Tornado简单使用

1 介绍

Tornado 是一个基于Python的Web服务框架和异步网络库，它最初由 FriendFeed 开发，后来被 Facebook 收购并开源，通过利用非阻塞网络 I/O, Tornado 可以承载成千上万的活动连接，完美的实现了长连接、WebSockets, 和其他对于每一位用户来说需要长连接的程序.

# 官网地址
https://www.tornadoweb.org/en/stable/

# 多进程文档
https://www.tornadoweb.org/en/stable/httpserver.html#

# 安装Tornado
pip install tornado==6.3.3 -i https://pypi.tuna.tsinghua.edu.cn/simple

# 原生Websocket标准
https://websockets.spec.whatwg.org/

2 简单使用

helloword.py

python 复制代码

import asyncio
import tornado

class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.write("Hello, world")

def make_app():
    return tornado.web.Application([
        (r"/", MainHandler),
    ])

async def main():
    app = make_app()
    app.listen(8888)
    await asyncio.Event().wait()

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

请求地址

# 地址
http://127.0.0.1:8888/

# 返回值
Hello, world

3 简单Web工程

3.1 Python代码

工程目录

base_web_handler.py

import logging

import tornado
from tornado.escape import json_decode, to_unicode


class BaseHandler(tornado.web.RequestHandler):

    # def set_default_headers(self):
    # 设置参数
    # pass

    def get_json_argument(self, name, default=None):
        # 解析参数
        args = {}
        try:
            args = json_decode(self.request.body)
        except Exception as e:
            logging.info("json is error")
            pass
        # 编码数据
        name = to_unicode(name)

        # 解析参数
        if name in args:
            return args[name]
        elif default is not None:
            return default
        else:
            # 通知参数异常
            raise tornado.web.MissingArgumentError(name)

message_handler.py

import tornado.websocket


class MessageWebSocket(tornado.websocket.WebSocketHandler):

    # 验证连接
    def check_origin(self, origin):
        # 用于验证跨域（cross-origin requests）
        print(origin)

        # 返回true才能连接，返回false不能连接
        return True

    def open(self):
        # 建立连接
        print("WebSocket opened")

    def on_message(self, message):
        print("Received message:", message)

        self.write_message("Received message:" + "zhonguodoe")
        pass

    def on_close(self):
        print("WebSocket closed")

form_handler.py

from config.base_web_handler import BaseHandler


class FormHandler(BaseHandler):

    def get(self):
        # 获取表单参数
        print(self.get_arguments("name"))
        print(self.get_argument("name"))

        print(self.get_body_arguments("name"))
        print(self.get_body_argument("name"))

        self.write("Hello, world")

json_handler.py

from config.base_web_handler import BaseHandler


class JsonHandler(BaseHandler):
    # post方法
    def post(self):
        # 获取body参数
        # 注意：Tornado本身没有将body解析json的方法，下面方法是自己封装的BaseHandler中构建的
        print(self.get_json_argument("data"))

        self.write("Hello, world")

sse_handler.py

import asyncio

from tornado import gen

from config.base_web_handler import BaseHandler


class SseHandler(BaseHandler):
    def set_default_headers(self):
        # 设置为事件驱动模式
        self.set_header('Content-Type', "text/event-stream")
        # 不使用缓存
        self.set_header('Content-Control', "no-cache")
        # 保持长连接
        self.set_header('Connection', "keep-alive")
        # 允许跨域
        self.set_header('Access-Control-Allow-Origin', "*")

    # 使用协程调度实现并发
    @gen.coroutine
    def get(self):
        # 使用生成器来发送数据流
        for i in range(3):
            self.write(self.build_message("test" + str(i)))
            yield asyncio.sleep(1)
            print("test1" + str(i))

            # 发送数据并在这里暂停，直到下一次生成器被迭代
            self.flush()

        # 数据流发送完毕后，调用finish结束请求
        self.finish()


    def build_message(sekf, message: str, event="message"):
        """
        构建消息
        :param message: 数据消息
        :param event: 事件，默认事件是"message"，可以根据自己的需求定制事件，对应前端的eventSource.addEventListener('message',()=>{}, false)中的message。
        :return:
        """
        head = "event:" + event + "\n" + "data:"
        tail = "\n\n"
        return head + message + tail

main.py

import asyncio

import tornado
from tornado.httpserver import HTTPServer
from tornado.netutil import bind_sockets

from route import make_app


# 单进程
async def main():
    app = make_app()
    app.listen(8881)
    await asyncio.Event().wait()

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



"""

