websocket简单使用

待我称王封你为后i 2022-03-02 18:48 304阅读 0赞

## 简单实现 ##

参考:[https://websockets.readthedoc...][https_websockets.readthedoc...]  
PS:此文章只限于python版本大于3.6

1.  前期准备

> pip install websocket

server端

import asyncio
    import websockets
    
    async def hello(websocket, path):
        print(path)                    #这里会在client开始连接时就调用
        name = await websocket.recv()       #这里会挺住,等待client发送消息
        print(f"< {name}")
    
        greeting = f"Hello {name}!"
    
        await websocket.send(greeting)
        print(f"> {greeting}")
    
    start_server = websockets.serve(hello, 'localhost', 8765)
    
    asyncio.get_event_loop().run_until_complete(start_server)   #先执行这里
    asyncio.get_event_loop().run_forever()                      #在这里停住,等待

client

import asyncio
    import websockets
    
    async def hello():
        async with websockets.connect(
                'ws://localhost:8765') as websocket:
            name = input("What's your name? ")
    
            await websocket.send(name)
            print(f"> {name}")
    
            greeting = await websocket.recv()
            print(f"< {greeting}")
    
    asyncio.get_event_loop().run_until_complete(hello())

## 二:加密实现 ##

server

import asyncio
    import pathlib
    import ssl
    import websockets
    
    async def hello(websocket, path):
        name = await websocket.recv()
        print(f"< {name}")
    
        greeting = f"Hello {name}!"
    
        await websocket.send(greeting)
        print(f"> {greeting}")
    
    ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
    ssl_context.load_cert_chain(
        pathlib.Path(__file__).with_name('localhost.pem'))  #这里应该是要填写加密的文件,此处没有深入研究
    
    start_server = websockets.serve(
        hello, 'localhost', 8765, ssl=ssl_context)
    
    asyncio.get_event_loop().run_until_complete(start_server)
    asyncio.get_event_loop().run_forever()

client

import asyncio
    import pathlib
    import ssl
    import websockets
    
    ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
    ssl_context.load_verify_locations(
        pathlib.Path(__file__).with_name('localhost.pem'))
    
    async def hello():
        async with websockets.connect(
                'wss://localhost:8765', ssl=ssl_context) as websocket:
            name = input("What's your name? ")
    
            await websocket.send(name)
            print(f"> {name}")
    
            greeting = await websocket.recv()
            print(f"< {greeting}")
    
    asyncio.get_event_loop().run_until_complete(hello())

## 三:服务器和浏览器的实现 ##

server

import asyncio
    import datetime
    import random
    import websockets
    
    async def time(websocket, path):
        while True:
            now = datetime.datetime.utcnow().isoformat() + 'Z'
            await websocket.send(now)
            await asyncio.sleep(random.random() * 3)
    
    start_server = websockets.serve(time, '127.0.0.1', 5678)
    
    asyncio.get_event_loop().run_until_complete(start_server)
    asyncio.get_event_loop().run_forever()

browser

<!DOCTYPE html>
    <html>
        <head>
            <title>WebSocket demo</title>
        </head>
        <body>
            <script>
                var ws = new WebSocket("ws://127.0.0.1:5678/"),
                    messages = document.createElement('ul');
                ws.onmessage = function (event) {
                    var messages = document.getElementsByTagName('ul')[0],
                        message = document.createElement('li'),
                        content = document.createTextNode(event.data);
                    message.appendChild(content);
                    messages.appendChild(message);
                };
                document.body.appendChild(messages);
            </script>
        </body>
    </html>

> PS:此处先执行server代码,然后再打开浏览器就可以看到过程

## 同步例子 ##

server

import asyncio
    import json
    import logging
    import websockets
    
    logging.basicConfig()
    
