第十一章 Caché 設計模式 抽象工廠模式

第十一章 Caché 設計模式 抽象工廠模式

定義

提供一個創建一系列相關或相互依賴的接口，而無需制定它們具體的類。

優點

• 相比與簡單工廠，沒有違背開放封閉原則。
• 可直接創建產品即可。

結構圖

描述

連接數據庫SQL和Caché並且每個數據庫映射的同張的表的類型是不同的。

完整示例

實體類

Class PHA.YX.Design.AbstractFactory.User Extends %RegisteredObject
{

Property ID As %String;

Method IDGet() As %String [ ServerOnly = 1 ]
{
	Quit i%ID
}

Method IDSet(Arg As %String) As %Status [ ServerOnly = 1 ]
{
	s i%ID = Arg
	Quit $$$OK
}

Property name As %String;

Method nameGet() As %String [ ServerOnly = 1 ]
{
	Quit i%name
}

Method nameSet(Arg As %String) As %Status [ ServerOnly = 1 ]
{
	s i%name = Arg
	Quit $$$OK
}

}

Class PHA.YX.Design.AbstractFactory.Department Extends %RegisteredObject
{

Property ID As %String;

Method IDGet() As %String [ ServerOnly = 1 ]
{
	Quit i%ID
}

Method IDSet(Arg As %String) As %Status [ ServerOnly = 1 ]
{
	s i%ID = Arg
	Quit $$$OK
}

Property name As %String;

Method nameGet() As %String [ ServerOnly = 1 ]
{
	Quit i%name
}

Method nameSet(Arg As %String) As %Status [ ServerOnly = 1 ]
{
	s i%name = Arg
	Quit $$$OK
}

}

抽象產品類

Class PHA.YX.Design.AbstractFactory.IDepartment Extends %RegisteredObject
{

Method Insert(department As Department)
{
}

Method GetDepartment(ID As %Integer)
{
}

}

Class PHA.YX.Design.AbstractFactory.IUser Extends %RegisteredObject
{

Method Insert(user As User)
{
}

Method GetUser(ID As %Integer)
{
}

}

具體產品類

User

Class PHA.YX.Design.AbstractFactory.SqlUser Extends IUser
{

Method Insert(user As User)
{
	w "在SQL中給User表添加一條記錄",!
}

Method GetUser(ID As %Integer)
{
	w "在SQL中根據ID得到User表一條記錄",!
}

ClassMethod CreatObject()
{
	q ##class(PHA.YX.Design.AbstractFactory.SqlUser).%New()
}

}

Class PHA.YX.Design.AbstractFactory.CacheUser Extends IUser
{

Method Insert(user As User)
{
	w "在Cache中給User表添加一條記錄",!
}

Method GetUser(ID As %Integer)
{
	w "在Cache中根據ID得到User表一條記錄",!
}

ClassMethod CreatObject()
{
	q ##class(PHA.YX.Design.AbstractFactory.CacheUser).%New()
}

}

Department

Class PHA.YX.Design.AbstractFactory.SqlDepartment Extends IDepartment
{

Method Insert(department As Department)
{
	w "在SQL中給Department表添加一條記錄",!
}

Method GetDepartment(ID As %Integer)
{
	w "在SQL中根據ID得到Department表一條記錄",!
}

ClassMethod CreatObject()
{
	q ##class(PHA.YX.Design.AbstractFactory.SqlDepartment).%New()
}

}

Class PHA.YX.Design.AbstractFactory.CacheDepartment Extends IDepartment
{

Method Insert(department As Department)
{
	w "在Cache中給Department表添加一條記錄",!
}

Method GetDepartment(ID As %Integer)
{
	w "在Cache中根據ID得到Department表一條記錄",!
}

ClassMethod CreatObject()
{
	q ##class(PHA.YX.Design.AbstractFactory.CacheDepartment).%New()
}

}

抽象工廠類

• 因爲Caché 系統$反射方法沒有創建對象的方法。所以採用了一種討巧的方式.
  • $classmethod 可以直接調用靜態方法。
  • 通過給實體類創建一個靜態方法返回該對象的實例。
• 直接用XECUTE命令直接反射，然後獲取引用對象。
• 配置的字符串可以通過inc文件來制定，符合開放封閉原則，又可配置。

注意：本章使用的反射+配置實現訪問程序

Include PHA.YX.Design.AbstractFactory.Data

Class PHA.YX.Design.AbstractFactory.DataAccess Extends %RegisteredObject
{

Parameter sqlDatabase = "Sql";

Parameter cacheDatabase = "Cache";

ClassMethod CreateUser() As IUser
{
	# dim mUser as PHA.YX.Design.AbstractFactory.IUser
	s classNmae = "PHA.YX.Design.AbstractFactory." _ ..#sqlDatabase _ "User"
	s mUser = $classmethod(classNmae,"CreatObject")
	q mUser
}

ClassMethod CreateDepartment() As IDepartment
{
	# dim mUser as PHA.YX.Design.AbstractFactory.IDepartment
	s classNmae = "PHA.YX.Design.AbstractFactory." _ ..#sqlDatabase _ "Department"
	s mUser = $classmethod(classNmae,"CreatObject")
	q mUser
}

ClassMethod CreateUserTwo() As IUser
{
	# dim mUser as PHA.YX.Design.AbstractFactory.IUser
	s classNmae = "PHA.YX.Design.AbstractFactory." _ $$$database _ "User"
	x ("(mUser) s mUser = ##class(" _ classNmae _ ").%New()", .mUser)
	q mUser
}

}

#define database "Cache"

思考

改寫第一章思考生產電腦的例子。感興趣的同學實現後可以發我一起參考下。