# 多进程，只有在多颗CPU上才能运行，不支持Windows
def main():
    sockets = bind_sockets(8888)
    tornado.process.fork_processes(0)

    async def post_fork_main():
        # 创建APP
        app = make_app()

        # 创建服务
        server = HTTPServer(app)
        server.add_sockets(sockets)
        await asyncio.Event().wait()

    asyncio.run(post_fork_main())


if __name__ == '__main__':
    main()
    
"""

route.py

import tornado

from socket_handler.message_handler import MessageWebSocket
from web_handler.form_handler import FormHandler
from web_handler.json_handler import JsonHandler
from web_handler.sse_handler import SseHandler


def make_app():
    return tornado.web.Application([
        # 验证基础表单
        (r"/form", FormHandler),
        (r"/json", JsonHandler),

        (r"/sse", SseHandler),

        # Websocket请求
        (r"/msg", MessageWebSocket),

    ])

3.2 前端代码

Vue3的SSE代码

<script setup lang="ts">
import { onBeforeUnmount} from 'vue'

defineProps<{ msg: string }>()


// 定义EventSource
let eventSource: any = null


// 建立连接
function createSseConnect(dataId: string) {
  if (window.EventSource) {
    // 创建连接
    eventSource = new EventSource('http://127.0.0.1:8881/sse');

    console.log("test");

    // 接收消息
    eventSource.onmessage = (event: MessageEvent) => {
      console.log(event)
      console.log("onmessage:" + dataId + ": " + event.data)
    };

    // // 也可以使用addEventListener实现自定义事件和默认message事件
    // eventSource.addEventListener('message', (event: MessageEvent)=> {
    //     console.log("message" + dataId + ": " + event.data);
    // }, false);


    // 打开连接
    eventSource.onopen = (event: Event) => {
      console.log("onopen:" + dataId + ": " + event)
    };

    // 连接出错时
    eventSource.onerror = (event: Event) => {
      console.log(event)
      console.log("onerror :" + dataId + ": " + event)
      eventSource.close();
    };

  } else {
    console.log("浏览器不支持SSE")
  }
}

// 组件销毁
onBeforeUnmount(() => {
  // 关闭EventSource
  if(eventSource != null){
    eventSource.close()
  }
})

</script>

<template>
  <h1>{{ msg }}</h1>

  <input type="button" value="发送消息" v-on:click="createSseConnect('1234')" />

</template>

<style scoped>
.read-the-docs {
  color: #888;
}
</style>

Html5的WebSocket

<!DOCTYPE HTML>
<html>

<head>
    <meta charset="utf-8">
    <script type="text/javascript">
        function WebSocketTest() {
            if ("WebSocket" in window) {
                // 构建WebSocket
                var ws = new WebSocket("ws://localhost:8881/msg");

                ws.onopen = function () {
                    // Web Socket 已连接上，使用 send() 方法发送数据
                    ws.send("发送数据");
                    alert("数据发送中...");
                };

                ws.onmessage = function (evt) {
                    var received_msg = evt.data;
                    console.log(received_msg)
                    //   alert("数据已接收...");
                };

                ws.onclose = function () {
                    // 关闭 websocket
                    alert("连接已关闭...");
                };
            }else {
                // 浏览器不支持 WebSocket
                alert("您的浏览器不支持 WebSocket!");
            }
        }
    </script>

</head>

<body>

    <div id="sse">
        <a href="javascript:WebSocketTest()">运行 WebSocket</a>
    </div>

</body>

</html>

3.3 请求地址

# 表单请求
http://127.0.0.1:8888/form

# json请求
http://127.0.0.1:8888/json

# WebSocket请求
ws://127.0.0.1:8881/msg

# SSE请求
http://127.0.0.1:8881/sse