    STATE = {'value': 0}
    
    USERS = set()
    
    def state_event():
        return json.dumps({'type': 'state', **STATE})
    
    def users_event():
        return json.dumps({'type': 'users', 'count': len(USERS)})
    
    async def notify_state():
        if USERS:       # asyncio.wait doesn't accept an empty list
            message = state_event()
            await asyncio.wait([user.send(message) for user in USERS])
    
    async def notify_users():
        if USERS:       # asyncio.wait doesn't accept an empty list
            message = users_event()
            await asyncio.wait([user.send(message) for user in USERS])
    
    async def register(websocket):
        USERS.add(websocket)
        await notify_users()
    
    async def unregister(websocket):
        USERS.remove(websocket)
        await notify_users()
    
    async def counter(websocket, path):
        # register(websocket) sends user_event() to websocket
        await register(websocket)
        try:
            await websocket.send(state_event())
            async for message in websocket:
                data = json.loads(message)
                if data['action'] == 'minus':
                    STATE['value'] -= 1
                    await notify_state()
                elif data['action'] == 'plus':
                    STATE['value'] += 1
                    await notify_state()
                else:
                    logging.error(
                        "unsupported event: {}", data)
        finally:
            await unregister(websocket)
    
    asyncio.get_event_loop().run_until_complete(
        websockets.serve(counter, 'localhost', 6789))
    asyncio.get_event_loop().run_forever()

client

<!DOCTYPE html>
    <html>
        <head>
            <title>WebSocket demo</title>
            <style type="text/css">
                body {
                    font-family: "Courier New", sans-serif;
                    text-align: center;
                }
                .buttons {
                    font-size: 4em;
                    display: flex;
                    justify-content: center;
                }
                .button, .value {
                    line-height: 1;
                    padding: 2rem;
                    margin: 2rem;
                    border: medium solid;
                    min-height: 1em;
                    min-width: 1em;
                }
                .button {
                    cursor: pointer;
                    user-select: none;
                }
                .minus {
                    color: red;
                }
                .plus {
                    color: green;
                }
                .value {
                    min-width: 2em;
                }
                .state {
                    font-size: 2em;
                }
            </style>
        </head>
        <body>
            <div class="buttons">
                <div class="minus button">-</div>
                <div class="value">?</div>
                <div class="plus button">+</div>
            </div>
            <div class="state">
                <span class="users">?</span> online
            </div>
            <script>
                var minus = document.querySelector('.minus'),
                    plus = document.querySelector('.plus'),
                    value = document.querySelector('.value'),
                    users = document.querySelector('.users'),
                    websocket = new WebSocket("ws://127.0.0.1:6789/");
                minus.onclick = function (event) {
                    websocket.send(JSON.stringify({action: 'minus'}));
                }
                plus.onclick = function (event) {
                    websocket.send(JSON.stringify({action: 'plus'}));
                }
                websocket.onmessage = function (event) {
                    data = JSON.parse(event.data);
                    switch (data.type) {
                        case 'state':
                            value.textContent = data.value;
                            break;
                        case 'users':
                            users.textContent = (
                                data.count.toString() + " user" +
                                (data.count == 1 ? "" : "s"));
                            break;
                        default:
                            console.error(
                                "unsupported event", data);
                    }
                };
            </script>
        </body>
    </html>

> websocket提供一个查看当前状态的接口  
> python -m websockets wss://echo.websocket.org/

如果Python版本是3.5以下

server

import asyncio
    import websockets
    
    @asyncio.coroutine
    def hello(websocket, path):
        name = yield from websocket.recv()
        print("< {}".format(name))
    
        greeting = "Hello {}!".format(name)
    
        yield from websocket.send(greeting)
        print("> {}".format(greeting))
    
    start_server = websockets.serve(hello, 'localhost', 8765)
    
    asyncio.get_event_loop().run_until_complete(start_server)
    asyncio.get_event_loop().run_forever()

client

import asyncio
    import websockets
    
    @asyncio.coroutine
    def hello():
        websocket = yield from websockets.connect(
            'ws://localhost:8765/')
    
        try:
            name = input("What's your name? ")
    
            yield from websocket.send(name)
            print("> {}".format(name))
    
            greeting = yield from websocket.recv()
            print("< {}".format(greeting))
    
        finally:
            yield from websocket.close()
    
    asyncio.get_event_loop().run_until_complete(hello())

[https_websockets.readthedoc...]: https://websockets.readthedocs.io/en/stable/intro.html#common-patterns