需求：

实现一个WebSocket服务器与客户端，允许客户端与服务器进行双向实时通信。

代码：

WebSocket服务器代码：

package main

import (
	"fmt"
	"log"
	"net/http"
	"github.com/gorilla/websocket"
)

// WebSocket upgrader to upgrade HTTP connections to WebSocket connections
var upgrader = websocket.Upgrader{
	CheckOrigin: func(r *http.Request) bool { return true },
}

func handleConnection(w http.ResponseWriter, r *http.Request) {
	// Upgrade HTTP request to WebSocket
	conn, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Println(err)
		return
	}
	defer conn.Close()

	// Read and send messages
	for {
		messageType, p, err := conn.ReadMessage()
		if err != nil {
			log.Println(err)
			return
		}
		fmt.Printf("Received: %s\n", string(p))

		// Echo the message back to the client
		err = conn.WriteMessage(messageType, p)
		if err != nil {
			log.Println(err)
			return
		}
	}
}

func main() {
	http.HandleFunc("/ws", handleConnection)

	// Start the WebSocket server
	fmt.Println("WebSocket server started at ws://localhost:8080/ws")
	log.Fatal(http.ListenAndServe(":8080", nil))
}

WebSocket客户端代码：

package main

import (
	"fmt"
	"log"
	"github.com/gorilla/websocket"
)

func main() {
	// Connect to the WebSocket server
	conn, _, err := websocket.DefaultDialer.Dial("ws://localhost:8080/ws", nil)
	if err != nil {
		log.Fatal(err)
	}
	defer conn.Close()

	// Send a message to the server
	message := []byte("Hello, WebSocket Server!")
	err = conn.WriteMessage(websocket.TextMessage, message)
	if err != nil {
		log.Fatal(err)
	}

	// Receive the echo message from the server
	_, response, err := conn.ReadMessage()
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("Received from server: %s\n", response)
}

解释：

• WebSocket服务器：使用gorilla/websocket库来处理WebSocket连接，接收客户端消息并将其回显。
• WebSocket客户端：连接到服务器并发送消息，接收服务器的回应并打印。

扩展：

• 你可以创建一个聊天室应用，允许多个客户端通过WebSocket互相通信。
• 使用channels来处理多个客户端的并发消息。