數(shù)據(jù)庫連接是一種關(guān)鍵的有限的昂貴的資源，這一點(diǎn)在多用戶的網(wǎng)頁應(yīng)用程序中體現(xiàn)得尤為突出。對數(shù)據(jù)庫連接的管理能顯著影響到整個應(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)庫連接池正是針對這個問題提出來的。數(shù)據(jù)庫連接池負(fù)責(zé)分配、管理和釋放數(shù)據(jù)庫連接，它允許應(yīng)用程序重復(fù)使用一個現(xiàn)有的數(shù)據(jù)庫連接，而再不是重新建立一個；釋放空閑時間超過最大空閑時間的數(shù)據(jù)庫連接來避免因?yàn)闆]有釋放數(shù)據(jù)庫連接而引起的數(shù)據(jù)庫連接遺漏。這項技術(shù)能明顯提高對數(shù)據(jù)庫操作的性能。
但是這項技術(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，下面就是研究出來的asp版本，能夠加快網(wǎng)頁的訪問速度，降低數(shù)據(jù)庫的壓力。
1.數(shù)據(jù)庫連接文件 DbPool.asp
< %Const PoolSize = 10Const Connstr = "Driver={SQL Server};Server=(local);UID=sa;word=555;Database=db" Function GetRandString(lenth)Dim rndstr,iRandomizerndstr = ""i = 1do while i <= lenthrndstr = rndstr & Chr(cint(((120 - 98 + 1) * Rnd )+ 97))i = i + 1loopGetRandString = rndstrEnd Function Function CreateDbConn()Dim DbConn,ConnKeySet DbConn = Server.CreateObject("ADODB.Connection")DbConn.Open ConnstrConnKey = GetRandString(10)DbPool.Add ConnKey,DbConnEnd Function Function GetDbConn()Dim CurKey,KeysIf DbPool.Count > 0 ThenKeys = 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 '如果這個連接已經(jīng)關(guān)閉，將其從池里注銷，再新建一個可用的連接并添加到池里DbPool.Remove CurKeyCall CreateDbConn() '新建一個連接并添加到池里Set GetDbConn = GetDbConn()Else '否則的話，將其從池里注銷，然后將復(fù)制的對象返回DbPool.Remove CurKeySet GetDbConn = ConnExit FunctionEnd IfElseResponse.Write "連接池已用完，請重新初始化應(yīng)用程序"Response.EndEnd ifEnd Function Function FreeDbConn(DbConn)DbPool.Add GetRandString(10),DbConnEnd 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_OnStartDim ConnKeyFor i = 1 To PoolSize '建立指定數(shù)目的數(shù)據(jù)庫連接CreateDbConn()NextEnd Sub Sub Application_OnEndDbPool.RemoveAllEnd Sub%>
3.測試文件 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,1,1Do While Not rs.eofResponse.write Rs("v_oid") & "<br />"Rs.movenextloop FreeDbConn(dbconn)Response.Write "free one connection to pool <br />"Response.Write "Current Objects count : " & DbPool.Count & "<br />" %>
