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Django Channel实时推送与聊天的示例代码

100 次  2020-07-13  分类 : python web

先来看一下最终的效果吧

开始聊天,输入消息并点击发送消息就可以开始聊天了

点击 “获取后端数据”开启实时推送

先来简单了解一下 Django Channel

Channels是一个采用Django并将其功能扩展到HTTP以外的项目,以处理WebSocket,聊天协议,IoT协议等。它基于称为ASGI的Python规范构建。

它以Django的核心为基础,并在其下面分层了一个完全异步的层,以同步模式运行Django本身,但异步处理了连接和套接字,并提供了以两种方式编写的选择,从而实现了这一点。

详情请参考官方文档:https://channels.readthedocs.io/en/latest/introduction.html

再简单说下ASGI是什么东东吧

ASGI 由 Django 团队提出,为了解决在一个网络框架里(如 Django)同时处理 HTTP、HTTP2、WebSocket 协议。为此,Django 团队开发了 Django Channels 插件,为 Django 带来了 ASGI 能力。
在 ASGI 中,将一个网络请求划分成三个处理层面,最前面的一层,interface server(协议处理服务器),负责对请求协议进行解析,并将不同的协议分发到不同的 Channel(频道);频道属于第二层,通常可以是一个队列系统。频道绑定了第三层的 Consumer(消费者)。

详情请参考官方文档:https://channels.readthedocs.io/en/latest/asgi.html

下边来说一下具体的实现步骤

一、安装channel

pip3 install channels 
pip3 install channels_redis

二、新建Django项目

1.新建项目

django-admin startproject mysite

2.新建应用

python3 manage.py startapp chat

3.编辑mysite/settings.py文件

#注册应用
INSTALLED_APPS = [
  ....
  'chat.apps.ChatConfig',
  "channels",
]

# 在文件尾部新增如下配置

#将ASGI_APPLICATION设置设置为指向该路由对象作为您的根应用程序:
ASGI_APPLICATION = 'mysite.routing.application'

#配置Redis
CHANNEL_LAYERS = {
  'default': {
    'BACKEND': 'channels_redis.core.RedisChannelLayer',
    'CONFIG': {
      "hosts": [('10.0.6.29', 6379)],
    },
  },
}

三、详细代码与配置

1. 添加索引视图的模板

chat目录中创建一个templates目录。在您刚刚创建的templates目录中,创建另一个名为的目录chat,并在其中创建一个名为的文件index.html以保存索引视图的模板

将以下代码放入chat/templates/chat/index.html

<!-- chat/templates/chat/index.html -->
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8"/>
  <title>Chat Rooms</title>
</head>
<body>
  What chat room would you like to enter?<br>
  <input id="room-name-input" type="text" size="100"><br>
  <input id="room-name-submit" type="button" value="Enter">

  <script>
    document.querySelector('#room-name-input').focus();
    document.querySelector('#room-name-input').onkeyup = function(e) {
      if (e.keyCode === 13) { // enter, return
        document.querySelector('#room-name-submit').click();
      }
    };

    document.querySelector('#room-name-submit').onclick = function(e) {
      var roomName = document.querySelector('#room-name-input').value;
      window.location.pathname = '/chat/' + roomName + '/';
    };
  </script>
</body>
</html>

2.创建聊天与消息推送模板

chat/templates/chat/room.html

<!DOCTYPE html>
<html>
<head>
  <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.5.0/jquery.min.js" type="text/javascript"></script>
  <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css" rel="external nofollow" >
  <script src="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/js/bootstrap.min.js"></script>
  <meta charset="utf-8"/>
  <title>Chat Room</title>
</head>
<body>
<textarea id="chat-log" cols="150" rows="30" class="text"></textarea><br>
<input id="chat-message-input" type="text" size="150"><br>
<input id="chat-message-submit" type="button" value="发送消息" class="input-sm">
<button id="get_data" class="btn btn-success">获取后端数据</button>
{{ room_name|json_script:"room-name" }}

<script>

  $("#get_data").click(function () {
    $.ajax({
      url: "{% url 'push' %}",
      type: "GET",
      data: {
        "room": "{{ room_name }}",
        "csrfmiddlewaretoken": "{{ csrf_token }}"
      },
    })
  });

  const roomName = JSON.parse(document.getElementById('room-name').textContent);
  const chatSocket = new WebSocket(
    'ws://' + window.location.host
    + '/ws/chat/'
    + roomName + '/'
  );
  let chatSocketa = new WebSocket(
    "ws://" + window.location.host + "/ws/push/" + roomName
  );
  chatSocket.onmessage = function (e) {
    const data = JSON.parse(e.data);
    // data 为收到后端发来的数据
    //console.log(data);
    document.querySelector('#chat-log').value += (data.message + '\n');
  };
  chatSocketa.onmessage = function (e) {
    let data = JSON.parse(e.data);
    //let message = data["message"];
    document.querySelector("#chat-log").value += (data.message + "\n");
  };


  chatSocket.onclose = function (e) {
    console.error('Chat socket closed unexpectedly');
  };
  chatSocketa.onclose = function (e) {
    console.error("Chat socket closed unexpectedly");
  };
  document.querySelector('#chat-message-input').focus();
  document.querySelector('#chat-message-input').onkeyup = function (e) {
    if (e.keyCode === 13) { // enter, return
      document.querySelector('#chat-message-submit').click();
    }
  };

  document.querySelector('#chat-message-submit').onclick = function (e) {
    const messageInputDom = document.querySelector('#chat-message-input');
    const message = messageInputDom.value;
    chatSocket.send(JSON.stringify({
      'message': message
    }));
    messageInputDom.value = '';
  };
</script>
</body>
</html>

