flask 5

websocket介绍与使用

1.websocket 与轮询

轮询：
不断向服务器发起询问，服务器还不断的回复
浪费带宽，浪费前后端资源
保证数据的实时性

长轮询：
1.客户端向服务器发起消息，服务端轮询，放在另外一个地方，客户端去另外一个地方去拿
2.服务端轮询，放在另外一个地方，直接推给客户端

释放客户端资源，服务压力不可避免，节省带宽资源
数据不能实时性

websocket：是一个新的协议 Socket-io
1.前后端hold住
2.建立长链接

彻底解决实时性
解决占用带宽的问题
解决资源　

2.webscoket使用

from flask import Flask, requesfrom geventwebsocket.websocket import WebSocket

from gevent.pywsgi import WSGIServer
from geventwebsocket.handler import WebSocketHandler

app = Flask(__name__)


@app.route("/ws") # WS://127.0.0.1:9527/ws
def ws():
# request.environ["wsgi.websocket"] = <链接>
user_socket = request.environ.get("wsgi.websocket") # type:WebSocket
while 1:
msg = user_socket.receive()
print(msg)
user_socket.send(msg)


if __name__ == '__main__':
http_serv = WSGIServer(("0.0.0.0", 9527), app, handler_class=WebSocketHandler)
http_serv.serve_forever()
# app.run("0.0.0.0", 9527, debug=True)

即时通讯(IM)：
群聊：
from flask import Flask, request,render_template
from geventwebsocket.websocket import WebSocket
from gevent.pywsgi import WSGIServer
from geventwebsocket.handler import WebSocketHandler
import json

app = Flask(__name__)

user_socket_dict = {} # {jinwangba:<geventwebsocket.websocket.WebSocket object at 0x000000000B35CE18>}

@app.route("/")
def index():
return render_template("index.html")

@app.route("/ws/<nickname>") # WS://127.0.0.1:9527/ws
def ws(nickname):
user_socket = request.environ.get("wsgi.websocket") # type:WebSocket
if user_socket:
user_socket_dict[nickname]=user_socket
print(len(user_socket_dict))
else:
return render_template("index.html",message="请使用Websocket链接")
while 1:
msg = user_socket.receive()
for user_nick_name,socket in user_socket_dict.items(): # type:WebSocket
if user_socket != socket:
try:
socket.send(json.dumps({"sender":nickname,"msg":msg}))
except:
continue


if __name__ == '__main__':
http_serv = WSGIServer(("0.0.0.0",9527),app,handler_class=WebSocketHandler)
http_serv.serve_forever()
# app.run("0.0.0.0", 9527, debug=True)

单聊：
from flask import Flask, request,render_template
from geventwebsocket.websocket import WebSocket
from gevent.pywsgi import WSGIServer
from geventwebsocket.handler import WebSocketHandler
import json

app = Flask(__name__)

user_socket_dict = {} # {jinwangba:<geventwebsocket.websocket.WebSocket object at 0x000000000B35CE18>}

@app.route("/")
def index():
return render_template("index.html")

@app.route("/ws/<nickname>") # WS://127.0.0.1:9527/ws
def ws(nickname):
user_socket = request.environ.get("wsgi.websocket") # type:WebSocket
if user_socket:
user_socket_dict[nickname]=user_socket
print(len(user_socket_dict),user_socket_dict)
else:
return render_template("index.html",message="请使用Websocket链接")
while 1:
msg = user_socket.receive()
msg_dict = json.loads(msg)
#{"to_user":jinwangba,msg:"DSB"}
to_user = msg_dict.get("to_user")
print("to_user:",to_user)
to_user_socket = user_socket_dict.get(to_user)
send_str = json.dumps({"sender":nickname,"msg":msg_dict.get("msg")})
to_user_socket.send(send_str)


if __name__ == '__main__':
http_serv = WSGIServer(("0.0.0.0",9527),app,handler_class=WebSocketHandler)
http_serv.serve_forever()
# app.run("0.0.0.0", 9527, debug=True)

3.websocket 握手原理

magic string为：258EAFA5-E914-47DA-95CA-C5AB0DC85B11
握手返回信息：Sec-WebSocket-Key + magic string

import socket, base64, hashlib

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.bind(('127.0.0.1', 9527))
sock.listen(5)
# 获取客户端socket对象
conn, address = sock.accept()
# 获取客户端的【握手】信息
data = conn.recv(1024)
print(data)


def get_headers(data):
header_dict = {}
header_str = data.decode("utf8")
for i in header_str.split("\r\n"):
if str(i).startswith("Sec-WebSocket-Key"):
header_dict["Sec-WebSocket-Key"] = i.split(":")[1].strip()

return header_dict

ws_key = get_headers(data).get("Sec-WebSocket-Key")

# # magic string为：258EAFA5-E914-47DA-95CA-C5AB0DC85B11
magic_string = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'
socket_str = ws_key + magic_string
socket_str_sha1 = hashlib.sha1(socket_str.encode("utf8")).digest()
socket_str_base64 = base64.b64encode(socket_str_sha1)

response_tpl = "HTTP/1.1 101 Switching Protocols\r\n" \
"Upgrade:websocket\r\n" \
"Connection: Upgrade\r\n" \
"Sec-WebSocket-Accept: %s\r\n" \
"WebSocket-Location: ws://127.0.0.1:9527\r\n\r\n" %(socket_str_base64.decode("utf8"))

conn.send(response_tpl.encode("utf8"))
while 1:
msg = conn.recv(8096)
print(msg)