Using XMLTextReader to Read XML Data
The XMLTextReader can be much easier than the DOM or SAX to locate and filter data. It is ideal for large files since unlike the DOM it never loads an entire file in memory. Its design is so you can read through the file and when you notice items you want to grab you respond appropriately.
Here is code to read any XML File with an XMLTextReader object and see what types it emits. This toy program displays all the emitted types in a table for ANY XML FILE in this case the sample file @ http://www.learnasp.com/experiments/data/favebooks.xml, but you can easily run this on any XML file to know exactly what types an XMLTextReader will emit.
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<%@trace="false" debug="true" %>
<%@ Import Namespace="System.XML"%>
<%@ Import Namespace="system.xml.xmlnodetype"%>
<%@ Import Namespace="system.drawing"%>
<script language="VB" runat="server">
Sub Page_Load(S As Object, E As EventArgs)
trace.tracemode=TraceMode.SortByTime
DIM Xmltr1 as XMLTextReader
TRY
Xmltr1=new XMLtextReader(server.mappath("/experiments/data/favebooks.xml"))
DIM strTemp as string
DO WHILE Xmltr1.Read()
trace.warn ("Value", Xmltr1.Value)
'trace.write ("Text", Xmltr1.Text)
strTemp = "NodeType=" & Xmltr1.NodeType.ToString()
IF Xmltr1.Name<>string.empty
strTemp &= ";Name=" & Xmltr1.Name
END IF
IF Xmltr1.LocalName<>string.empty
strTemp &= ";LocalName=" & Xmltr1.LocalName
END IF
IF Xmltr1.NamespaceURI<>string.empty
strTemp &= ";NamespaceURI=" & Xmltr1.NamespaceURI
END IF
trace.write("",strTemp)
TableCellsAdd(XMLtr1.Value,strTemp)
IF Xmltr1.hasattributes
trace.write ("attributecount", Xmltr1.attributecount)
DO WHILE Xmltr1.MoveTonextAttribute()
trace.write ("value;name",Xmltr1.name & ";" & Xmltr1.value)
TableCellsAdd("attribute named <b>" & XMLtr1.Name & "</b>;value=<font color='red'>" & XMLtr1.Value & "</font>","")
LOOP
END IF
LOOP
CATCH ex1 as exception
FINALLY
Xmltr1.Close()
END TRY
End Sub
Sub TableCellsAdd(strParm1 as string,strParm2 as string)
static intCellcounter as integer
DIM cl1,cl2 as tablecell
DIM rw1 as tablerow
cl1=new tablecell
cl2=new tablecell
cl1.controls.add(new literalcontrol(strParm1))
cl2.controls.add(new literalcontrol(strParm2))
rw1=new tablerow
rw1.cells.add(cl1)
rw1.cells.add(cl2)
intCellCounter+=1
IF intCellCounter MOD 2 = 0
rw1.BackColor=Color.FromName("Silver")
END IF
tblXMLDetails.rows.add(rw1)
End Sub
</script>
<html><head>
<title>XML Demo</title>
</head>
<body bgcolor="#FFFFFF">
<form runat="server">
<ASP:placeholder id="plcErr" runat="server" />
See The Trace For More Details
<AsP:Table id="tblXMlDetails" runat="server" />
<ASP:placeholder id="plcEndofPage" runat="server" />
</form>
</body></html> |
Visit http://www.learnasp.com for more Charles Carroll ASP related tutorials.
Emir Plicanic owns and operates a web design company, is a graphic designer at a nation wide company, and enjoys teaching Dreamweaver to enthusiastic students at a local college.
