vb.net 教程 4-10 XML文件操作 4-2

主窗体的代码：

需要引用的类：

Imports System.Threading
Imports System.Xml
Imports System.IO
Imports System.Net

窗体级变量：

Dim xmlfile As String	'保存地址的xml文件
Dim pingTime As Integer     'ping超时时间，毫秒，默认为500
Dim threadCheck As Thread   '检测线程
Dim blStopCheck As Boolean  '是否停止检测标记

窗体载入时，载入xml文件中的数据，并显示在ListView控件：

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Me.CheckForIllegalCrossThreadCalls = False   ‘设置允许窗体和多线程交互

xmlfile = Application.StartupPath.TrimEnd("\") & "\linked.dat"
pingTime = 500             ’设置Ping超时时间

Call localInfo()

'载入xml中的数据
If loadXmlData() = False Then
Exit Sub
End If
btnStart.Enabled = True
btnDel.Enabled = True

comTime.Text = comTime.Items(2).ToString
End Sub

获取当前网络状态等信息，并显示到状态栏中：

Private Sub localInfo()
Dim info As String = ""
If My.Computer.Network.IsAvailable Then
info = "网络连接中"
Dim localname As String
localname = System.Net.Dns.GetHostName
Dim localips() As IPAddress
localips = System.Net.Dns.GetHostByName(localname).AddressList
Dim localip As String
If localips.Length > 0 Then
localip = localips(0).ToString
Else
localip = ""
End If
info &= "，IP地址：" & localip
Else
info = "网络不可用"
End If

Dim strAuthor As String = "程序设计：http://blog.csdn.net/uruseibest"
info = strAuthor & "     " & info
tsslInfo.Text = info
End Sub

载入XML中的数据并在ListView中显示：

Private Function loadXmlData() As Boolean

'文件不存在
If File.Exists(xmlfile) = False Then
'创建文件
Call createDatafile()
End If
Dim xd As New XmlDocument()
Try
xd.Load(xmlfile)
Dim addrNodes As XmlNodeList
addrNodes = xd.SelectNodes("//addrdata/addrlist")
Dim i As Integer = 0
Dim addrname As String = ""
Dim addrinfo As String = ""
Dim addrtype As String = ""
If addrNodes.Count > 0 Then
For Each addrNode As XmlNode In addrNodes
i += 1
Dim addrNodeInfos As XmlNodeList
addrNodeInfos = addrNode.ChildNodes

addrname = addrNodeInfos(0).InnerText
addrinfo = addrNodeInfos(1).InnerText
addrtype = addrNodeInfos(2).InnerText

Dim lvAddrInfo As New ListViewItem()
lvAddrInfo.Text = i
lvAddrInfo.SubItems.Add(addrname)
lvAddrInfo.SubItems.Add(addrtype)
lvAddrInfo.SubItems.Add(addrinfo)
lvAddrInfo.SubItems.Add("等待")
lvAddrInfo.SubItems.Add("")
lvCheck.Items.Add(lvAddrInfo)

Next
End If

Catch ex As Exception
Return False
End Try
Return True
End Function

注意，当xml文件不存在的时候，创建一个没有数据的xml文件：

Private Sub createDatafile()
Dim strXmlDefault() As String
ReDim strXmlDefault(2)
strXmlDefault(0) = "<?xml version=""1.0"" encoding=""utf-8""?>"
strXmlDefault(1) = "<addrdata>"
strXmlDefault(2) = "</addrdata>"
File.WriteAllLines(xmlfile, strXmlDefault)
End Sub

由于.net平台下C#和vb.NET很相似，本文也可以为C#爱好者提供参考。

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