WebSocket 是什么？
WebSocket 是一种网络通信协议。RFC6455 定义了它的通信标准。
WebSocket 是 HTML5 开始提供的一种在单个 TCP 连接上进行全双工通讯的协议。
为什么需要 WebSocket ？
了解计算机网络协议的人，应该都知道：HTTP 协议是一种无状态的、无连接的、单向的应用层协议。它采用了请求/响应模型。通信请求只能由客户端发起，服务端对请求做出应答处理。
这种通信模型有一个弊端：HTTP 协议无法实现服务器主动向客户端发起消息。
这种单向请求的特点，注定了如果服务器有连续的状态变化，客户端要获知就非常麻烦。大多数 Web 应用程序将通过频繁的异步JavaScript和XML（AJAX）请求实现长轮询。轮询的效率低，非常浪费资源（因为必须不停连接，或者 HTTP 连接始终打开）。
WebSocket 如何工作？
Web浏览器和服务器都必须实现 WebSockets 协议来建立和维护连接。由于 WebSockets 连接长期存在，与典型的HTTP连接不同，对服务器有重要的影响。
基于多线程或多进程的服务器无法适用于 WebSockets，因为它旨在打开连接，尽可能快地处理请求，然后关闭连接。任何实际的 WebSockets 服务器端实现都需要一个异步服务器。
-服务端（socket服务器）
1.服务器开启socket，监听ip和端口
3.允许连接
* 5.服务端收到特殊值【特殊值加密sha1,migic string="258EAFA5-E914-47DA-95CA-C5AB0DC85B11"】
* 6.加密后的值发送给客户端
-客户端（浏览器）
2.客户端发起连接请求（ip和端口）
* 4.客户端生成一个随机字符串xxx,【特殊值加密sha1,migic string="258EAFA5-E914-47DA-95CA-C5AB0DC85B11"】，向服务端发送一段特殊值
* 7.客户端收到加密的值
***收发数据***
""" 1.位运算，右移动 10010001 右4 00001001 左4 100100010000 2.异或运算 1，1：1 0，1 ：0 0，0 ：0 查看某个数的后四位 10001010 00001111 00001010 info = b'x81x8bxc9x11x81bxa1txedx0exa61xf6 xbb}xe5' opcode = info[0] & 15 获取第一个字节的后四位 fin = info[0] >> 7 payload_len = info[1] & 127 if payload_len<126: 头部占2个字节 elif payload_len == 126: 头部占4个字节 else: 头部占10个字节 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-------+-+-------------+-------------------------------+ |F|R|R|R| opcode|M| Payload len | Extended payload length | |I|S|S|S| (4) |A| (7) | (16/64) | |N|V|V|V| |S| | (if payload len==126/127) | | |1|2|3| |K| | | +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - + | Extended payload length continued, if payload len == 127 | + - - - - - - - - - - - - - - - +-------------------------------+ | |Masking-key, if MASK set to 1 | +-------------------------------+-------------------------------+ | Masking-key (continued) | Payload Data | +-------------------------------- - - - - - - - - - - - - - - - + : Payload Data continued ... : + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - + | Payload Data continued ... | +------------------------------------------------------------
WebSocket 客户端
在客户端，没有必要为 WebSockets 使用 JavaScript 库。实现 WebSockets 的 Web 浏览器将通过 WebSockets 对象公开所有必需的客户端功能（主要指支持 Html5 的浏览器）。
客户端 API
以下 API 用于创建 WebSocket 对象。
因此，工程师们一直在思考，有没有更好的方法。WebSocket 就是这样发明的。WebSocket 连接允许客户端和服务器之间进行全双工通信，以便任一方都可以通过建立的连接将数据推送到另一端。WebSocket 只需要建立一次连接，就可以一直保持连接状态。这相比于轮询方式的不停建立连接显然效率要大大提高。
var Socket = new WebSocket(url, [protocol] );
WebSocket 属性
以下是 WebSocket 对象的属性。假定我们使用了以上代码创建了 Socket 对象：
WebSocket 事件
以下是 WebSocket 对象的相关事件。假定我们使用了以上代码创建了 Socket 对象：
WebSocket 方法
以下是 WebSocket 对象的相关方法。假定我们使用了以上代码创建了 Socket 对象：
示例一：websocket+tornado实现聊天室
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> <style> body{ background-color: black; } .container{ border:2px solid #dddddd; height: 400px; overflow: auto; } </style> </head> <body> <div style=" 750px;margin: 0 auto;background-color: #dddddd"> <h1 style="background-color: lawngreen">1024聊天室</h1> <div class="container"></div> <div class="input"> <input class="name" style=" 50px;height: 15px;" type="text" value="游客"> <input type="text" id="txt"> <input type="button" id="btn" value="发送" onclick="sendMessage()"> <input type="button" id="close" value="关闭连接" onclick="closeConn()"/> </div> <div id="content"></div> </div> <script src="/static/jquery-2.1.4.min.js"></script> <script> $(function () { wsUpdater.start(); }); var wsUpdater = { socket: null, name: null, start: function() { var url = "ws://127.0.0.1:8888/chat"; wsUpdater.socket = new WebSocket(url); wsUpdater.socket.onopen = function () { /* 与服务器端连接成功后，自动执行 */ var newTag = document.createElement('div'); newTag.innerHTML = "【连接成功】"; document.getElementById('content').appendChild(newTag); }; wsUpdater.socket.onmessage = function(event) { console.log(event); if(wsUpdater.name){ wsUpdater.showMessage(event.data); }else{ wsUpdater.name = event.data; } } }, showMessage: function(content) { $('.container').append(content); } }; function closeConn() { /* 服务器端主动断开连接时，自动执行 */ if (confirm("您确定要关闭本页吗？")){ // 旧方法 {#window.opener=null;#} {#window.open('','_self');#} {#window.close();#} // 新方法 window.location.href="about:blank"; window.close(); } else{} }; $("#txt").keydown(function (e) {//当按下按键时 if (e.which == 13) {//.which属性判断按下的是哪个键，回车键的键位序号为13 $('#btn').trigger("click");//触发搜索按钮的点击事件 } }); function sendMessage() { var msg = { name:$(".name").val(), message: $("#txt").val() }; wsUpdater.socket.send(JSON.stringify(msg)); } </script> </body> </html>
# -*- coding: utf-8 -*-
"""
@Datetime: 2018/8/28
@Author: Zhang Yafei
"""
import json
import uuid
import tornado.web
import tornado.ioloop
import tornado.websocket
class IndexHandler(tornado.web.RequestHandler):
def get(self, *args, **kwargs):
self.render('index.html')
class ChatHandler(tornado.websocket.WebSocketHandler):
users = set()
messages = []
def open(self, *args, **kwargs):
"""
客户端和服务器已经建立连接
1.连接
2.握手
:param args:
:param kwargs:
:return:
"""
ChatHandler.users.add(self)
# uid = str(uuid.uuid4())
# self.write_message(uid)
# for msg in ChatHandler.messages:
# content = self.render_string('message.html', **msg)
# self.write_message(content)
def on_message(self, message):
msg = json.loads(message)
ChatHandler.messages.append(message)
for client in ChatHandler.users:
content = self.render_string('message.html',**msg)
client.write_message(content)
def on_close(self):
"""
客户端主动关闭连接
:return:
"""
ChatHandler.users.remove(self)
def run():
settings = {
'template_path': 'templates',
'static_path': 'static',
}
application = tornado.web.Application([
(r"/", IndexHandler),
(r"/chat", ChatHandler),
], **settings)
application.listen(8888)
tornado.ioloop.IOLoop.instance().start()
if __name__ == "__main__":
run()
1024聊天室效果图
示例二：websocket+flask实现实时投票系统
<!DOCTYPE html> <html lang="zh-CN"> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1"> <!-- 上述3个meta标签*必须*放在最前面，任何其他内容都*必须*跟随其后！ --> <meta name="description" content=""> <meta name="author" content=""> <title>投票系统</title> <!-- Bootstrap core CSS --> <link href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"> <!-- IE10 viewport hack for Surface/desktop Windows 8 bug --> <link href="static/css/ie10-viewport-bug-workaround.css" rel="stylesheet"> <link href="static/plugins/font-awesome-4.7.0/css/font-awesome.min.css" rel="stylesheet"> <!-- Custom styles for this template --> <link href="static/css/dashboard.css" rel="stylesheet"> <script src="static/js/ie-emulation-modes-warning.js"></script> </head> <body> <nav class="navbar navbar-inverse navbar-fixed-top"> <div class="container-fluid"> <div class="navbar-header"> <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar"> <span class="sr-only">Toggle navigation</span> <span class="icon-bar"></span> <span class="icon-bar"></span> <span class="icon-bar"></span> </button> <a class="navbar-brand" href="#">投票系统</a> </div> <div id="navbar" class="navbar-collapse collapse"> <ul class="nav navbar-nav navbar-right"> <li><a class="item" href="#">消息<i style="margin-left: 3px;" class="fa fa-bell-o" aria-hidden="true"></i> <span class="badge" style="background-color: red">4</span></a> </li> <li><a class="item" href="#">通知<i style="margin-left: 3px;" class="fa fa-envelope-o" aria-hidden="true"></i> <span class="badge" style="background-color:forestgreen">4</span></a> </li> <li><a class="item" href="#">任务<i style="margin-left: 3px;" class="fa fa-commenting-o" aria-hidden="true"></i> <span class="badge" style="background-color: forestgreen">4</span></a> </li> <li><a href="https://v3.bootcss.com/examples/dashboard/#"></a></li> <li class="dropdown"> <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">张亚飞 <span class="caret"></span></a> <ul class="dropdown-menu"> <li><a href="#">个人信息</a></li> <li><a href="#">退出</a></li> </ul> </li> </ul> <form class="navbar-form navbar-right"> <input type="text" class="form-control" placeholder="Search..."