Uvicorn（ASGI 服务器）

# 一个最原始的 ASGI 应用（不借助任何框架）
async def app(scope, receive, send):
    """scope 包含请求元信息，receive 接收数据，send 发送响应"""
    assert scope["type"] == "http"

    # 发送响应头
    await send({
        "type": "http.response.start",
        "status": 200,
        "headers": [(b"content-type", b"text/plain")],
    })
    # 发送响应体
    await send({
        "type": "http.response.body",
        "body": b"Hello, World!",
    })

# 最小安装（纯 Python 依赖）
pip install uvicorn

# 推荐：完整安装（包含 uvloop + httptools 高性能组件）
pip install "uvicorn[standard]"

# main.py
# 依赖安装：pip install "uvicorn[standard]"
import asyncio

import uvicorn

async def app(scope, receive, send):
    assert scope["type"] == "http"

    await send({
        "type": "http.response.start",
        "status": 200,
        "headers": [(b"content-type", b"text/plain; charset=utf-8")],
    })
    await send({
        "type": "http.response.body",
        "body": "Hello, Uvicorn!".encode("utf-8"),
    })

async def main():
    config = uvicorn.Config(app, host="127.0.0.1", port=8000, log_level="info")
    server = uvicorn.Server(config)

    server_task = asyncio.create_task(server.serve())
    await asyncio.sleep(1)
    server.should_exit = True
    await server_task

if __name__ == "__main__":
    asyncio.run(main())

# 方式 1：命令行启动（推荐，支持热重载）
uvicorn main:app --reload --host 127.0.0.1 --port 8000

# 方式 2：Python 直接运行（此处示例会在 1 秒后自动退出，便于演示和校验）
python main.py

INFO:     Started server process [12345]
INFO:     Waiting for application startup.
INFO:     ASGI 'lifespan' protocol appears unsupported.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)