一个简单的python MVC框架(1)

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一个简单的python MVC框架(1)

因为买了本机器学习的书是python的，所以学习了一下python，就用python做了一个简单的web开发的mvc小框架。整个框架分为实体层，数据访问层，业务基类层，Web请求转发层，控制层和视图层。当然也包括一些辅助性工具类。下面一一介绍，希望对跟我一样初学python的有点帮助：
1）实体层
      由实体基类和用户实体类组成。实体类可以由数据库自动生成，提供了一个DbTools，可以自动生成规则的实体。下面是实体基类：
    

import threading
#用户错误类，用于抛出自定义的异常
class CustomError(RuntimeError):def __init__(self,args):self.args=args
#实体的基类.          
class EntityB:def __init__(self):self.CurrFields=[]#根据属性名获取属性值def GetValueByName(self,FieldName):if hasattr(self,FieldName):return getattr(self,FieldName)return None#根据属性名设置属性值def SetValueByName(self,FieldName,Value):if hasattr(self,FieldName):return setattr(self,FieldName,Value)#定义了该属性，对象可枚举.def __getitem__(self,key):if type(key)==type('abc'):return self.GetValueByName(key)if type(key)==type(1):theFld = self.CurrFields[key]return self.GetValueByName(theFld)return None#设置属性值,key可以是索引，也可以是属性名.def __setitem__(self,key,value):if type(key)==type('abc'):self.SetValueByName(key,value)if type(key)==type(1):theFld = self.CurrFields[key]self.SetValueByName(theFld,value)#获取实体的表名.def GetTableName(self):theType = type(self)if hasattr(theType,'TableName'):return getattr(theType,'TableName')return ''#获取关键字段名def GetKeyField(self):theType = type(self)if hasattr(theType,'KeyField'):return getattr(theType,'KeyField')return ''#获取字段名集合def GetFields(self):theType = type(self)if hasattr(theType,'Fields'):return getattr(theType,'Fields')return []InsertCondition = threading.Condition()InsertLockSign = FalseDeleteCondition = threading.Condition()DeleteLockSign = FalseUpdateAllCondition = threading.Condition()UpdateAllLockSign = FalseInsertSqlName='__InsertSql'UpdateAllSqlName='__UpdateSql'DelByPKSqlName='__DelByPKSql'DefaultSelectSQL='__DefaultSelectSql'#根据属性名获取类型的属性值。def _GetClassValue(self,AttrName):theSelfType = type(self)theValue =''if hasattr(theSelfType,AttrName):theValue=getattr(theSelfType,AttrName)return theValue#根据属性名设置类型的属性值.def _SetClassValue(self,AttrName,value):theSelfType = type(self)theValue =''if hasattr(theSelfType,AttrName):setattr(theSelfType,AttrName,value)#获取字段参数def GetFieldParams(self):return self._GetClassValue('FieldParams')#获取插入的SQLdef GetInsertSQL(self):theSQL =self._GetClassValue(EntityB.InsertSqlName)if (theSQL==None or theSQL==''):EntityB.InsertCondition.acquire()try:if EntityB.InsertLockSign:EntityB.InsertCondition.wait()InsertLockSign = TruetheSQL =self._GetClassValue(EntityB.InsertSqlName)if (theSQL==None or theSQL==''):theTableName=self.GetTableName()theFields=self.GetFields()if theTableName=='' or theFields==[]:raise CustomError('表名或字段为空！')theSQL='INSERT INTO '+ theTableNametheFlds=''theVals=''theFldParams = self.GetFieldParams()for theF in theFields:if theFlds=='':theFlds += theFtheVals += theFldParams[theF]['DSFmt']else:theFlds += ','+theFtheVals +=','+theFldParams[theF]['DSFmt']theSQL+='('+theFlds+') values('+theVals+')'self._SetClassValue(EntityB.InsertSqlName,theSQL)return theSQLfinally:InsertLockSign=FalseEntityB.InsertCondition.notify()EntityB.InsertCondition.release()else:return theSQL#获取根据主键删除SQLdef GetDelByPKSQL(self):theSQL =self._GetClassValue(EntityB.DelByPKSqlName)if (theSQL==None or theSQL==''):EntityB.DeleteCondition.acquire()try:if EntityB.DeleteLockSign:EntityB.DeleteCondition.wait()DeleteLockSign = TruetheSQL =self._GetClassValue(EntityB.DelByPKSqlName)if (theSQL==None or theSQL==''):theTableName=self.GetTableName()theKeyField=self.GetKeyField()if theTableName=='' or theKeyField=='':raise CustomError('表名或主键为空！')theFldParams = self.GetFieldParams()theSQL='DELETE FROM '+ theTableName+' WHERE '+theKeyField+'='+theFldParams[theKeyField]['DSFmt']self._SetClassValue(EntityB.DelByPKSqlName,theSQL)return theSQLfinally:DeleteLockSign=FalseEntityB.DeleteCondition.notify()EntityB.DeleteCondition.release()else:return theSQL#获取更新所有字段的SQL语句(根据主键更新)def GetUpdateAllSQL(self):theSQL =self._GetClassValue(EntityB.UpdateAllSqlName)if (theSQL==None or theSQL==''):EntityB.UpdateAllCondition.acquire()try:if EntityB.UpdateAllLockSign:EntityB.UpdateAllCondition.wait()UpdateAllLockSign = TruetheSQL =self._GetClassValue(EntityB.UpdateAllSqlName)if (theSQL==None or theSQL==''):theTableName=self.GetTableName()theFields=self.GetFields()theKeyField=self.GetKeyField()if theTableName=='' or theFields==[] or theKeyField=='':raise CustomError('表名、主键或字段为空！')theSQL='UPDATE '+ theTableName +' SET 'theFlds=''theFldParams = self.GetFieldParams()for theF in theFields:if(theF != theKeyField):if theFlds=='':theFlds += theF+'= '+theFldParams[theF]['DSFmt']else:theFlds += ','+theF+'= '+theFldParams[theF]['DSFmt']theSQL+= theFlds +' WHERE '+theKeyField+'='+theFldParams[theKeyField]self._SetClassValue(EntityB.UpdateAllSqlName,theSQL)return theSQLfinally:UpdateAllLockSign=FalseEntityB.UpdateAllCondition.notify()EntityB.UpdateAllCondition.release()else:return theSQL#获取缺省的查询SQLdef GetDefaultSelectSQL(self):theTableName=self.GetTableName()return 'SELECT * FROM ' + theTableName + ' WHERE 1=1'#def __delitem__(self)

