果通过自身的输出流发送给客户端
				PrintWriter ipw = new PrintWriter(
					new OutputStreamWriter(socket.getOutputStream(), "UTF-8"),true);

				//读取客户端发来的昵称
				while(true) {
					String nameString = bReader.readLine();
					if ((nameString.trim().length() == 0) || storeInfo.containsKey(nameString)) {
						ipw.println("FAIL");
					} else {
						ipw.println("OK");
						return nameString;
					}
				}
			} catch(Exception e) {
				throw e;
			}
		}
		
        @Override		
		public void run() {
			try {
				/*
				* 通过客户端的Socket获取客户端的输出流
				* 用来将消息发送给客户端
				*/
				PrintWriter pw = new PrintWriter(
					new OutputStreamWriter(socket.getOutputStream(), "UTF-8"), true);
				
				/*
				* 将客户昵称和其所说的内容存入共享集合HashMap中
				*/
				name = getName();
				putIn(name, pw);
				Thread.sleep(100);
				
				// 服务端通知所有客户端，某用户上线
				sendToAll("[系统通知] “" + name + "”已上线");
				
				/*
				* 通过客户端的Socket获取输入流
				* 读取客户端发送来的信息
				*/
				BufferedReader bReader = new BufferedReader(
					new InputStreamReader(socket.getInputStream(), "UTF-8"));
				String msgString = null;
				
				
				while((msgString = bReader.readLine()) != null) {
					// 检验是否为私聊（格式：@昵称：内容）
					if(msgString.startsWith("@")) {
						int index = msgString.indexOf(":");
						if(index >= 0) {
							//获取昵称
							String theName = msgString.substring(1, index);
							String info = msgString.substring(index+1, msgString.length());
							info =  name + "："+ info;
							//将私聊信息发送出去
							sendToSomeone(theName, info);
							continue;
						}
					}
					// 遍历所有输出流，将该客户端发送的信息转发给所有客户端
					System.out.println(name+"："+ msgString);
					sendToAll(name+"："+ msgString);
				}	
			} catch (Exception e) {
				// e.printStackTrace();
			} finally {
				remove(name);
				// 通知所有客户端，某某客户已经下线
				sendToAll("[系统通知] "+name + "已经下线了。");
				
				if(socket!=null) {
					try {
						socket.close();
					} catch(IOException e) {
						e.printStackTrace();
					}
				}	
			}
		}
	}
	
	public static void main(String[] args) {
		TCPServer server = new TCPServer();
		server.start();
	}
}

客户端：

import java.io.*;
import java.net.*;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;

public class TCPClient {
	
	static private Socket clientSocket;
	
	public TCPClient() {}

	public static void main(String[] args) throws Exception {
		Scanner scanner = new Scanner(System.in);
        String serverIP;
    
        System.out.println("请设置服务器IP：");
        serverIP = scanner.next();
        clientSocket = new Socket(serverIP, 6789);
		TCPClient client = new TCPClient();
		client.start();
	}
			
	public void start() {
		try {
			Scanner scanner = new Scanner(System.in);
			setName(scanner);
			
			// 接收服务器端发送过来的信息的线程启动
			ExecutorService exec = Executors.newCachedThreadPool();
            exec.execute(new ListenrServser());
			
			// 建立输出流，给服务端发信息
			PrintWriter pw = new PrintWriter(
				new OutputStreamWriter(clientSocket.getOutputStream(), "UTF-8"), true);
			
			while(true) {
				pw.println(scanner.nextLine());
			}
		} catch(Exception e) {
			e.printStackTrace();
		} finally {
			if (clientSocket !=null) {
				try {
					clientSocket.close();
				} catch(IOException e) {
					e.printStackTrace();
				}
			}
		}
	}

	private void setName(Scanner scan) throws Exception {
		String name;
		//创建输出流
		PrintWriter pw = new PrintWriter(
				new OutputStreamWriter(clientSocket.getOutputStream(), "UTF-8"),true);
		//创建输入流
		BufferedReader br = new BufferedReader(
				new InputStreamReader(clientSocket.getInputStream(),"UTF-8"));
		
		while(true) {	
			System.out.println("请创建您的昵称：");
			name = scan.nextLine();
			if (name.trim().equals("")) {
				System.out.println("昵称不得为空");
			} else {	
				pw.println(name);
				String pass = br.readLine();
				if (pass != null && (!pass.equals("OK"))) {
					System.out.println("昵称已经被占用，请重新输入：");
				} else {
					System.out.println("昵称“"+name+"”已设置成功，可以开始聊天了");
					break;
				}
			}
		}
	}
	
	// 循环读取服务端发送过来的信息并输出到客户端的控制台
 	class ListenrServser implements Runnable {
    
    @Override
		public void run() {
			try {
				BufferedReader br = new BufferedReader(
					new InputStreamReader(clientSocket.getInputStream(), "UTF-8"));
				String msgString;
				while((msgString = br.readLine())!= null) {
					System.out.println(msgString);
				}
			} catch(Exception e) {
				e.printStackTrace();
			}
		}
	}

}

运行结果：

开始自己的实现也不是很完整，后来也是借鉴别人比较好的思想后完善的，权当分享。