Python Websocket 控制大屏显示

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场景描述:

在做大屏展示时,有这样一个需求:在不刷新页面的情况下,动态改变大屏展示内容,如:执行某个函数,把相关数据醒目展示,轮换数据显示顺序等等。比如有领导参观时,马上切换到领导感兴趣的页面(面向领导编程^_^)

实现思路:

1.搭建一个Websocket服务器。

2.让大屏与Websocket服务器建立长连接。(此操作存在风险,请斟酌使用)

3.再写一个控制页面,用来控制大屏展示内容(css,js)。

实现步骤:

1.搭建一个Websocket服务器,这里使用Python的websockets来搭建。话不多说,直接上代码。

import asyncio
import websockets
import time
import json
host = '0.0.0.0'
port=8765
client_list = {} #客户端列表 

# 检测客户端权限,用户名密码通过才能退出循环
async def check_permit(websocket):
    while True:
        recv_str = await websocket.recv()
        cred_dict = recv_str.split(":")
        if (cred_dict[0] == "screen" and cred_dict[1] == "123456") or (cred_dict[0] == "screencontrol" and cred_dict[1] == "123456"): 
            response_str = "{\"action\":\"login_result\",\"data\":\"登录成功\"}"
            await websocket.send(response_str)         
            return True    #关闭这个socket
        else:
            response_str ="{\"action\":\"login_result\",\"data\":\"抱歉,用户名或密码错误\"}"
            await websocket.send(response_str) #挂起,不进入下面代码

# 接收客户端消息并处理,这里只是简单把客户端发来的返回回去
async def recv_msg(websocket):
    addr=str(websocket.remote_address) 
    client_list[addr]=websocket#用addr作为客户端标识 
    print(addr, "上线了,当前在线:", len(client_list))        
    while True:
        try:
            #接收信息
            recv_text = await websocket.recv()
            print(addr+" say:"+ recv_text)   

            response=""
            #解析传入json
            o = json.loads(recv_text)
            action=o.get('action')
            data=o.get('data')

            if len(action) > 0:
                if (action=="1"):
                    response = data 
                elif (action=="2"):
                    response = data 
                else:
                    response = recv_text

            #通知其他客户端
            for key,socket in client_list.items():
                if(key!=addr):
                    await socket.send(response)


            # #返回信息
            # response_text = f"server: {recv_text}"
            # #await websocket.send(response_text)

            # #通知其他客户端
            # for key,socket in client_list.items():
            #     await socket.send(response_text)

        except Exception as error:
            print("exception:", error)
            if addr in client_list: 
                client_list.pop(addr) #从客户端列表移除
                print("当前在线:", len(client_list))   
            return True

# 服务器端主逻辑
async def main(websocket, path):
    try:
        await check_permit(websocket)
        await recv_msg(websocket)

    except Exception as error:
        print("Exception:", error)

start_server = websockets.serve(main, host, port)
asyncio.get_event_loop().run_until_complete(start_server)
asyncio.get_event_loop().run_forever() 

这里有个简单授权检查,当客户端连到Websocket服务器时,先要发送证明自己身份的消息,服务器端进行验证,通过了,才能进行后面的交互,否则直接拦截在外面。

2.大屏展示页面,此页面用于模拟大屏展示的效果。

<!DOCTYPE HTML>
<html>

<head>
    <meta charset="utf-8">
    <title>大屏演示</title>
    <script src="抱歉,仅能上传后缀为:.jpg,.png,.gif,.bmp,.rar,.zip,.ico 的文件"></script>
    <style type="text/css">
        input {
            padding: 3px;
            outline: none;
            border: 1px solid #ccc;
        }

        .log {
            padding: 10px 0;
            color: gray;
            font-size: 14px;
            line-height: 25px;
        }

        .main {
            margin: 40px auto;
            width: 80%;
        }

        .showArea {
            text-align: center;
            font-size: 48px;
            padding: 150px 0;

        }

        .title {
            border-bottom: 2px solid brown;
            padding-bottom: 10px;
        }
    </style>
</head>

<body>
    <div class="main">
        <h3 class="title">大屏演示</h3>
        <div class="showArea">
            大屏演示区域
        </div> 
        <span style="font-size: 14px;color:brown;">此处打印数据交互日志,可以根据实际情况删除或隐藏。</span>
        <div class="log"></div>
    </div>
    <script type="text/javascript">
        var ws;
        var server = "192.168.100.192";
        var port = "8765";
        $(function () {
            conn();
        })

        function onmessage(msg) {
            log(msg);

            //处理服务器返回消息
            var o = JSON.parse(msg);
            var action = o.action;
            var data = o.data;
            switch (action) {
                case "login_result":
                    break;
                case "setcss":
                    createStyleSheet(data);
                    break;
                case "runjs":
                    eval(data)
                    break;
                default:
                    break;
            }
        }

        function conn() {
            ws = new WebSocket("ws://" + server + ":" + port);
            ws.onopen = function () {
                ws.send("screen:123456");
                log("连接成功");
            };
            ws.onmessage = function (evt) {
                onmessage(evt.data);
            };
            ws.onclose = function () {
                log("连接已关闭...");
            };
        }

        function log(msg) {
            $(".log").append(getNowTime() + ":" + msg + "</br>");
        }
        function getNowTime() {
            var date = new Date();
            var year = date.getFullYear();
            var month = date.getMonth() + 1;
            var day = date.getDate();
            var hour = date.getHours();
            var minute = date.getMinutes();
            var second = date.getSeconds();
            var time = year + '-' + addZero(month) + '-' + addZero(day) + ' ' + addZero(hour) + ':' + addZero(minute) + ':' + addZero(second);
            return time;
        }
        function addZero(s) {
            return s < 10 ? ('0' + s) : s;
        }

        function createStyleSheet(css) {
            var dynamic = document.getElementById("_dynamicCss");
            if (dynamic == undefined) {
                dynamic = document.createElement('style');
                dynamic.id = "_dynamicCss";

                var head = document.head || document.getElementsByTagName('head')[0];
                head.appendChild(dynamic);
            }
            dynamic.type = 'text/css';
            dynamic.innerText = css;
        }
    </script>
    </div>
</body>