有关实体的通用操作SQL都是动态产生的，但不是每次都去产生，而是缓存在类型下。所为实体，做如下建议：
1）通用的SQL可以先产生，或者动态产生，但缓存；
2）一般查询SQL，特别是带条件的，尽量不要动态产生，也不要使用类似EF框架的那种，无论是管理性能还是扩展都是灾难；
3）一般不要把实体关系固化，如早期Hibernate的那种方式，就是在数据库里也不要建外间关系，去根据业务需要转化为业务逻辑，一般系统大一点，或者在分布式结构下，去固化实体关系，或者把实体关系映射放到内存或者配置文件中，都是一种灾难。

下面的类是辅助工具类：

#Generate entities
import BusinessBase
def GetFmtStr(datatype):if datatype.find('varchar')>=0:return '%s'elif datatype.find('date')>=0:return '%s'else:return '%s'
def IntToStr(iData=0):if iData==None:return '0'return '%d' % iData;
theFile = open(r"EntitiesL.py", "w")
try:theDb = BusinessBase.BusinessBase(object)#这里需改为从你自己的数据库XXXXtheTabs = theDb.GetDbTables('XXXX')theFile.write("import EntityBase\n")for theTab in theTabs:theFile.write('class M_'+theTab.TableName.upper()+'(EntityBase.EntityB):\n')theFile.write('    def __init__(self):\n')theFile.write('        M_'+theTab.TableName.upper()+'.Count += 1\n')theFile.write('        self.RefDict={}\n')theFile.write('        self.CurrFields=[]\n')theFile.write('    Count=0\n')    theFile.write('    TableName =\''+theTab.TableName+'\'\n')theKeyField=''theFlds=''theFile.write('    FieldParams={\n') theFields=theDb.GetTabFields('tian',theTab.TableName)theIndex =0for theF in theFields:if theF.iskey==1:theKeyField = theF.column_nametheIndex += 1if(theIndex>1):theFile.write('                        ,\n')theFlds+=',\''+theF.column_name+'\''else:theFlds='\''+theF.column_name+'\''theFile.write('                  \''+theF.column_name+'\':\n')theFile.write('                        {\n')theFile.write('                        \'DSFmt\':\''+GetFmtStr(theF.data_type)+'\',\n')theFile.write('                        \'DataType\':\''+theF.data_type+'\',\n')theFile.write('                        \'Length\':'+IntToStr(theF.lengthb)+',\n')theFile.write('                        \'Precision\':'+IntToStr(theF.precisionlen)+',\n')theFile.write('                        \'Scale\':'+IntToStr(theF.scalelen)+'\n')theFile.write('                        }\n')theFile.write('                }\n')theFile.write('    KeyField =\''+theKeyField+'\'\n')theFile.write('    Fields =['+theFlds+']\n')finally:theFile.close()

#这个类用于获取对象的自定义属性。

import inspect
import types
class ObjOpt:@staticmethoddef IsProperty(obj):if(obj.__class__ is types.FunctionType):return Falseelse:return True@staticmethoddef GetPropertyNames(obj):theAttrs = inspect.getmembers(obj,ObjOpt.IsProperty)theRetAttrs = []for attr in theAttrs:bb=attr[0].startswith('__')if bb==False:theRetAttrs.append(attr[0])return theRetAttrs;#获取类名@staticmethoddef GetClassName(Obj):return Obj.__name__

这是一个自动生成的实体类例子：

class M_SS01_SYS_USR(EntityBase.EntityB):def __init__(self):M_SS01_SYS_USR.Count += 1self.RefDict={}self.CurrFields=[]Count=0TableName ='SS01_SYS_USR'KeyField='USR_ID'Fields=['USR_ID','USR_NAME','USR_PWD']FieldParams={'USR_ID':{'DSFmt':'%s','DataType':'varchar','Length':50,'Precision':0,'Scale':0},'USR_NAME':{'DSFmt':'%s','DataType':'varchar','Length':50,'Precision':0,'Scale':0},'USR_PWD':{'DSFmt':'%s','DataType':'varchar','Length':50,'Precision':0,'Scale':0}}