记录两段基础代码，分别来自官网与互联网。

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from fastapi import FastAPI, WebSocket
from fastapi.responses import HTMLResponse

app = FastAPI()

html = """
<!DOCTYPE html>
<html>
    <head>
        <title>Chat</title>
    </head>
    <body>
        <h1>WebSocket Chat</h1>
        <form action="" onsubmit="sendMessage(event)">
            <input type="text" id="messageText" autocomplete="off"/>
            <button>Send</button>
        </form>
        <ul id='messages'>
        </ul>
        <script>
            var ws = new WebSocket("ws://localhost:8000/ws");
            ws.onmessage = function(event) {
                var messages = document.getElementById('messages')
                var message = document.createElement('li')
                var content = document.createTextNode(event.data)
                message.appendChild(content)
                messages.appendChild(message)
            };
            function sendMessage(event) {
                var input = document.getElementById("messageText")
                ws.send(input.value)
                input.value = ''
                event.preventDefault()
            }
        </script>
    </body>
</html>
"""


@app.get("/")
async def get():
    return HTMLResponse(html)


@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    while True:
        data = await websocket.receive_text()
        await websocket.send_text(f"Message text was: {data}")
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from typing import List

from fastapi import FastAPI, WebSocket, WebSocketDisconnect

app = FastAPI()


class ConnectionManager:
    def __init__(self):
        # 存放激活的ws连接对象
        self.active_connections: List[WebSocket] = []

    async def connect(self, ws: WebSocket):
        # 等待连接
        await ws.accept()
        # 存储ws连接对象
        self.active_connections.append(ws)

    def disconnect(self, ws: WebSocket):
        # 关闭时 移除ws对象
        self.active_connections.remove(ws)

    @staticmethod
    async def send_personal_message(message: str, ws: WebSocket):
        # 发送个人消息
        await ws.send_text(message)

    async def broadcast(self, message: str):
        # 广播消息
        for connection in self.active_connections:
            await connection.send_text(message)


manager = ConnectionManager()


@app.websocket("/ws/{user}")
async def websocket_endpoint(websocket: WebSocket, user: str):

    await manager.connect(websocket)

    await manager.broadcast(f"用户{user}进入聊天室")

    try:
        while True:
            data = await websocket.receive_text()
            await manager.send_personal_message(f"你说了: {data}", websocket)
            await manager.broadcast(f"用户:{user} 说: {data}")

    except WebSocketDisconnect:
        manager.disconnect(websocket)
        await manager.broadcast(f"用户-{user}-离开")

if __name__ == "__main__":
    import uvicorn
    # 官方推荐是用命令后启动 uvicorn main:app --host=127.0.0.1 --port=8010 --reload
    uvicorn.run(app='main:app', host="127.0.0.1", port=8010, reload=True, debug=True)