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 = False
DeleteCondition = threading.Condition()
DeleteLockSign = False
UpdateAllCondition = threading.Condition()
UpdateAllLockSign = False
InsertSqlName='__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SQL
def GetInsertSQL(self):
theSQL =self._GetClassValue(EntityB.InsertSqlName)
if (theSQL==None or theSQL==''):
EntityB.InsertCondition.acquire()
try:
if EntityB.InsertLockSign:
EntityB.InsertCondition.wait()
InsertLockSign = True
theSQL =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 '+ theTableName
theFlds=''
theVals=''
theFldParams = self.GetFieldParams()
for theF in theFields:
if theFlds=='':
theFlds += theF
theVals += theFldParams[theF]['DSFmt']
else:
theFlds += ','+theF
theVals +=','+theFldParams[theF]['DSFmt']
theSQL+='('+theFlds+') values('+theVals+')'
self._SetClassValue(EntityB.InsertSqlName,theSQL)
return theSQL
finally:
InsertLockSign=False
EntityB.InsertCondition.notify()
EntityB.InsertCondition.release()
else:
return theSQL
#获取根据主键删除SQL
def GetDelByPKSQL(self):
theSQL =self._GetClassValue(EntityB.DelByPKSqlName)
if (theSQL==None or theSQL==''):
EntityB.DeleteCondition.acquire()
try:
if EntityB.DeleteLockSign:
EntityB.DeleteCondition.wait()
DeleteLockSign = True
theSQL =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 theSQL
finally:
DeleteLockSign=False
EntityB.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 = True
theSQL =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 theSQL
finally:
UpdateAllLockSign=False
EntityB.UpdateAllCondition.notify()
EntityB.UpdateAllCondition.release()
else:
return theSQL
#获取缺省的查询SQL
def 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XXXX
theTabs = 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 =0
for theF in theFields:
if theF.iskey==1:
theKeyField = theF.column_name
theIndex += 1
if(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:
@staticmethod
def IsProperty(obj):
if(obj.__class__ is types.FunctionType):
return False
else:
return True
@staticmethod
def 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
@staticmethod
def 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 += 1
self.RefDict={}
self.CurrFields=[]
Count=0
TableName ='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
}
}