避免XML selectSingleNode函数的异常

Try
    Dim node As XmlNode = xmlDoc.SelectSingleNode("/root/node")
    ' 处理节点
Catch ex As Exception
    ' 处理异常
End Try

Dim nodes As XmlNodeList = xmlDoc.SelectNodes("/root/node")
If nodes.Count > 0 Then
    Dim node As XmlNode = nodes(0)
    ' 处理节点
End If

Dim nodeExists As Boolean = xmlDoc.SelectSingleNode("/root/node") IsNot Nothing
If nodeExists Then
    Dim node As XmlNode = xmlDoc.SelectSingleNode("/root/node")
    ' 处理节点
End If