在VB中將類對象序列化為字串

    有時候，我們需要把一個類對象序列化成字串儲存起來，或者通過網路傳輸給另一台機器，然後再非同步或異地複製出原來的類對象，比如ACCESS沒有伺服器端，而我們加它加了一個伺服器代理程式，代理程式負責把查詢出來的記錄集傳輸給用戶端，這時，我們可以遍曆記錄集內容，產生一個字串傳輸給用戶端，然後在用戶端再載入記錄集內容。其實，利用VB內建的類對象PropertyBag，我們還可以直接序列化記錄集對象，傳輸給用戶端後，用戶端直接複製出該對象就可行，比遍曆記錄集的效率提高了N倍。

    序列化的代碼如下：

Option Explicit</p><p>'* ************************************** *<br />'* 模組名稱：modStream.bas<br />'* 模組功能：序列化類別對象為字串<br />'* 作者：lyserver<br />'* ************************************** *</p><p>'- -----------------------------------<br />' 函數說明：將類對象序列化為字串<br />'- -----------------------------------<br />Function ObjectSaveToString(objSource As Object, KeyName As String) As String<br /> Dim i As Long<br /> Dim objBag As New PropertyBag<br /> Dim bytData() As Byte</p><p> On Error Resume Next<br /> If objSource Is Nothing Or Len(KeyName) = 0 Then Exit Function</p><p> objBag.WriteProperty KeyName, objSource<br /> bytData = objBag.Contents<br /> For i = 0 To UBound(bytData)<br /> ObjectSaveToString = ObjectSaveToString & IIf(bytData(i) < 16, "0", "") & Hex(bytData(i))<br /> Next<br />End Function</p><p>'- -----------------------------------<br />' 函數說明：從字串中載入類對象<br />'- -----------------------------------<br />Function ObjectLoadFromString(strSource As String, KeyName As String) As Object<br /> Dim i As Long, nLen As Long<br /> Dim objBag As New PropertyBag<br /> Dim bytData() As Byte</p><p> On Error Resume Next<br /> nLen = Len(strSource)<br /> If nLen = 0 Or Len(KeyName) = 0 Then Exit Function</p><p> ReDim bytData(nLen / 2 - 1)<br /> For i = 0 To UBound(bytData)<br /> bytData(i) = Val("&H" & Mid(strSource, i * 2 + 1, 2))<br /> Next<br /> objBag.Contents = bytData<br /> Set ObjectLoadFromString = objBag.ReadProperty(KeyName)<br />End Function<br />

    測試代碼如下：

'測試代碼如下：<br />Sub Main()<br /> Dim rstTemp As Object<br /> Dim strStream As String</p><p> '建立一個臨時ADO記錄集對象<br /> Set rstTemp = CreateObject("ADODB.Recordset")<br /> rstTemp.Fields.Append "姓名", adBSTR, 4 '設定臨時記錄集欄位<br /> rstTemp.Fields.Append "性別", adBSTR, 1<br /> rstTemp.Open '開啟記錄集<br /> rstTemp.AddNew Array("姓名", "性別"), Array("張三", "男") '添加記錄</p><p> '將記錄集對象序列化為字串<br /> strStream = ObjectSaveToString(rstTemp, "rstTemp")</p><p> '關閉並銷毀ADO記錄集對象<br /> rstTemp.Close<br /> Set rstTemp = Nothing</p><p> '從字串中載入記錄集對象<br /> Set rstTemp = ObjectLoadFromString(strStream, "rstTemp")<br /> Debug.Print rstTemp.Fields(0).Value '顯示結果</p><p> '關閉並銷毀ADO記錄集對象<br /> rstTemp.Close<br /> Set rstTemp = Nothing<br />End Sub<br />