3.创建房间的视图

将以下代码放入chat/views.py

# chat/views.py
from django.shortcuts import render
from django.http import JsonResponse
from channels.layers import get_channel_layer
from asgiref.sync import async_to_sync


def index(request):
  return render(request, "chat/index.html")


def room(request, room_name):
  return render(request, "chat/room.html", {"room_name": room_name})


def pushRedis(request):
  room = request.GET.get("room")
  print(room)

  def push(msg):
    channel_layer = get_channel_layer()
    async_to_sync(channel_layer.group_send)(
      room,
      {"type": "push.message", "message": msg, "room_name": room}
    )

  push("推送测试", )
  return JsonResponse({"1": 1})

4. 创建项目二级路由

在chat目录下创建一个名为的文件urls.py

# mysite/chat/urls.py
from django.urls import path
from . import views

urlpatterns = [
  path('', views.index, name='index'),
   path('<str:room_name>/', views.room, name='room'),
]

5. 修改根路由

# mysite/urls.py

from django.contrib import admin
from django.urls import path, include
from chat.views import pushRedis

urlpatterns = [
  path('admin/', admin.site.urls),
  path("chat/", include("chat.urls")),
  path("push", pushRedis, name="push"),
]

6.创建一个消费者

文件chat/consumers.py

当Django接受HTTP请求时,它会查询根URLconf来查找视图函数,然后调用该视图函数来处理该请求。同样,当Channels接受WebSocket连接时,它会查询根路由配置以查找使用者,然后在使用者上调用各种功能来处理来自连接的事件。

import time
import json
from channels.generic.websocket import WebsocketConsumer, AsyncWebsocketConsumer
from asgiref.sync import async_to_sync
import redis

pool = redis.ConnectionPool(
  host="10.0.6.29",
  port=6379,
  max_connections=10,
  decode_response=True,
)
conn = redis.Redis(connection_pool=pool, decode_responses=True)


class ChatConsumer(AsyncWebsocketConsumer):
  async def connect(self, ):
    self.room_name = self.scope["url_route"]["kwargs"]["room_name"]
    self.room_group_name = "chat_%s" % self.room_name

    await self.channel_layer.group_add(
      self.room_group_name,
      self.channel_name,
    )
    await self.accept()

  async def disconnect(self, close_code):
    print("close_code: ", close_code)
    await self.channel_layer.group_discard(
      self.room_group_name,
      self.channel_name
    )

  async def receive(self, text_data=None, bytes_data=None):
    text_data_json = json.loads(text_data)
    message = text_data_json["message"]
    print("receive_message:", message)
    await self.channel_layer.group_send(
      self.room_group_name,
      {
        "type": "chat_message",
        "message": message
      }
    )

  async def chat_message(self, event):
    receive_message = event["message"]
    response_message = "You message is :" + receive_message
    await self.send(text_data=json.dumps({
      "message": response_message
    }))


class PushMessage(WebsocketConsumer):

  def connect(self):
    self.room_group_name = self.scope["url_route"]["kwargs"]["room_name"]
    async_to_sync(self.channel_layer.group_add)(
      self.room_group_name,
      self.channel_name
    )
    self.accept()

  def disconnect(self, code):
    async_to_sync(self.channel_layer.group_discard)(
      self.room_group_name,
      self.channel_name
    )

  def push_message(self, event):
    """
    主动推送
    :param event:
    :return:
    """
    print(event, type(event))
    while True:
      time.sleep(2)
      msg = time.strftime("%Y-%m-%d %H:%M:%S") + "--- room_name: %s" % event["room_name"]
      self.send(text_data=json.dumps(
        {"message": msg}
      ))

7.为项目添加websocket的路由配置

在chat目录下创建一个名为的文件routing.py

# mysite/chat/routing.py

from django.urls import re_path, path
from . import consumers

websocket_urlpatterns = [
  re_path(r"ws/chat/(?P<room_name>\w+)/$", consumers.ChatConsumer),
  path("ws/push/<room_name>", consumers.PushMessage),
]

8.配置websocket根路由

与setting同级目录新建ws根路由文件 routing.py

from channels.routing import ProtocolTypeRouter, URLRouter
from channels.auth import AuthMiddlewareStack
import chat.routing

application = ProtocolTypeRouter({
  "websocket": AuthMiddlewareStack(
    URLRouter(
      chat.routing.websocket_urlpatterns
    )
  ),
})

9.最终的文件关系如下图

10.启动服务

python3 manage.py runserver 10.0.6.2:80

注意看,这和django是不一样的

还有另一种更稳健的启动方式

和setting同级新增文件 asgi.py

import os
import django
from channels.routing import get_default_application

os.environ.setdefault("DJANGO_SETTINGS_MODULE", "mysite.settings")
django.setup()
application = get_default_application()

启动方式为:

daphne -b 10.0.6.2 -p 80 mysite.asgi:application

daphne 在安装channel时已经自动安装好了

参考:

  https://channels.readthedocs.io/en/latest/tutorial/index.html

  https://blog.ernest.me/post/asgi-demonstration-realtime-blogging

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