django17：importlib应用中间件代码思想_task_cls = getattr(pkg), cls_name)‘

转载：https://www.cnblogs.com/alice-bj/articles/9276880.html

背景

仿django的中间件的编程思想

用户可通过配置，选择是否启用某个组件/某个功能，只需要配置

eg:报警系统，发邮件，发微信 。。。

( 根据字符串导入模块， 利用反射找到模块下的类，实例化。执行 )

code

# settings.py
 
NOTIFY_LIST = [
    'notify.email.Email',
    'notify.msg.Msg',
    'notify.wechat.Wechat',
]
 
-----------------------------
 
# app.py
 
from notify import send_xxx
 
def run():
    send_xxx("报警")
 
if __name__ == "__main__":
    run()
 
----------------------------
 
# notify/__init__.py
 
# 根据字符串 导入模块
 
import settings
import importlib
 
def send_xxx(content):
    for path in settings.NOTIFY_LIST:
        # 'notify.email.Email',
        # 'notify.msg.Msg',
        # 'notify.wechat.Wechat',
        module_path,class_name = path.rsplit('.',maxsplit=1)
        # 根据字符串导入模块
        module = importlib.import_module(module_path)
        # 根据类名称去模块中获取类
        cls = getattr(module,class_name)
        # 根据类实例化
        obj = cls()
        obj.send(content)
 
 
-----------------------------
 
 
 
# notify/email.py
 
class Email(object):
    def __init__(self):
        pass
 
    def send(self,content):
        print("email send..")
 
 
# notify/msg.py
 
class Msg(object):
    def __init__(self):
        pass
 
    def send(self,content):
        print("msg send..")
 
 
# notify/wechat.py
 
class Wechat(object):
    def __init__(self):
        pass
 
    def send(self,content):
        print("wechat send..")