> </form> </div> </div> </nav> <div class="row"> <div class="col-sm-3 col-md-2 sidebar"> <ul class="nav nav-sidebar"> <li class="active"><a href="#">投票系统<span class="sr-only">(current)</span></a></li> </ul> </div> <div class="col-sm-9 col-sm-offset-3 col-md-10 col-md-offset-2 main"> <h1 class="page-header">候选人</h1> <button style="position: absolute;right: 115px;top: 25px;" class="btn btn-success" onclick="closeConn()">关闭连接 </button> <ul id="userList" class="row placeholders"> {% for key,val in users.items() %} <div class="col-xs-6 col-sm-3 placeholder"> <img src="{{ val['image'] }}" width="200" height="200" class="img-responsive" alt="Generic placeholder thumbnail"> <h4> {{ val['name'] }} <span class="badge" id="id_{{ key }}" style="background-color: red">{{ val['count'] }}</span> </a> </h4> <li onclick="vote({{ key }})" class="text-muted btn btn-primary">投票</li> </div> {% endfor %} </ul> </div> </div> </div> </div> <!-- Bootstrap core JavaScript ================================================== --> <!-- Placed at the end of the document so the pages load faster --> <script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script> <script>window.jQuery || document.write('<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>')</script> <script src="https://cdn.bootcss.com/twitter-bootstrap/4.2.1/js/bootstrap.min.js"></script> <!-- Just to make our placeholder images work. Don't actually copy the next line! --> <script src="static/js/holder.min.js"></script> <!-- IE10 viewport hack for Surface/desktop Windows 8 bug --> <script src="static/js/ie10-viewport-bug-workaround.js"></script> <script> var ws = new WebSocket('ws://192.168.43.254:5000/message') ws.onmessage = function (event) { /* 服务器端向客户端发送数据时，自动执行 */ // {'cid':cid,'count':new} var response = JSON.parse(event.data); $('#id_' + response.cid).text(response.count); }; function vote(cid) { ws.send(cid); } function closeConn() { /* 服务器端主动断开连接时，自动执行 */ if (confirm("您确定要关闭本页吗？")){ window.location.href="about:blank"; window.close(); } else{} }; </script> </body> </html>
# -*- coding: utf-8 -*- """ @Datetime: 2019/1/9 @Author: Zhang Yafei """ from flask import Flask,render_template,request from geventwebsocket.handler import WebSocketHandler from gevent.pywsgi import WSGIServer import json app = Flask(__name__) USERS = { '1':{'name':'姚明','count':1,'image':'static/images/姚明.jpg'}, '2':{'name':'詹姆斯','count':0,'image':'static/images/詹姆斯.jpg'}, '3':{'name':'科比','count':0,'image':'static/images/科比.jpg'}, } # http://127.0.0.1:5000/index @app.route('/index') def index(): return render_template('home.html',users=USERS) # http://127.0.0.1:5000/message WEBSOCKET_LIST = [] @app.route('/message') def message(): ws = request.environ.get('wsgi.websocket') # ws为空表示http请求，否则为websocket请求 if not ws: print('http') return '您使用的是Http协议' WEBSOCKET_LIST.append(ws) while True: cid = ws.receive() if not cid: WEBSOCKET_LIST.remove(ws) ws.close() break old = USERS[cid]['count'] new = old + 1 USERS[cid]['count'] = new for client in WEBSOCKET_LIST: client.send(json.dumps({'cid':cid,'count':new})) if __name__ == '__main__': # http协议走app， websocket协议走websocket http_server = WSGIServer(('0.0.0.0', 80), app, handler_class=WebSocketHandler) http_server.serve_forever()
投票系统效果图
手动实现websocket
