Public Class frmMain
    Inherits System.Windows.Forms.Form

#Region " Windows 窗體設(shè)計(jì)器生成的代碼 "

    Public Sub New()
        MyBase.New()

        '該調(diào)用是 Windows 窗體設(shè)計(jì)器所必需的。
        InitializeComponent()

        '在 InitializeComponent() 調(diào)用之后添加任何初始化

    End Sub

    '窗體重寫處置以清理組件列表。
    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

    'Windows 窗體設(shè)計(jì)器所必需的
    Private components As System.ComponentModel.IContainer

    '注意：以下過(guò)程是 Windows 窗體設(shè)計(jì)器所必需的
    '可以使用 Windows 窗體設(shè)計(jì)器修改此過(guò)程。
    '不要使用代碼編輯器修改它。
    Friend WithEvents Label1 As System.Windows.Forms.Label
    Friend WithEvents Label2 As System.Windows.Forms.Label
    Friend WithEvents txtHostname As System.Windows.Forms.TextBox
    Friend WithEvents txtIP As System.Windows.Forms.TextBox
    Friend WithEvents btnLocal As System.Windows.Forms.Button
    Friend WithEvents btnIPtoHost As System.Windows.Forms.Button
    Friend WithEvents btnHosttoIP As System.Windows.Forms.Button
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.Label1 = New System.Windows.Forms.Label()
        Me.Label2 = New System.Windows.Forms.Label()
        Me.txtHostname = New System.Windows.Forms.TextBox()
        Me.txtIP = New System.Windows.Forms.TextBox()
        Me.btnLocal = New System.Windows.Forms.Button()
        Me.btnIPtoHost = New System.Windows.Forms.Button()
        Me.btnHosttoIP = New System.Windows.Forms.Button()
        Me.SuspendLayout()
        '
        'Label1
        '
        Me.Label1.Location = New System.Drawing.Point(24, 32)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(72, 16)
        Me.Label1.TabIndex = 0
        Me.Label1.Text = "計(jì)算機(jī)名："
        '
        'Label2
        '
        Me.Label2.Location = New System.Drawing.Point(24, 64)
        Me.Label2.Name = "Label2"
        Me.Label2.Size = New System.Drawing.Size(72, 13)
        Me.Label2.TabIndex = 1
        Me.Label2.Text = "IP地址："
        '
        'txtHostname
        '
        Me.txtHostname.Location = New System.Drawing.Point(104, 24)
        Me.txtHostname.Name = "txtHostname"
        Me.txtHostname.Size = New System.Drawing.Size(152, 21)
        Me.txtHostname.TabIndex = 2
        Me.txtHostname.Text = ""
        '
        'txtIP
        '
        Me.txtIP.Location = New System.Drawing.Point(104, 56)
        Me.txtIP.Name = "txtIP"
        Me.txtIP.Size = New System.Drawing.Size(152, 21)
        Me.txtIP.TabIndex = 3
        Me.txtIP.Text = ""
        '
        'btnLocal
        '
        Me.btnLocal.Location = New System.Drawing.Point(64, 96)
        Me.btnLocal.Name = "btnLocal"
        Me.btnLocal.Size = New System.Drawing.Size(144, 32)
        Me.btnLocal.TabIndex = 4
        Me.btnLocal.Text = "本機(jī)名稱和IP"
        '
        'btnIPtoHost
        '
        Me.btnIPtoHost.Location = New System.Drawing.Point(64, 144)
        Me.btnIPtoHost.Name = "btnIPtoHost"
        Me.btnIPtoHost.Size = New System.Drawing.Size(144, 32)
        Me.btnIPtoHost.TabIndex = 5
        Me.btnIPtoHost.Text = "IP->計(jì)算機(jī)名"
        '
        'btnHosttoIP
        '
        Me.btnHosttoIP.Location = New System.Drawing.Point(64, 192)
        Me.btnHosttoIP.Name = "btnHosttoIP"
        Me.btnHosttoIP.Size = New System.Drawing.Size(144, 32)
        Me.btnHosttoIP.TabIndex = 6
        Me.btnHosttoIP.Text = "計(jì)算機(jī)名－>IP"
        '
        'frmMain
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)
        Me.ClientSize = New System.Drawing.Size(288, 262)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.btnHosttoIP, Me.btnIPtoHost, Me.btnLocal, Me.txtIP, Me.txtHostname, Me.Label2, Me.Label1})
        Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.Fixed3D
        Me.MaximizeBox = False
        Me.Name = "frmMain"
        Me.Text = "獲取計(jì)算機(jī)名和IP"
        Me.ResumeLayout(False)

