第二十章 Caché 設計模式 職責鏈模式

第二十章 Caché 設計模式 職責鏈模式

定義

使多個對象都有機會處理請求，從而避免請求發送者與接收者之間的耦合關係。將這個對象連成一條鏈，並沿着這條鏈傳遞該請求，知道有一個對象處理它爲止。

優點

• 請求者和處理者關係解耦，提高代碼靈活性。
• 當客戶提交一個請求時，請求是沿着鏈傳遞直至有一個ConcreteHandler對象負責處理它。
• 隨時地增加或修改處理一個請求的結構。增強了對象指派職責的靈活性。
• 接收者和發送者都沒有對象的明確信息，且鏈中的對象自己也並不知道鏈的結構，結果是職責鏈可簡化對象的相互連接，它們僅需保持一個指向其後繼承者的引用，而不需保持它所有的候選接受者的引用。

缺點

• 對處理者遍歷，弱處理者太多，會影響性能，特別在遞歸處理中尤其需要注意。

結構圖

描述

申請人，申請請假或加薪，隨着申請權限不同，扭轉不同管理者。

完整示例

請求類

Class PHA.YX.Design.Chain.Request Extends %RegisteredObject
{

Property requestType As %String;

Method requestTypeGet() As %String [ ServerOnly = 1 ]
{
	
	Quit i%requestType
}

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

Property requestContent As %String;

Method requestContentGet() As %String [ ServerOnly = 1 ]
{
	Quit i%requestContent
}

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

Property number As %String;

Method numberGet() As %String [ ServerOnly = 1 ]
{
	Quit i%number
}

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

}

抽象責任類

Class PHA.YX.Design.Chain.Manager Extends %RegisteredObject
{

Property name As %String;

Property superior As Manager;

Method %OnNew(name As %String) As %Status [ Private, ServerOnly = 1 ]
{
	s ..name = name
	Quit $$$OK
}

Method SetSuperior(superior As Manager)
{
	s ..superior = superior
}

Method RequertApplications(request As Request) [ Abstract ]
{
}

}

實現責任類

Class PHA.YX.Design.Chain.CommonManager Extends Manager
{

Method %OnNew(name As %String) As %Status [ Private, ServerOnly = 1 ]
{
	d ##super(name)
	Quit $$$OK
}

Method RequertApplications(request As Request)
{
	i (request.requestTypeGet() = "請假") && (request.numberGet() <= 2) d
	.w ..name _ ":" _ request.requestContentGet() _ "數量" _ request.numberGet() _ "被批准",!
	e  d
	.i ..superior '= "" d
	..d ..superior.RequertApplications(request)
}

}

Class PHA.YX.Design.Chain.MajorManager Extends Manager
{

Method %OnNew(name As %String) As %Status [ Private, ServerOnly = 1 ]
{
	d ##super(name)
	Quit $$$OK
}

Method RequertApplications(request As Request)
{
	i (request.requestTypeGet() = "請假") && (request.numberGet() <= 5) d
	.w ..name _ ":" _ request.requestContentGet() _ "數量" _ request.numberGet() _ "被批准",!
	e  d
	.i ..superior '= "" d
	..d ..superior.RequertApplications(request)
}

}

Class PHA.YX.Design.Chain.GeneralManager Extends Manager
{

Method %OnNew(name As %String) As %Status [ Private, ServerOnly = 1 ]
{
	d ##super(name)
	Quit $$$OK
}

Method RequertApplications(request As Request)
{
	i (request.requestTypeGet() = "請假") d
	.w ..name _ ":" _ request.requestContentGet() _ " 數量" _ request.numberGet() _ "被批准",!
	e  i (request.requestTypeGet() = "加薪") && (request.numberGet() <=500) d
	.w ..name _ ":" _ request.requestContentGet() _ " 數量" _ request.numberGet() _ "被批准",!
	e  i (request.requestTypeGet() = "加薪") && (request.numberGet() >500) d
	.w ..name _ ":" _ request.requestContentGet() _ " 數量" _ request.numberGet() _ "再說吧",!
}

}

調用

/// d ##class(PHA.YX.Design.Program).Chain() 
ClassMethod Chain()
{
	s zz = ##class(PHA.YX.Design.Chain.CommonManager).%New("周總")
	s sz = ##class(PHA.YX.Design.Chain.MajorManager).%New("蘇總")
	s hz = ##class(PHA.YX.Design.Chain.GeneralManager).%New("韓總")

	d zz.SetSuperior(sz)
	d sz.SetSuperior(hz)
	
	s request = ##class(PHA.YX.Design.Chain.Request).%New()
	d request.numberSet(1)
	d request.requestContentSet("丁竑瑩請假")
	d request.requestTypeSet("請假")
	d zz.RequertApplications(request)
	
	s request1 = ##class(PHA.YX.Design.Chain.Request).%New()
	d request1.numberSet(4)
	d request1.requestContentSet("小馬哥請假")
	d request1.requestTypeSet("請假")
	d zz.RequertApplications(request1)
	
	s request2 = ##class(PHA.YX.Design.Chain.Request).%New()
	d request2.numberSet(500)
	d request2.requestContentSet("姚鑫請求加薪")
	d request2.requestTypeSet("加薪")
	d zz.RequertApplications(request2)
	
	s request3 = ##class(PHA.YX.Design.Chain.Request).%New()
	d request3.numberSet(1000)
	d request3.requestContentSet("姚鑫請求加薪")
	d request3.requestTypeSet("加薪")
	d zz.RequertApplications(request3)
}

DHC-APP>d ##class(PHA.YX.Design.Program).Chain()
周總:丁竑瑩請假數量1被批准
蘇總:小馬哥請假數量4被批准
韓總:姚鑫請求加薪 數量500被批准
韓總:姚鑫請求加薪 數量1000再說吧

思考

英雄聯盟，黑鐵，青銅，白銀，黃金，鉑金，鑽石，大師，王者。請求者爲對應級別纔可以匹配，否則扭轉。