Java programming steps to implement small local area network chat application

import java.io.IOException; import java.io.PrintStream; import java.net.ServerSocket; import java.net.Socket; import java.util.Map; import java.util.Scanner; import java.util.Set; import java.util.concurrent.*; import java.util.regex.Matcher; import java.util.regex.Pattern; public class ManyThreadServer { //存储所有注册的客户端 private static Map clientMap = new ConcurrentHashMap(); //具体的处理每个客户端的请求 private static class ExcuteClient implements Runnable{ private Socket client; public ExcuteClient(Socket client) { this.client = client; } @Override public void run() { try { //获取客户端的输出流，读取客户端消息，并处理 Scanner in = new Scanner(client.getInputStream()); String strFromClient; while(true){ if(in.hasNextLine()){ strFromClient = in.nextLine(); //在Windows下默认换行是：\r\n,所以把\r要转换为空字符串 Pattern pattern = Pattern.compile("\r"); Matcher matcher = pattern.matcher(strFromClient); strFromClient = matcher.replaceAll(""); //注册流程 if(strFromClient.startsWith("useName")){ String useName = strFromClient.split("\\:")[1]; registerUser(useName,client); continue; } //群聊功能 if(strFromClient.startsWith("G")){ String msg = strFromClient.split("\\:")[1]; groupChat(msg,client); continue; } //私聊功能 if(strFromClient.startsWith("P")){ String userName = strFromClient.split("\\:")[1].split("-")[0]; String msg = strFromClient.split("\\:")[1].split("-")[1]; privateChat(userName,msg,client); continue; } //用户退出 if(strFromClient.startsWith("B")){ String userName = null; //根据Socket找到UserName for(String keyName : clientMap.keySet()){ if(clientMap.get(keyName).equals(client)){ userName = keyName; } } System.out.println("用户" + userName + "下线了。。。"); clientMap.remove(userName); System.out.println("当前共有用户" + clientMap.size() + "人"); continue; } else{ PrintStream out = new PrintStream(client.getOutputStream(),true,"UTF-8"); out.println("输入错误。。。"); } } } } catch (IOException e) { e.printStackTrace(); } } private void registerUser(String name,Socket client){ System.out.println("用户：" + name + "已上线！"); clientMap.put(name,client); System.out.println("当前在线人数：" + clientMap.size() + "人！"); //既然是用户在注册，所以这里服务器通知用户注册结果 try { PrintStream out = new PrintStream(client.getOutputStream(),true,"UTF-8"); out.println("用户注册成功！"); } catch (IOException e) { e.printStackTrace(); } } private void groupChat(String msg,Socket client){ //取出clientMap中所有的Entry对象，遍历每个用户，并且发送消息 Set> clientSet = clientMap.entrySet(); for(Map.Entry entry:clientSet){ try { Socket socket = entry.getValue(); //取得输出流，向客户端发送消息 PrintStream out = new PrintStream(socket.getOutputStream(),true,"UTF-8"); out.println("由端口号为"+ client.getPort() + "发来的群聊消息：" + msg); } catch (IOException e) { e.printStackTrace(); } } } private void privateChat(String userName,String msg,Socket client){ Socket privateSocket = clientMap.get(userName); try { PrintStream out = new PrintStream(privateSocket.getOutputStream(),true,"UTF-8"); out.println("由端口号为：" + client.getPort() + "发来的消息：" + msg); } catch (IOException e) { e.printStackTrace(); } } } public static void main(String[] args)throws Exception{ //为了提高效率，这里使用多线程进行处理 ExecutorService executorService = Executors.newFixedThreadPool(30); //实例化ServerSocket对象，并指定IP为本地主机，端口号为6666 ServerSocket serverSocket = new ServerSocket(6666); for(int i = 0; i < 30;i++){ System.out.println("等待用户连接。。。"); //等待客户端连接服务器 Socket client = serverSocket.accept(); System.out.println("有客户端连接，端口号为：" + client.getPort()); //启动线程，并处理客户端请求 executorService.submit(new ExcuteClient(client)); } //关闭线程，关闭服务器 executorService.shutdown(); serverSocket.close(); } }

import java.io.IOException; import java.io.PrintStream; import java.net.Socket; import java.util.Scanner; /** * 接收服务端发来的消息 */ class FromServer implements Runnable{ Socket client; public FromServer(Socket client){ this.client = client; } @Override public void run() { try { Scanner in = new Scanner(client.getInputStream()); while (true) { if (in.hasNextLine()) { System.out.println("服务器：" + in.nextLine()); } //判断客户端是否退出，如果推出，跳出循环，并关闭流 if (client.isClosed()) { System.out.println("客户端关闭。。。"); break; } } in.close(); } catch (IOException e) { e.printStackTrace(); } } } /** * 向服务端发出消息 */ class ToServer implements Runnable{ Socket client; public ToServer(Socket client){ this.client = client; } @Override public void run() { try { Scanner scanner = new Scanner(System.in); PrintStream out = new PrintStream(client.getOutputStream(),true,"UTF-8"); while (true) { System.out.println("请输入信息："); String strToserver; if(scanner.hasNextLine()){ strToserver = scanner.nextLine().trim(); out.println(strToserver); //客户端退出标志：B if(strToserver.startsWith("B")){ System.out.println("客户端退出。。。"); scanner.close(); out.close(); client.close(); break; } } } } catch (IOException e) { e.printStackTrace(); } } } public class ManyThreadClient { public static void main(String[] args){ try { //实例化Socket对象，与服务器建立连接 Socket client = new Socket("127.0.0.1",6666); //为了发送消息和接收消息可以同时进行，使用多线程进行处理 Thread thread1 = new Thread(new FromServer(client)); Thread thread2 = new Thread(new ToServer(client)); thread1.start(); thread2.start(); } catch (IOException e) { e.printStackTrace(); } } }