java 网络编程基础 TCP/IP协议：

package tcpandudp.threadssockettest;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

/**
 * @ClassName Server
 * @projectName: object1
 * @author: Zhangmingda
 * @description： 群发消息
 * date: 2021/5/11.
 */
public class Server {
    private static Set<Socket> sockets = Collections.synchronizedSet(new HashSet<>());
    private static class MyRunnable implements Runnable {
        /**
         * 当前线程要处理的客户端Socket
         */
        private Socket socket;

        /**
         * @param socket 构造客户端socket
         */
        public MyRunnable(Socket socket) {
            this.socket = socket;
        }

        /**
         * 具体处理每个客户端连接请求的逻辑，封装到线程run方法中
         */
        @Override
        public void run() {
            //获取客户端发送来的数据
            String content = null;
            try (BufferedReader br = new BufferedReader(new InputStreamReader(this.socket.getInputStream()))){
                /**
                 * 每次读取一行，读取一行就广播给所有客户端，直到读尽，阻塞住，
                 */
                while ((content = br.readLine()) != null){
                    //广播给所有客端 通过socket.getOutputStream()获取输出流OutputStream
                    for (Socket s : sockets){
                        PrintStream printStream = new PrintStream(s.getOutputStream());
                        printStream.println(content);
                    }
                }
            }catch (SocketException e){
                System.out.println(socket.getInetAddress() + "已断开");;
            }
            catch (IOException e) {
                e.printStackTrace();
            }finally {
                /**
                 * 当客户端断开连接while循环跳出，关闭客户端连接，从客户端Set集合中移除客户端Socket
                 */
                sockets.remove(this.socket);
                try {
                    this.socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }finally {
                    this.socket = null;
                }
            }
        }
    }
    public static void main(String[] args) throws IOException {
        /**
         * 服务端监听端口
         */
        ServerSocket serverSocket = new ServerSocket(8888);
        /**
         * 启动后一直等待客户端连接，获取到一个客户端就保存到客户端集合中,
         * 然后启动一个新的线程处理对应客户端请求，
         * 主线程再次等待新的客户端建联
         */
        while (true){
            Socket  client = serverSocket.accept();
            sockets.add(client);
            new Thread(new MyRunnable(client)).start();
        }
    }
}

package tcpandudp.threadssockettest;

import java.io.*;
import java.net.Socket;


/**
 * @ClassName ClientTest
 * @projectName: object1
 * @author: Zhangmingda
 * @description： XXX
 * date: 2021/5/11.
 */
public class ClientTest {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket("127.0.0.1",8888);
        /**
         * 启动一个线程持续读取服务端返回的数据
         */
        new Thread(){
            @Override
            public void run() {
                String content = null;
                try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()))){
                    //阻塞式等待服务端回复的数据
                    while ((content = bufferedReader.readLine()) != null){
                        System.out.println("收到服务端返回数据：" + content);
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }.start();
        /**
         * 主线程发送数据
         */
        try (PrintStream printStream = new PrintStream(socket.getOutputStream());
             BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in))
        ){
            String line = null;
            /**
             * 如果输入的不是exit字符串，就发送输入的数据，然后一直死循环阻塞等待再次输入数据
             * 获取到了字符，内容是exit while循环false 退出
             */
            while ((line = bufferedReader.readLine()) != null && !line.equals("exit")){
                printStream.println(line);
            }
        }
    }
}