学步园

    有时候，我们需要把一个类对象序列化成字符串保存起来，或者通过网络传输给另一台机器，然后再异步或异地克隆出原来的类对象，比如ACCESS没有服务器端，而我们加它加了一个服务器代理程序，代理程序负责把查询出来的记录集传输给客户端，这时，我们可以遍历记录集内容，生成一个字符串传输给客户端，然后在客户端再加载记录集内容。其实，利用VB内置的类对象PropertyBag，我们还可以直接序列化记录集对象，传输给客户端后，客户端直接复制出该对象就可行，比遍历记录集的效率提高了N倍。

    序列化的代码如下：

Option Explicit</p> <p>'* ************************************** *<br /> '* 模块名称：modStream.bas<br /> '* 模块功能：序列化类对象为字符串<br /> '* 作者：lyserver<br /> '* ************************************** *</p> <p>'- -----------------------------------<br /> ' 函数说明：将类对象序列化为字符串<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 /> ' 函数说明：从字符串中加载类对象<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 />

    测试代码如下：

'测试代码如下：<br /> Sub Main()<br /> Dim rstTemp As Object<br /> Dim strStream As String</p> <p> '创建一个临时ADO记录集对象<br /> Set rstTemp = CreateObject("ADODB.Recordset")<br /> rstTemp.Fields.Append "姓名", adBSTR, 4 '设置临时记录集字段<br /> rstTemp.Fields.Append "性别", adBSTR, 1<br /> rstTemp.Open '打开记录集<br /> rstTemp.AddNew Array("姓名", "性别"), Array("张三", "男") '添加记录</p> <p> '将记录集对象序列化为字符串<br /> strStream = ObjectSaveToString(rstTemp, "rstTemp")</p> <p> '关闭并销毁ADO记录集对象<br /> rstTemp.Close<br /> Set rstTemp = Nothing</p> <p> '从字符串中加载记录集对象<br /> Set rstTemp = ObjectLoadFromString(strStream, "rstTemp")<br /> Debug.Print rstTemp.Fields(0).Value '显示结果</p> <p> '关闭并销毁ADO记录集对象<br /> rstTemp.Close<br /> Set rstTemp = Nothing<br /> End Sub<br />