'Visual Basic.NET How to Program, Second Edition
'by Harvey M. Deitel (Author), Paul J. Deitel (Author), Tem R. Nieto (Author)
' Publisher: Prentice Hall; 2 edition (December 11, 2001)
' Language: English
' ISBN-10: 0130293636
' ISBN-13: 978-0130293633
Imports System.Windows.Forms
Imports System.Xml.XPath
public class FrmPathNavigatorDemo
public Shared Sub Main
Application.Run(New FrmPathNavigator)
End Sub
End class
Public Class FrmPathNavigator
Inherits Form
' GroupBox contains Controls for locating XML file
Friend WithEvents locateGroupBox As GroupBox
Friend WithEvents cmdSelect As Button
Friend WithEvents cboSelect As ComboBox
Friend WithEvents txtSelect As TextBox
' GroupBox contains Controls for navigating DOM tree
Friend WithEvents navigateGroupBox As GroupBox
Friend WithEvents cmdNext As Button
Friend WithEvents cmdPrevious As Button
Friend WithEvents cmdParent As Button
Friend WithEvents cmdFirstChild As Button
' TreeView displays DOM-tree results
Friend WithEvents trePath As TreeView
' navigator to traverse document
Private xPath As XPathNavigator
' references document for use by XPathNavigator
Private document As XPathDocument
' references TreeNode list used by TreeView control
Private tree As TreeNode
Public Sub New()
MyBase.New()
' This call is required by the Windows Form Designer.
InitializeComponent()
' Add any initialization after the
' InitializeComponent() call
' load in XML document
document = New XPathDocument("YourFile.xml")
' create nagivator
xPath = document.CreateNavigator
' create root node for TreeNodes
tree = New TreeNode()
tree.Text = xPath.NodeType.ToString ' #root
trePath.Nodes.Add(tree) ' add tree
' update TreeView control
trePath.ExpandAll()
trePath.Refresh()
trePath.SelectedNode = tree ' highlight root
End Sub ' New
#Region " Windows Form Designer generated code "
'Form overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub
'Required by the Windows Form Designer
Private components As System.ComponentModel.Container
'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
Me.cboSelect = New System.Windows.Forms.ComboBox()
Me.trePath = New System.Windows.Forms.TreeView()
Me.navigateGroupBox = New System.Windows.Forms.GroupBox()
Me.cmdFirstChild = New System.Windows.Forms.Button()
Me.cmdParent = New System.Windows.Forms.Button()
Me.cmdNext = New System.Windows.Forms.Button()
Me.cmdPrevious = New System.Windows.Forms.Button()
Me.txtSelect = New System.Windows.Forms.TextBox()
Me.locateGroupBox = New System.Windows.Forms.GroupBox()
Me.cmdSelect = New System.Windows.Forms.Button()
Me.navigateGroupBox.SuspendLayout()
Me.locateGroupBox.SuspendLayout()
Me.SuspendLayout()
'
'cboSelect
'
Me.cboSelect.DropDownWidth = 121
Me.cboSelect.Items.AddRange(New Object() {"/sports", "/sports/game/name", "/sports/game/paragraph", "/sports/game [name='Cricket']"})
Me.cboSelect.Location = New System.Drawing.Point(104, 32)
Me.cboSelect.Name = "cboSelect"
Me.cboSelect.Size = New System.Drawing.Size(224, 24)
Me.cboSelect.TabIndex = 1
'
'trePath
'
Me.trePath.FullRowSelect = True
Me.trePath.HideSelection = False
Me.trePath.ImageIndex = -1
Me.trePath.Location = New System.Drawing.Point(8, 272)
Me.trePath.Name = "trePath"
