用ASP、VB和XML建立互聯(lián)網(wǎng)應用程序(4)
2024-09-05 20:55:54
供稿：網(wǎng)友
前面我們已經(jīng)介紹了使用asp和xml混合編程，那是因為asp頁面能夠很容易讓我們看清應用程序正在做什么，但是你如果你不想使用asp的話，你也可以使用任何你熟悉的技術(shù)去創(chuàng)建一個客戶端程序。下面，我提供了一段vb代碼，它的功能和asp頁面一樣，也可以顯示相同的數(shù)據(jù)，但是這個vb程序不會創(chuàng)建發(fā)送到服務器的xml字符串。它通過運行一個名叫initialize的存儲過程，從服務器取回xml字符串，來查詢clientcommands表的內(nèi)容。
clientcommands表包括兩個域：command_name域和command_xml域?？蛻舳顺绦蛐枰齻€特定的command_name域:getcustomerlist,custorderhist和recentpurchasebycustomerid。每一個命令的command_xml域包括程序發(fā)送到getdata.asp頁面的xml字符串，這樣，就可以集中控制xml字符串了，就象存儲過程名字所表現(xiàn)的意思一樣，在發(fā)送xml字符串到getdata.asp之前，客戶端程序使用xml dom來設(shè)置存儲過程的參數(shù)值。我提供的代碼，包含了用于定義initialize過程和用于創(chuàng)建clientcommands表的sql語句。
我提供的例程中還說明了如何使用xhttprequest對象實現(xiàn)我在本文一開始時許下的承諾:任何遠程的機器上的應用程序都可以訪問getdata.asp；當然，你也可以通過設(shè)置iis和ntfs權(quán)限來限制訪問asp頁面；你可以在服務器上而不是客戶機上存儲全局應用程序設(shè)置；你可以避免通過網(wǎng)絡(luò)發(fā)送數(shù)據(jù)庫用戶名和密碼所帶來的隱患性。還有，在ie中，應用程序可以只顯示需要的數(shù)據(jù)而不用刷新整個頁面。
在實際的編程過程中，你們應當使用一些方法使應用程序更加有高效性。你可以把asp中的關(guān)于取得數(shù)據(jù)的代碼端搬到一個com應用程序中去然后創(chuàng)建一個xslt變換來顯示返回的數(shù)據(jù)。好，我不多說了，現(xiàn)在你所要做的就是試一試吧！
option explicit
private rcommands as recordset
private rcustomers as recordset
private rcust as recordset
private scustlistcommand as string
private const dataurl = "http://localhost/xhttprequest/getdata.asp"
private arrcustomerids() as string
private enum actionenum
view_history = 0
view_recent_product = 1
end enum
private sub dgcustomers_click()
dim customerid as string
customerid = rcustomers("customerid").value
if customerid ＜＞ "" then
if optaction(view_history).value then
call getcustomerdetail(customerid)
else
call getrecentproduct(customerid)
end if
end if
end sub
private sub form_load()
call initialize
call getcustomerlist
end sub
sub initialize()
' 從數(shù)據(jù)庫返回命令名和相應的值
dim sxml as string
dim vret as variant
dim f as field
sxml = "＜?xml version=""1.0""?＞"
sxml = sxml & "＜command＞＜commandtext＞initialize＜/commandtext＞"
sxml = sxml & "＜returnsdata＞true＜/returnsdata＞"
sxml = sxml & "＜/command＞"
set rcommands = getrecordset(sxml)
do while not rcommands.eof
for each f in rcommands.fields
debug.print f.name & "=" & f.value
next
rcommands.movenext
loop
end sub
function getcommandxml(command_name as string) as string
rcommands.movefirst
rcommands.find "command_name='" & command_name & "'", , adsearchforward, 1
if rcommands.eof then
msgbox "cannot find any command associated with the name '" & command_name & "'."
exit function
else
getcommandxml = rcommands("command_xml")
end if
end function
sub getrecentproduct(customerid as string)
dim sxml as string
dim xml as domdocument
dim n as ixmldomnode
dim productname as string
sxml = getcommandxml("recentpurchasebycustomerid")
set xml = new domdocument
xml.loadxml sxml
set n = xml.selectsinglenode("command/param[name='customerid']/value")
n.text = customerid
set xml = executespwithreturn(xml.xml)
productname = xml.selectsinglenode("values/productname").text
' 顯示text域
txtresult.text = ""
me.txtresult.visible = true
dgresult.visible = false
' 顯示product名
txtresult.text = "最近的產(chǎn)品是: " & productname
end sub
sub getcustomerlist()
dim sxml as string
dim i as integer
dim s as string
sxml = getcommandxml("getcustomerlist")
set rcustomers = getrecordset(sxml)
set dgcustomers.datasource = rcustomers
end sub
sub getcustomerdetail(customerid as string)
' 找出列表中相關(guān)聯(lián)的id號
dim sxml as string
dim r as recordset
dim f as field
dim s as string
dim n as ixmldomnode
dim xml as domdocument
sxml = getcommandxml("custorderhist")
set xml = new domdocument
xml.loadxml sxml
set n = xml.selectsinglenode("command/param[name='customerid']/value")
n.text = customerid
set r = getrecordset(xml.xml)
' 隱藏 text , 因為它是一個記錄集
txtresult.visible = false
dgresult.visible = true
set dgresult.datasource = r
end sub
function getrecordset(sxml as string) as recordset
dim r as recordset
