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将SAX加入我们的ASP应用中
2009/11/8 13:19:18
    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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