Me.trePath.SelectedImageIndex = -1
Me.trePath.Size = New System.Drawing.Size(336, 136)
Me.trePath.TabIndex = 2
'
'navigateGroupBox
'
Me.navigateGroupBox.Controls.AddRange(New System.Windows.Forms.Control() {Me.cmdFirstChild, Me.cmdParent, Me.cmdNext, Me.cmdPrevious})
Me.navigateGroupBox.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
Me.navigateGroupBox.Location = New System.Drawing.Point(84, 144)
Me.navigateGroupBox.Name = "navigateGroupBox"
Me.navigateGroupBox.Size = New System.Drawing.Size(184, 120)
Me.navigateGroupBox.TabIndex = 1
Me.navigateGroupBox.TabStop = False
Me.navigateGroupBox.Text = "Navigation Controls"
'
'cmdFirstChild
'
Me.cmdFirstChild.Location = New System.Drawing.Point(104, 56)
Me.cmdFirstChild.Name = "cmdFirstChild"
Me.cmdFirstChild.TabIndex = 5
Me.cmdFirstChild.Text = "First Child"
'
'cmdParent
'
Me.cmdParent.Location = New System.Drawing.Point(8, 56)
Me.cmdParent.Name = "cmdParent"
Me.cmdParent.TabIndex = 4
Me.cmdParent.Text = "Parent"
'
'cmdNext
'
Me.cmdNext.Location = New System.Drawing.Point(56, 88)
Me.cmdNext.Name = "cmdNext"
Me.cmdNext.TabIndex = 3
Me.cmdNext.Text = "Next"
'
'cmdPrevious
'
Me.cmdPrevious.Location = New System.Drawing.Point(56, 24)
Me.cmdPrevious.Name = "cmdPrevious"
Me.cmdPrevious.TabIndex = 2
Me.cmdPrevious.Text = "Previous"
'
'txtSelect
'
Me.txtSelect.BackColor = System.Drawing.SystemColors.Info
Me.txtSelect.Location = New System.Drawing.Point(8, 64)
Me.txtSelect.Multiline = True
Me.txtSelect.Name = "txtSelect"
Me.txtSelect.ReadOnly = True
Me.txtSelect.Size = New System.Drawing.Size(320, 56)
Me.txtSelect.TabIndex = 2
Me.txtSelect.Text = ""
'
'locateGroupBox
'
Me.locateGroupBox.Controls.AddRange(New System.Windows.Forms.Control() {Me.txtSelect, Me.cmdSelect, Me.cboSelect})
Me.locateGroupBox.Font = New System.Drawing.Font("Microsoft Sans Serif", 9.75!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
Me.locateGroupBox.Location = New System.Drawing.Point(8, 8)
Me.locateGroupBox.Name = "locateGroupBox"
Me.locateGroupBox.Size = New System.Drawing.Size(336, 128)
Me.locateGroupBox.TabIndex = 0
Me.locateGroupBox.TabStop = False
Me.locateGroupBox.Text = "Locate Element"
'
'cmdSelect
'
Me.cmdSelect.Location = New System.Drawing.Point(8, 32)
Me.cmdSelect.Name = "cmdSelect"
Me.cmdSelect.TabIndex = 1
Me.cmdSelect.Text = "Select"
'
'FrmPathNavigator
'
Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
Me.ClientSize = New System.Drawing.Size(352, 413)
Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.trePath, Me.navigateGroupBox, Me.locateGroupBox})
Me.Name = "FrmPathNavigator"
Me.Text = "Path Navigator"
Me.navigateGroupBox.ResumeLayout(False)
Me.locateGroupBox.ResumeLayout(False)
Me.ResumeLayout(False)
End Sub
#End Region
' traverse to first child
Private Sub cmdFirstChild_Click( _
ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles cmdFirstChild.Click
Dim newTreeNode As TreeNode
If xPath.MoveToFirstChild Then
newTreeNode = New TreeNode() ' create new node
DetermineType(newTreeNode, xPath)
tree.Nodes.Add(newTreeNode)
tree = newTreeNode ' assign tree newTreeNode
trePath.ExpandAll()
trePath.Refresh()
trePath.SelectedNode = tree
Else
Console.WriteLine("Current Node has no children.")
