将SAX加入我们的ASP应用中

答案：在处理大型的XML文档的时候，在服务器端直接使用XML DOM的时候速度是比较慢的，当我第一次接触到SAX的时候，我意识到我们应该在服务器端将DOM和SAX结合起来以提高我们程序的效率。我们在ASP中最常使用的就是使用COM来完成这个工作（也许你有更好的方法）。

废话少说，还是直接进入实际的代码部分了（下面只是包含了最基本的代码而已）。

首先我们创建一个DLL来封装SAX的功能好了。
测试环境：Win2k Prof.+MSXML3.0 sp1+VB6
要使用SAX我们必须引用（Reference）Microsoft XML 3.0（我的机器安装的是MSXML3.0 sp1）

工程名：SAXTesting

类名：clsSAXTest
方法：Public Function MyXMLParser(XML文件物理路径) as DOMDocument
代码：
Option Explicit


Public Function MyXMLParser(ByVal strXMLFilePath As Variant) As DOMDocument
    Dim reader As New SAXXMLReader
    Dim contentHandler As New ContentHandlerImpl
    Dim errorHandler As New ErrorHandlerImpl
    
    
    Set reader.contentHandler = contentHandler
    Set reader.errorHandler = errorHandler
    On Error GoTo ErrorHandle
    Dim XMLFile As String
    XMLFile = strXMLFilePath
    reader.parseURL (XMLFile)
    
    Dim xmlDoc As MSXML2.DOMDocument
    Set xmlDoc = CreateObject("MSXML2.DOMDocument")
    xmlDoc.loadXML strXML
    Set MyXMLParser = xmlDoc
    Set xmlDoc = Nothing
    Exit Function
    
ErrorHandle:
    Err.Raise 9999, "My XML Parser", Err.Number & " : " & Err.Description

End Function

类名:modPublic
代码：
Option Explicit

Global strXML As String

类名：ContentHandlerImpl
代码：
Option Explicit

Implements IVBSAXContentHandler


Private Sub IVBSAXContentHandler_startElement(strNamespaceURI As String, strLocalName As String, 

strQName As String, ByVal attributes As MSXML2.IVBSAXAttributes)
    
    Dim i As Integer
    
    intLocker = intLocker + 1
    If intLocker > 1 Then
        
    End If
    strXML = strXML & "<" & strLocalName
   
    For i = 0 To (attributes.length - 1)
        strXML = strXML & " " & attributes.getLocalName(i) & "=""" & attributes.getValue(i) & 

""""
    Next

    strXML = strXML & ">"
    
    If strLocalName = "qu" Then
        Err.Raise vbObjectError + 1, "ContentHandler.startElement", "Found element <qu>"
    End If

End Sub

Private Sub IVBSAXContentHandler_endElement(strNamespaceURI As String, strLocalName As String, 

strQName As String)
    
    strXML = strXML & "</" & strLocalName & ">"
    
End Sub

Private Sub IVBSAXContentHandler_characters(text As String)
    text = Replace(text, vbLf, vbCrLf)
    strXML = strXML & text
    
End Sub

Private Property Set IVBSAXContentHandler_documentLocator(ByVal RHS As MSXML2.IVBSAXLocator)

End Property

Private Sub IVBSAXContentHandler_endDocument()

End Sub

Private Sub IVBSAXContentHandler_endPrefixMapping(strPrefix As String)

End Sub

Private Sub IVBSAXContentHandler_ignorableWhitespace(strChars As String)

End Sub

Private Sub IVBSAXContentHandler_processingInstruction(target As String, data As String)
    
    strXML = strXML & "<?" & target & " " & data & ">"

End Sub

Private Sub IVBSAXContentHandler_skippedEntity(strName As String)

End Sub

Private Sub IVBSAXContentHandler_startDocument()

End Sub

Private Sub IVBSAXContentHandler_startPrefixMapping(strPrefix As String, strURI As String)

End Sub


类名：ErrorHandlerImpl
代码：
Option Explicit

Implements IVBSAXErrorHandler


Private Sub IVBSAXErrorHandler_fatalError(ByVal lctr As IVBSAXLocator, msg As String, ByVal 

errCode As Long)
        
        strXML = strXML & "*** error *** " & msg
    
End Sub

Private Sub IVBSAXErrorHandler_error(ByVal lctr As IVBSAXLocator, msg As String, ByVal errCode As 

Long)
    
End Sub

Private Sub IVBSAXErrorHandler_ignorableWarning(ByVal oLocator As MSXML2.IVBSAXLocator, 

strErrorMessage As String, ByVal nErrorCode As Long)

End Sub


OK，让我们编译这个DLL，应该是没什么问题了。让我们在ASP中看看运行的结果怎么样：
XML文件：
<?xml version="1.0"?>
<root foo="bar.com">
<PARTS>
   <PART foo="bar.com"  foo2="bar.com">
 <PARTNO>12345</PARTNO>
 <DESCRIPTION>VIP - Very Important Part</DESCRIPTION>
   </PART>
   <PART>
 <PARTNO>5678</PARTNO>
 <DESCRIPTION>LIP - Less Important Part</DESCRIPTION>
   </PART>
</PARTS>
</root>

ASP文件：
<%
Set a = CreateObject("SAXTesting.clsSAXTest")
Set xmlDoc = a.MyXMLParser("D:\test.xml")
Response.contenttype="text/xml"
response.write xmlDoc.xml
set xmlDoc=nothing
set a=nothing
%>

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