NotesSAXParser 全攻略 — LotusScript 串流式 XML 解析、12 個 SAX 事件、On Event 綁定模式

讀到 <book>     → 觸發 SAX_StartElement("book", attrs)
讀到 "harry"    → 觸發 SAX_Characters("harry")
讀到 </book>    → 觸發 SAX_EndElement("book")

Dim session As New NotesSession
Dim saxParser As NotesSAXParser
Dim xml_in As NotesStream
Dim xml_out As NotesStream

Set xml_in = session.CreateStream
Call xml_in.Open("c:\data\input.xml")

Set xml_out = session.CreateStream
Call xml_out.Open("c:\data\output.txt")
Call xml_out.Truncate

Set saxParser = session.CreateSAXParser(xml_in, xml_out)

On Event SAX_StartElement From saxParser Call MyStartElementHandler
On Event SAX_EndElement   From saxParser Call MyEndElementHandler
On Event SAX_Characters   From saxParser Call MyCharactersHandler
On Event SAX_FatalError   From saxParser Call MyFatalErrorHandler

Sub MyStartElementHandler(Source As NotesSAXParser, Namespace As String, _
    LocalName As String, QName As String, Attributes As NotesSAXAttributeList)
    Print "Start: " & QName
    ' 用 Attributes 物件拿屬性
End Sub

Sub MyCharactersHandler(Source As NotesSAXParser, Chars As String, Start As Long, Length As Long)
    Print "Text chunk: " & Mid(Chars, Start + 1, Length)
End Sub

Option Public

Dim currentElement As String   ' 全域 — handler 之間共用狀態
Dim currentBook As String
Dim currentTitle As String

Sub Initialize
    Dim session As New NotesSession
    Dim saxParser As NotesSAXParser
    Dim xml_in As NotesStream

    Set xml_in = session.CreateStream
    If Not xml_in.Open("c:\data\books.xml") Then
        Print "Cannot open input"
        Exit Sub
    End If

    Set saxParser = session.CreateSAXParser(xml_in, Nothing)

    ' 綁四個 handler
    On Event SAX_StartElement From saxParser Call OnStartElement
    On Event SAX_EndElement   From saxParser Call OnEndElement
    On Event SAX_Characters   From saxParser Call OnCharacters
    On Event SAX_FatalError   From saxParser Call OnFatalError

    Call saxParser.Parse()

    Print "Done"
End Sub

Sub OnStartElement(Source As NotesSAXParser, Namespace As String, _
        LocalName As String, QName As String, Attributes As NotesSAXAttributeList)
    currentElement = LocalName
    currentTitle = ""             ' 進入新 element 清空 buffer

    If LocalName = "book" Then
        currentBook = ""
        ' 從 Attributes 拿 id 屬性
        Dim i As Integer
        For i = 0 To Attributes.Length - 1
            If Attributes.GetLocalName(i) = "id" Then
                Print "Book id = " & Attributes.GetValue(i)
            End If
        Next i
    End If
End Sub

Sub OnCharacters(Source As NotesSAXParser, Chars As String, _
        Start As Long, Length As Long)
    ' Characters 對同一段文字可能多次觸發 — 累加
    If currentElement = "title" Then
        currentTitle = currentTitle & Mid(Chars, Start + 1, Length)
    End If
End Sub

Sub OnEndElement(Source As NotesSAXParser, Namespace As String, _
        LocalName As String, QName As String)
    If LocalName = "title" Then
        Print "  Title: " & currentTitle
    End If
End Sub

Sub OnFatalError(Source As NotesSAXParser, Description As String, _
        SystemId As String, PublicId As String, LineNumber As Long, ColumnNumber As Long)
    Print "FATAL at line " & LineNumber & ": " & Description
End Sub

<title>The Lord of the Rings</title>

Sub OnStartElement(...)
    currentText = ""
End Sub

Sub OnCharacters(Source, Chars, Start, Length)
    currentText = currentText & Mid(Chars, Start + 1, Length)
End Sub

Sub OnEndElement(...)
    Print currentText  ' 完整字串
End Sub

On Event SAX_Error      From saxParser Call OnError
On Event SAX_Warning    From saxParser Call OnWarning
On Event SAX_FatalError From saxParser Call OnFatalError

Dim i As Integer
For i = 0 To Attributes.Length - 1
    Print Attributes.GetLocalName(i) & " = " & Attributes.GetValue(i)
Next i