Pyhton浅谈-Python与中间件之Redis(5)

Pyhton浅谈-Python与中间件之Redis(5) 

一、Redis也可以作为缓存中间件使用：

Redis是典型的NoSQL的代表，也可以使用Python操作Redis，在此不做过多介绍，见博客：https://www.cnblogs.com/catt1e/p/12565345.html，此博客主要介绍Redis作为缓存中间件；

二、Redis与Memcache的比较：

三、Python处理Redis：
　　此代码与上篇文章Memcache大同小异，但是Redis支持可以从不同的数据库中存取数据(代码中表现为db_type)，代码主要功能与上篇文章Python对于pymemcache的处理大同小异，在此不做赘述，直接看代码：、

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:catt1e


import time
import json
import redis


def get_data(db_type=‘tv‘):
    ‘‘‘获取数据
    1. 从mysql获取
    2. 从其他接口获取
    ‘‘‘
    data = None
    if db_type == ‘tv‘:
        data = {‘ch‘:[‘ch001‘,‘ch002‘], ‘mudan‘:[‘牡丹A‘,‘牡丹B‘]}
    elif db_type == ‘pc‘:
        data = {‘lenovo‘:[‘le-001‘,‘le-002‘], ‘dell‘:[‘dell-1‘,‘dell-2‘]}

    time.sleep(3)
    return data

def show_data(data):
    for k, v in data.items():
        print(k, v) 


def mid_cache(k, data, db_type="tv"):
    ‘‘‘缓存数据
    ‘‘‘
    try:
        client = None
        if db_type == ‘tv‘:
            client = redis.StrictRedis(host=‘localhost‘, port=6379, db=0)
        elif db_type == ‘pc‘:
            client = redis.StrictRedis(host=‘localhost‘, port=6379, db=1)

        ret = client.set(k, json.dumps(data))
        return ret
    except Exception as e:
        print(e)
        return False

redis_type = {
    "tv": 0,
    "pc": 1
}


    
def get_cache(k, db_type="tv"):
    ‘‘‘从k取缓存数据‘‘‘
    client = redis.StrictRedis(host=‘localhost‘, port=6379, db=redis_type[db_type])
    try:
        data = client.get(k)
        return json.loads(data)
    except Exception as e:
        print(e)
        return False



def main():
    k = ‘tv‘
    data = get_cache(k, db_type="pc")
    if data:
        print(‘from cache...‘)
        show_data(data)
    else:
        print(‘no data, 第一次取‘)
        data = get_data(db_type="pc")
        mid_cache(k, data,  db_type="pc")    

if __name__ == ‘__main__‘:
    main()

四、Redis订阅和发布功能：

1.订阅和发布功能：

 　　2.Pyhton操作Redis订阅和发布功能：

代码主要功能介绍：此代码分为redis_pub.py(发布端)和redis_sub.py(订阅端)两个，发布端可以在频道channels上发布信息，订阅端会监听发布端的消息，随后并输出所监听到的消息：

#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:catt1e
# redis_pub.py 发布端

 
import redis

client = redis.Redis()
channels = ["Jay", "SHE", ‘Beyond‘]

def main():
    print("可以发布到任意一个频道：")
    for i in channels:
        print(i)

    while True:
        ch = input("输入频道：")
        print("输入发送的信息(q：退出)：")
        msg = input(‘>>‘)
        if msg == ‘q‘:
            break
        client.publish(ch, msg) 


if __name__ == ‘__main__‘:
    main()






#!/usr/bin/env python
# -*- coding:utf-8 -*-
# Author:catt1e
# redis_sub.py订阅端

import redis

client = redis.StrictRedis()

channels = ["Jay", "SHE", ‘Beyond‘]

# 得到pubsub对象
# 通过对象订阅频道
# listen监听频道

def subscribe():
    s1 = client.pubsub()
    s1.subscribe(channels)

    s2 = client.pubsub()
    s2.subscribe(‘SHE‘)
 
    s3 = client.pubsub()
    s3.subscribe(channels[:2])

    show_msg(s1, ‘s1‘)
    show_msg(s2, ‘s2‘)
    show_msg(s3, ‘s3‘)


def show_msg(sub_obj, sub_name):
    for msg in sub_obj.listen():
        if msg["type"] == "message":
            print(f‘{sub_name} get {msg["data"].decode()} from {msg["channel"]}‘)


def main():
    subscribe()


if __name__ == ‘__main__‘:
    main()