End If
End Sub ' cmdFirstChild_Click
Private Sub cmdParent_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles cmdParent.Click
If xPath.MoveToParent Then
tree = tree.Parent
Dim count As Integer = tree.GetNodeCount(False)
Dim i As Integer
For i = 0 To count - 1
tree.Nodes.Remove(tree.FirstNode)
Next
trePath.ExpandAll()
trePath.Refresh()
trePath.SelectedNode = tree
Else
Console.WriteLine("Current node has no parent.", "", _
MessageBoxButtons.OK, MessageBoxIcon.Information)
End If
End Sub ' cmdParent_Click
Private Sub cmdNext_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles cmdNext.Click
Dim newTreeNode As TreeNode = Nothing
Dim newNode As TreeNode = Nothing
If xPath.MoveToNext Then
newTreeNode = tree.Parent ' get parent node
newNode = New TreeNode() ' create new node
DetermineType(newNode, xPath)
newTreeNode.Nodes.Add(newNode)
tree = newNode
trePath.ExpandAll()
trePath.Refresh()
trePath.SelectedNode = tree
Else
Console.WriteLine("Current node is last sibling.", "", _
MessageBoxButtons.OK, MessageBoxIcon.Information)
End If
End Sub
Private Sub cmdPrevious_Click( _
ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles cmdPrevious.Click
Dim parentTreeNode As TreeNode = Nothing
If xPath.MoveToPrevious Then
parentTreeNode = tree.Parent ' get parent node
' delete current node
parentTreeNode.Nodes.Remove(tree)
' move to previous node
tree = parentTreeNode.LastNode
' update TreeView control
trePath.ExpandAll()
trePath.Refresh()
trePath.SelectedNode = tree
Else ' if current node has no previous siblings
MessageBox.Show("Current node is first sibling.", "", _
MessageBoxButtons.OK, MessageBoxIcon.Information)
End If
End Sub ' cmdPrevious_Click
' process cmdSelect_Click event
Private Sub cmdSelect_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles cmdSelect.Click
Dim iterator As XPathNodeIterator ' enables node iteration
' get specified node from ComboBox
Try
iterator = xPath.Select(cboSelect.Text)
DisplayIterator(iterator) ' print selection
' catch invalid expressions
Catch argumentException As System.ArgumentException
MessageBox.Show(argumentException.Message, "Error", _
MessageBoxButtons.OK, MessageBoxIcon.Error)
End Try
End Sub ' cmdSelect_Click
' print values for XPathNodeIterator
Private Sub DisplayIterator( _
ByVal iterator As XPathNodeIterator)
txtSelect.Clear()
' prints selected node's values
While iterator.MoveNext
txtSelect.Text &= iterator.Current.Value.Trim & vbCrLf
End While
End Sub ' DisplayIterator
' determine if TreeNode should display current node
' name or value
Private Sub DetermineType(ByVal node As TreeNode, _
ByVal xPath As XPathNavigator)
' determine NodeType
Select Case xPath.NodeType
Case XPathNodeType.Element ' if Element, get its name
' get current node name, and remove whitespaces
node.Text = xPath.Name.Trim
Case Else ' obtain node values
' get current node value and remove whitespaces
node.Text = xPath.Value.Trim
End Select
End Sub
End Class
' *************************************************************
' * (C) Copyright 2002 by Deitel & Associates, Inc. *
' * and Prentice Hall. *
' * All Rights Reserved. *
' * *
' * DISCLAIMER: The authors and publisher of this book have *
' * used their best efforts in preparing the book. These *
' * efforts include the development, research, and testing of *
' * the theories and programs to determine their *
' * effectiveness. The authors and publisher make no warranty *
' * of any kind, expressed or implied, with regard to these *
' * programs or to the documentation contained in these books.*
' * The authors and publisher shall not be liable in any event*
' * for incidental or consequential damages in connection *
' * with, or arising out of, the furnishing, performance, or *
' * use of these programs. *
' *************************************************************