先把有問題的代碼曬一下：
IServer.py
from abc import ABCMeta, abstractmethodprint __name__class IServer: def __init__(self): pass @abstractmethod def DoWithA(self): pass @abstractmethod def DoWithB(self): pass
IServer_A.py
import IServerserverType ='1001'print __name__dir()from CreatFactory import GLOBAL_class_dicdir()class IServer_A(IServer.IServer): def __init__(self): pass def DoWithA(self): print 'Server_A do with interface A' def DoWithB(self): print 'Server_A do with interface B'global GLOBAL_class_dicprint 'the id of GLOBAL_class_dic in A is:',id(GLOBAL_class_dic)GLOBAL_class_dic[serverType] = IServer_Aprint 'GLOBAL_class_dic in a is:', GLOBAL_class_dic
IServer_B.py
import IServerserverType ='1002'from CreatFactory import GLOBAL_class_dicprint __name__class IServer_B(IServer.IServer): def __init__(self): pass def DoWithA(self): print 'Server_B do with interface A' def DoWithB(self): print 'Server_B do with interface B'print 'the id of GLOBAL_class_dic in B is:',id(GLOBAL_class_dic)GLOBAL_class_dic[serverType] = IServer_Bprint 'GLOBAL_class_dic in b is:', GLOBAL_class_dic
CreatFactory.py
#coding:UTF-8import os;import sys;import threadingfrom misc import *global GLOBAL_class_dicGLOBAL_class_dic ={1:1}print 'GLOBAL_class_dic in define is:', GLOBAL_class_dicprint 'the id of GLOBAL_class_dic in define is:', id(GLOBAL_class_dic)dir()import IServer_Aimport IServer_Bdef CreateServer(serverType): global GLOBAL_class_dic print 'GLOBAL_class_dic in use is:', GLOBAL_class_dic print 'the id of GLOBAL_class_dic in USE is:', id(GLOBAL_class_dic) if GLOBAL_class_dic.has_key(serverType): return GLOBAL_class_dic[serverType] else: return 'no'if __name__ == '__main__': pass # 接收到報文后，根據報文的內容，從db中獲取到serverType，假設獲取到的serverType=1001 print 'main' print 'GLOBAL_class_dic in main A is:', GLOBAL_class_dic serverType = '1002' server = CreateServer(serverType) print 'GLOBAL_class_dic in main B is:', GLOBAL_class_dic print 'server :',server server.DoWithA(server())代碼內已經加了調試的部分信息， 運行CreatFactory.py。調用DoWithA失敗，提示AttributeError: 'str' object has no attribute 'DoWithA'。運行結果如下：
D:/Python27/python.exe "D:/DesignMode/Server --00/CreatFactory.py"GLOBAL_class_dic in define is: {1: 1}the id of GLOBAL_class_dic in define is: 36230176['GLOBAL_class_dic', 'Misc', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'binascii', 'inspect', 'minidom', 'os', 'struct', 'sys', 'threading']IServerIServer_A['IServer', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'serverType']GLOBAL_class_dic in define is: {1: 1}the id of GLOBAL_class_dic in define is: 36230032['GLOBAL_class_dic', 'Misc', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'binascii', 'inspect', 'minidom', 'os', 'struct', 'sys', 'threading']['IServer', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'serverType']['GLOBAL_class_dic', 'IServer', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'serverType']IServer_Bthe id of GLOBAL_class_dic in B is: 36230032GLOBAL_class_dic in b is: {1: 1, '1002': <class IServer_B.IServer_B at 0x022C2ED8>}['GLOBAL_class_dic', 'IServer', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'serverType']the id of GLOBAL_class_dic in A is: 36230032GLOBAL_class_dic in a is: {1: 1, '1002': <class IServer_B.IServer_B at 0x022C2ED8>, '1001': <class IServer_A.IServer_A at 0x02273420>}mainGLOBAL_class_dic in main A is: {1: 1}GLOBAL_class_dic in use is: {1: 1}the id of GLOBAL_class_dic in USE is: 36230176GLOBAL_class_dic in main B is: {1: 1}server : noTraceback (most recent call last): File "D:/DesignMode/Server --00/CreatFactory.py", line 38, in <module> server.DoWithA(server())AttributeError: 'str' object has no attribute 'DoWithA'Process finished with exit code 1從運行的結果，可以看到：GLOBAL_class_dic 被定義了2次。有兩個不同的id，第一次定義分配了一塊內存，第二次不明原因的又重新分配了一塊內存，然后服務的自動注冊全部注冊在這塊內存中，等到main函數使用的使用，又使用的是第一次申請的內存，所以導致程序運行失敗。那問題就來了，為什么會被重新又分配了一次？
之所以會被重新定義一次全局變量，是因為在執行CreatFactory.py時，最開始定義了全局變量，此時該命名空間可使用的函數和變量打印：['GLOBAL_class_dic', 'Misc', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'binascii', 'inspect', 'minidom', 'os', 'struct', 'sys', 'threading'，然后在import IServer_A，在IServer_A.py中，import IServer后，在from CreatFactory import GLOBAL_class_dic打印出可使用的函數和變量時，['IServer', '__builtins__', '__doc__', '__file__', '__name__', '__package__', 'serverType']，就沒有GLOBAL_class_dic，程序發現沒有，就又重新聲明了一遍。似乎問題原因已經找到了。
python在導入的時候，有2種場景，一種就是在文件前普通的import語句，還有一種就是特殊的場景：__main__模塊是相對于Python的導入系統。在最開始運行CreatFactory.py文件時，__name__打印的值是__main__，而再子類再次導入時，會在當前命名空間查找是否已經導入__name__=CreatFactory，發現這個模塊不存在，故此又導入了一遍，全局變量由此又被重新定義分配了內存，后期全局變量在子類業務的使用就都使用該值，而在main函數里，使用的又是當前的作用域內的第一次定義的全局變量。
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