Golang で WebSocket を使用してリアルタイムのデータ視覚化を行う方法

package main

import (
    "log"
    "net/http"

    "github.com/gorilla/websocket"
)

var clients = make(map[*websocket.Conn]bool)
var broadcast = make(chan []byte)
var upgrader = websocket.Upgrader{} // 使用默认的Upgrader

func main() {
    fs := http.FileServer(http.Dir("static"))
    http.Handle("/", fs)

    http.HandleFunc("/ws", handleConnections)

    go handleMessages()

    log.Println("Server started on :8000")
    err := http.ListenAndServe(":8000", nil)
    if err != nil {
        log.Fatal("ListenAndServe: ", err)
    }
}

func handleConnections(w http.ResponseWriter, r *http.Request) {
    // 建立WebSocket连接
    conn, err := upgrader.Upgrade(w, r, nil)
    if err != nil {
        log.Fatal(err)
    }
    // 关闭连接
    defer conn.Close()

    clients[conn] = true

    for {
        // 读取来自客户端的消息
        _, message, err := conn.ReadMessage()
        if err != nil {
            log.Printf("Error: %v", err)
            delete(clients, conn)
            break
        }
        // 将消息放入广播通道中
        broadcast <- message
    }
}

func handleMessages() {
    for {
        // 从广播通道中读取消息
        message := <-broadcast

        // 将消息发送给所有连接的客户端
        for client := range clients {
            err := client.WriteMessage(websocket.TextMessage, message)
            if err != nil {
                log.Printf("Error: %v", err)
                client.Close()
                delete(clients, client)
            }
        }
    }
}

// 在HTML文件中通过JavaScript创建WebSocket连接
const socket = new WebSocket('ws://localhost:8000/ws');

// 监听连接成功事件
socket.onopen = function (event) {
    console.log('Connected to WebSocket server');
};

// 监听收到消息事件
socket.onmessage = function (event) {
    const message = event.data;
    console.log('Received message:', message);
    // 在此处可进行实时数据可视化的操作
};

// 向服务器发送消息
function sendMessage(message) {
    socket.send(message);
}

// 在HTML文件中通过JavaScript使用D3.js库创建折线图
const margin = { top: 20, right: 20, bottom: 30, left: 50 },
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

const svg = d3.select("body").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
    .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

const x = d3.scaleLinear()
    .range([0, width]);

const y = d3.scaleLinear()
    .range([height, 0]);

const line = d3.line()
    .x(function (d) { return x(d.x); })
    .y(function (d) { return y(d.y); });

// 数据存储数组
let data = [];

socket.onmessage = function (event) {
    const message = JSON.parse(event.data);
    // 在此处进行数据处理
    data.push({ x: message.x, y: message.y });

    // 更新坐标轴范围
    x.domain(d3.extent(data, function (d) { return d.x; }));
    y.domain([0, d3.max(data, function (d) { return d.y; })]);

    // 渲染折线图
    svg.selectAll("*").remove(); // 首先清空原有内容
    svg.append("path")
        .data([data])
        .attr("class", "line")
        .attr("d", line);
}