</html>

(1)页面加载完毕后,与Websocket服务器建立连接。

(2)在ws.onmessage事件处理服务器端返回的指令,此处写了3个事件类型login_result,setcss,runjs,login_result用来处理登录回调,setcss设置页面css样式,runjs用来执行js代码。

3.大屏控制页,用来控制大屏显示效果。

<!DOCTYPE HTML>
<html>

<head>
    <meta charset="utf-8">
    <title>大屏控制端</title>
    <script src="抱歉,仅能上传后缀为:.jpg,.png,.gif,.bmp,.rar,.zip,.ico 的文件"></script>
    <style type="text/css">
        * {
            font-size: 14px;
        }

        h3 {
            font-size: 18px;
        }

        .main {
            margin: 40px auto;
            width: 80%;
        }

        .main table {
            border: 1px solid #ccc;
            border-collapse: collapse;
            width: 100%;
        }

        .main .td-left {
            text-align: right;
            width: 100px;
        }

        .main table td {
            padding: 5px;
            border: 1px solid #ccc;
        }

        input,
        select,
        textarea {
            padding: 3px;
            outline: none;
            border: 1px solid #ccc;
        }

        .log {
            padding: 10px 0;
            color: gray;
            font-size: 14px;
            line-height: 25px;
        }

        input[type="button"] {
            background-color: brown;
            padding: 3px 5px;
            color: white;
            border: 0;

        }
    </style>
</head>

<body>
    <div class="main">
        <h3 style="border-bottom: 2px solid brown;padding-bottom: 10px;">大屏控制端</h3>

        <table>
            <tr>
                <td colspan="2" style="text-align: center;line-height: 32px;">
                    用此页面可以控制大屏页面的展示效果,可以追加css,可以执行js方法,实时生效。
                </td>
            </tr>
            <tr>
                <td class="td-left">服务器</td>
                <td>
                    <span class="server"></span>

                    <input type="button" value="连接" id="btnCon">
                </td>
            </tr>
            <tr>
                <td class="td-left">操作</td>
                <td>
                    <select class="action">
                        <option value="setcss">设置css样式(setcss)</option>
                        <option value="runjs">执行JS方法(runjs)</option>
                    </select>
                </td>
            </tr>
            <tr>
                <td class="td-left">内容</td>
                <td>
                    <textarea style="width: 99%;height: 200px;" class="data">body{background-color:#e3e3e3}</textarea>
                </td>
            </tr>
            <tr>
                <td class="td-left"> </td>
                <td>
                    <input type="button" value="发送消息" id="btnSend">
                    <input type="button" value="清除日志" id="btnClearLog">
                </td>
            </tr>
            <tr>
                <td class="td-left">日志</td>
                <td>
                    <div class="log"></div>
                </td>
            </tr>
        </table>

    </div>
    <script type="text/javascript">
        var ws;
        var server = "192.168.100.192";
        var port = "8765";
        $(function () {
            $(".server").text("ws://" + server + ":" + port);

            conn();
            $("#btnCon").click(function () {
                conn();
            });

            $("#btnSend").click(function () {
                if (ws.readyState == 1) {
                    var action = $(".action").val();
                    var data = $(".data").val();
                    if (action.length > 0) {
                        var o = {};
                        o["action"] = action;
                        o["data"] = data;
                        ws.send(JSON.stringify(o));
                    }
                }
            });
            $("#btnClearLog").click(function () {
                $(".log").text("");
            });

        })

        function onmessage(msg) {
            log(msg);
        }

        function conn() {
            ws = new WebSocket("ws://" + server + ":" + port);

            ws.onopen = function () {
                ws.send("screencontrol:123456");
                log("连接成功");
                $(".server").html("ws://" + server + ":" + port + "<span style='color:green'> 连接成功</span>")
            };

            ws.onmessage = function (evt) {
                onmessage(evt.data);
            };

            ws.onclose = function () {
                log("连接断开(event.code):" + event.code);
                $(".server").html("ws://" + server + ":" + port + "<span style='color:red'> 连接断开</span>")
            };
        }

        function log(msg) {
            $(".log").append(getNowTime() + ":" + msg + "</br>");
        }


        function getNowTime() {
            var date = new Date();
            var year = date.getFullYear();
            var month = date.getMonth() + 1;
            var day = date.getDate();
            var hour = date.getHours();
            var minute = date.getMinutes();
            var second = date.getSeconds();
            var time = year + '-' + addZero(month) + '-' + addZero(day) + ' ' + addZero(hour) + ':' + addZero(minute) + ':' + addZero(second);
            return time;
        }
        function addZero(s) {
            return s < 10 ? ('0' + s) : s;
        }
    </script>
    </div>
</body>

</html>

运行效果:

在大屏控制页,输入指定命令,就可以动态改版大屏展示页的效果了。

大屏连Websocket存在风险,如果Websocket服务器被黑了,就可能会显示其他内容,请谨慎使用。



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