1、服务端：

package main

import (
	"fmt"
	"net"
	"sync"
)

type ChatServer struct {
	clients    map[string]net.Conn
	clientsMux sync.Mutex
}

func NewChatServer() *ChatServer {
	return &ChatServer{
		clients: make(map[string]net.Conn),
	}
}

func (s *ChatServer) broadcast(message string, sender string) {
	s.clientsMux.Lock()
	defer s.clientsMux.Unlock()

	for clientAddr, conn := range s.clients {
		if clientAddr != sender {
			fmt.Fprintf(conn, "[%s]: %s\n", sender, message)
		}
	}
}

func (s *ChatServer) handleConnection(conn net.Conn) {
	defer conn.Close()

	clientAddr := conn.RemoteAddr().String()

	fmt.Printf("New connection from %s\n", clientAddr)

	s.clientsMux.Lock()
	s.clients[clientAddr] = conn
	s.clientsMux.Unlock()

	for {
		buffer := make([]byte, 1024)
		n, err := conn.Read(buffer)
		if err != nil {
			fmt.Printf("Error reading from %s: %v\n", clientAddr, err)
			break
		}

		message := string(buffer[:n])
		fmt.Printf("[%s]: %s\n", clientAddr, message)

		s.broadcast(message, clientAddr)
	}
}

func main() {
	server := NewChatServer()

	listener, err := net.Listen("tcp", ":8080")
	if err != nil {
		fmt.Println("Error:", err)
		return
	}
	defer listener.Close()

	fmt.Println("TCP chat server listening on :8080")

	for {
		conn, err := listener.Accept()
		if err != nil {
			fmt.Println("Error accepting connection:", err)
			continue
		}
		go server.handleConnection(conn)
	}
}

2、客户端：

package main

import (
	"bufio"
	"fmt"
	"net"
	"os"
)

func readMessages(conn net.Conn) {
	reader := bufio.NewReader(conn)
	for {
		message, err := reader.ReadString('\n')
		if err != nil {
			fmt.Println("Error reading message:", err)
			break
		}
		fmt.Print(message)
	}
}

func main() {
	conn, err := net.Dial("tcp", "127.0.0.1:8080")
	if err != nil {
		fmt.Println("Error connecting to server:", err)
		return
	}
	defer conn.Close()

	go readMessages(conn)

	for {
		scanner := bufio.NewScanner(os.Stdin)
		scanner.Scan()
		message := scanner.Text()

		_, err := conn.Write([]byte(message + "\n"))
		if err != nil {
			fmt.Println("Error sending message:", err)
			break
		}
	}
}

3、实现效果