數(shù)據(jù)庫(kù)連接是一種關(guān)鍵的有限的昂貴的資源，這一點(diǎn)在多用戶的網(wǎng)頁(yè)應(yīng)用程序中體現(xiàn)得尤為突出。對(duì)數(shù)據(jù)庫(kù)連接的管理能顯著影響到整個(gè)應(yīng)用程序的伸縮性和健壯性，影響到程序的性能指標(biāo)。數(shù)據(jù)庫(kù)連接池正是針對(duì)這個(gè)問(wèn)題提出來(lái)的。數(shù)據(jù)庫(kù)連接池負(fù)責(zé)分配、管理和釋放數(shù)據(jù)庫(kù)連接，它允許應(yīng)用程序重復(fù)使用一個(gè)現(xiàn)有的數(shù)據(jù)庫(kù)連接，而再不是重新建立一個(gè)；釋放空閑時(shí)間超過(guò)最大空閑時(shí)間的數(shù)據(jù)庫(kù)連接來(lái)避免因?yàn)闆](méi)有釋放數(shù)據(jù)庫(kù)連接而引起的數(shù)據(jù)庫(kù)連接遺漏。這項(xiàng)技術(shù)能明顯提高對(duì)數(shù)據(jù)庫(kù)操作的性能。
但是這項(xiàng)技術(shù)一般在java ，php ，.net 里面運(yùn)用到，asp很少用到，因?yàn)橐恍┢髽I(yè)網(wǎng)站根本就不需要這樣的技術(shù)。
也不是不能使用，下面就是研究出來(lái)的asp版本，能夠加快網(wǎng)頁(yè)的訪問(wèn)速度，降低數(shù)據(jù)庫(kù)的壓力。
1.數(shù)據(jù)庫(kù)連接文件 DbPool.asp
< %
Const PoolSize = 10
Const Connstr = "Driver={SQL Server};Server=(local);UID=sa;word=555;Database=db"
Function GetRandString(lenth)
Dim rndstr,i
Randomize
rndstr = ""
i = 1
do while i <= lenth
rndstr = rndstr & Chr(cint(((120 - 98 + 1) * Rnd )+ 97))
i = i + 1
loop
GetRandString = rndstr
End Function
Function CreateDbConn()
Dim DbConn,ConnKey
Set DbConn = Server.CreateObject("ADODB.Connection")
DbConn.Open Connstr
ConnKey = GetRandString(10)
DbPool.Add ConnKey,DbConn
End Function
Function GetDbConn()
Dim CurKey,Keys
If DbPool.Count > 0 Then
Keys = DbPool.Keys ' 獲取鍵名。
CurKey = Keys(0)
Response.Write "Cur DbConn Key Is : " & CurKey & "<br />"
Set Conn = Server.CreateObject("ADODB.Connection")
Set Conn = DbPool(CurKey)
If Conn.State = adStateClosed Then '如果這個(gè)連接已經(jīng)關(guān)閉，將其從池里注銷，再新建一個(gè)可用的連接并添加到池里
DbPool.Remove CurKey
Call CreateDbConn() '新建一個(gè)連接并添加到池里
Set GetDbConn = GetDbConn()
Else '否則的話，將其從池里注銷，然后將復(fù)制的對(duì)象返回
DbPool.Remove CurKey
Set GetDbConn = Conn
Exit Function
End If
Else
Response.Write "連接池已用完，請(qǐng)重新初始化應(yīng)用程序"
Response.End
End if
End Function
Function FreeDbConn(DbConn)
DbPool.Add GetRandString(10),DbConn
End Function
2.全局文件 global.asa
<object ID="DbPool" Progid="Scripting.Dictionary" Scope="Application" runat="server"></object> <!--#include file="DbPool.asp"--> < % Sub Application_OnStart Dim ConnKey For i = 1 To PoolSize '建立指定數(shù)目的數(shù)據(jù)庫(kù)連接 CreateDbConn() Next End Sub Sub Application_OnEnd DbPool.RemoveAll End Sub %>
3.測(cè)試文件 test.asp
<!--#include file="DbPool.asp"-->
< %
Response.Write "Test Start:<br>"
Response.Write "Current Objects count : " & DbPool.Count & "<br />"
Set dbconn = Server.CreateObject("ADODB.Connection")
Set dbconn = GetDbConn()
Response.Write "get one connection from pool <br />"
Response.Write "Current Objects count : " & DbPool.Count & "<br />"
Set Rs = Server.CreateObject("ADODB.Recordset")
Rs.open "select * from mkdb",dbconn,1,1
Do While Not rs.eof
Response.write Rs("v_oid") & "<br />"
Rs.movenext
loop
FreeDbConn(dbconn)
Response.Write "free one connection to pool <br />"
Response.Write "Current Objects count : " & DbPool.Count & "<br />"
%>