# -*- coding: utf-8 -*- """ @Datetime: 2018/8/28 @Author: Zhang Yafei """ import base64 import hashlib import socket import struct def send_msg(conn, msg_bytes): token = b"x81" length = len(msg_bytes) if length < 126: token += struct.pack("B", length) elif length <= 0xFFFF: token += struct.pack("!BH", 126, length) else: token += struct.pack("!BQ", 127, length) msg = token + msg_bytes conn.send(msg) return True def get_headers(data): """ 将请求头格式化成字典 :param data: :return: """ header_dict = {} data = str(data, encoding='utf-8') header, body = data.split(' ', 1) header_list = header.split(' ') for i in range(0, len(header_list)): if i == 0: if len(header_list[i].split(' ')) == 3: header_dict['method'], header_dict['url'], header_dict['protocol'] = header_list[i].split(' ') else: k, v = header_list[i].split(':', 1) header_dict[k] = v.strip() return header_dict sock = socket.socket(socket.AF_INET,socket.SOCK_STREAM) sock.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1) sock.bind(('127.0.0.1',8002)) sock.listen(5) #等待用户连接 conn,address = sock.accept() #握手消息 data = conn.recv(8096) headers = get_headers(data) # for k,v in headers.items(): # print(k,v) magic_string = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" value = headers['Sec-WebSocket-Key'] + magic_string ac = base64.b64encode(hashlib.sha1(value.encode('utf-8')).digest()) response_tpl = "HTTP/1.1 101 Switching Protocols " "Upgrade:websocket " "Connection:Upgrade " "Sec-WebSocket-Accept:%s " "WebSocket-Location:ws://%s%s " #获取握手消息，magic string.sha1加密 #发送回客户端 response_str = response_tpl % (ac.decode('utf-8'), headers['Host'], headers['url']) conn.send(bytes(response_str, encoding='utf-8')) while True: info = conn.recv(8096) payload_len = info[1] & 127 if payload_len == 126: extend_payload_len = info[2:4] mask = info[4:8] decoded = info[8:] elif payload_len == 127: extend_payload_len = info[2:10] mask = info[10:14] decoded = info[14:] else: extend_payload_len = None mask = info[2:6] decoded = info[6:] bytes_list = bytearray() for i in range(len(decoded)): chunk = decoded[i] ^ mask[i % 4] bytes_list.append(chunk) body = str(bytes_list, encoding='utf-8') body = body + '见到你很开心！' send_msg(conn,bytes(body,encoding='utf-8'))
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <script> ws = new WebSocket("ws://127.0.0.1:8002"); ws.onopen = function () { console.log('1111'); ws.send('hello 张亚飞') }; ws.onmessage = function (event) { console.log(event); }; ws.onclose = function () { } </script> </body> </html>
知识点
1. 什么是websocket？
是一套协议，协议规定了：
- 连接时需要握手
- 发送数据进行加密
- 连接之后不断开
2. websocket的意义？
实现服务段想客户端主动推送消息，实时通讯
3. websocket的兼容性是他的缺点。
4. 哪些框架支持websocket？
- flask，gevent-websocket
- django，channel
- torando框架自带
5. 应用场景？
实时响应页面时，可以使用websocket。
6. websocket实现原理
websocket原理： 1. 服务端运行，等待客户端连接 2. 小强来连接，服务端同意。 3. 小强立即发送一个“握手信息” GET /xxxx HTTP/1.1 Host: 127.0.0.1:8002 Connection: Upgrade Pragma: no-cache Cache-Control: no-cache Upgrade: websocket Origin: http://localhost:63342 Sec-WebSocket-Version: 13 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36 Accept-Encoding: gzip, deflate, br Accept-Language: zh-CN,zh;q=0.9 Cookie: csrftoken=ojyruuaF3Tk0OToIrXy1sRSdSk3SeDgd6Ti3jocEXAuEExaMtxjhJglpenj6Iq8F Sec-WebSocket-Key: 4NZY2fTOr691upgWe2yq7w== ######## 这里 ######## Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits 4. 服务端接收握手信息后需要对数据进行加密，给客户端返回 - 4NZY2fTOr691upgWe2yq7w + magic_string - sha1 - base64 response_tpl = "HTTP/1.1 101 Switching Protocols " "Upgrade:websocket " "Connection: Upgrade " "Sec-WebSocket-Accept: 加密之后的结果 " "WebSocket-Location: ws://127.0.0.1:8002 " 双方可以进行互相通信： 5. 小强给服务端发送消息： 读取第二个字节的后7位 127：10,4,数据 126：4,4,数据 <=125: 2,4,数据 6. 服务端给客户端发送消息： token = b"x81" length = len(msg_bytes) if length < 126: token += struct.pack("B", length) elif length <= 0xFFFF: token += struct.pack("!BH", 126, length) else: token += struct.pack("!BQ", 127, length)