    End Sub

#End Region

    Private Sub btnHosttoIP_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnHosttoIP.Click
        '根據(jù)輸入的計(jì)算機(jī)名獲取其IP地址
        Dim name As String
        name = txtHostname.Text
        'JudgeName()函數(shù)用于判斷輸入的計(jì)算機(jī)名是否合法
        '合法則返回True，否則返回False
        If JudgeName(name) Then
            Try
                '獲取該計(jì)算機(jī)的IP地址并顯示
                Dim ip As String
                Dim Address() As System.Net.IPAddress
                Address = System.Net.Dns.GetHostByName(name).AddressList
                ip = Address(0).ToString
                txtIP.Text = ip
            Catch ex As Exception
                '顯示異常信息
                MessageBox.Show("發(fā)生錯(cuò)誤：" + ex.Message)
            End Try
            txtHostname.Focus()
            txtHostname.SelectionStart = 0
            txtHostname.SelectionLength = txtHostname.Text.Length
        Else
            '若輸入的計(jì)算機(jī)名不合法，則提示錯(cuò)誤
            MessageBox.Show("不存在主機(jī)！")
            '焦點(diǎn)重定向到txthostname控件讓用戶重新輸入
            txtHostname.Focus()
            txtHostname.SelectionStart = 0
            txtHostname.SelectionLength = txtHostname.Text.Length
        End If
    End Sub

    Private Function JudgeIP(ByVal ip As String) As Boolean
        'numcount用于統(tǒng)計(jì)連續(xù)的數(shù)字個(gè)數(shù)
        Dim numcount As Integer = 0
        'dotcount用于統(tǒng)計(jì)該字符串中"."的個(gè)數(shù)
        Dim dotcount As Integer = 0
        '合法的IP地址字符串長(zhǎng)度不小于7
        If ip.Length < 7 Then
            Return False
        End If
        '判斷首位是否為數(shù)字
        If Char.IsDigit(ip.Chars(0)) = False Then
            Return False
        Else
            numcount += 1
        End If
        Dim i As Integer
        '依次判斷各位字符是否為數(shù)字或"."
        For i = 1 To ip.Length - 1
            If Char.IsDigit(ip.Chars(i)) Then
                '若該字符為數(shù)字
                numcount += 1
                '連續(xù)數(shù)字不得超過(guò)3位
                If numcount > 3 Then
                    Return False
                End If
                '若為3位，則其值不得超過(guò)255
                If numcount = 3 Then
                    Dim a, b, c As Integer
                    a = Char.GetNumericValue(ip.Chars(i - 2))
                    b = Char.GetNumericValue(ip.Chars(i - 1))
                    c = Char.GetNumericValue(ip.Chars(i))
                    If a * 100 + b * 10 + c > 255 Then
                        Return False
                    End If
                End If
            ElseIf ip.Chars(i) = "." Then
                '若該字符為點(diǎn)
                '如果該點(diǎn)與前一點(diǎn)之間沒(méi)有任何數(shù)字，則該IP地址非法
                If numcount = 0 Then
                    Return False
                End If
                numcount = 0
                dotcount += 1
            Else
                '若為其他字符，則該IP地址非法
                Return False
            End If
        Next
        '最后，點(diǎn)的總數(shù)應(yīng)為3個(gè)
        If dotcount <> 3 Then
            Return False
        End If
        '最后一位字符應(yīng)該是數(shù)字
        If Not Char.IsDigit(ip.Chars(ip.Length - 1)) Then
            Return False
        End If
        Return True
    End Function

    Private Function JudgeName(ByVal name As String) As Boolean
        If name.Length = 0 Then
            Return False
        End If
        Dim i As Integer
        Dim flag As Boolean = False
        For i = 0 To name.Length - 1
            If Char.IsLetterOrDigit(name.Chars(i)) Then
                '該字符是字母或數(shù)字
                flag = True
            ElseIf name.Chars(i) = "-" Then
                '該字符是連接符"-"
                flag = True
            End If
            If flag = False Then
                Return False
            End If
        Next
        Return True
    End Function

    Private Sub btnLocal_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLocal.Click
        '獲取本地主機(jī)的計(jì)算機(jī)名及IP地址并顯示
        Try
            Dim Address() As System.Net.IPAddress
            Dim name As String
            '獲取本地主機(jī)的計(jì)算機(jī)名
            name = System.Net.Dns.GetHostName()
            txtHostname.Text = name
            '獲取本地主機(jī)的IP地址列表
            Address = System.Net.Dns.GetHostByName(name).AddressList
            '獲取主機(jī)的首個(gè)IP地址
            txtIP.Text = Address(0).ToString
        Catch ex As Exception
            '捕捉到異常，顯示其信息
            MessageBox.Show("發(fā)生錯(cuò)誤：" + ex.Message)
        End Try
        txtIP.Focus()
        '設(shè)置txtip控件中的內(nèi)容為被選中
        txtIP.SelectionStart = 0
        txtIP.SelectionLength = txtIP.Text.Length
    End Sub

    Private Sub btnIPtoHost_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnIPtoHost.Click
        '根據(jù)輸入的IP地址獲取其計(jì)算機(jī)名
        Dim ip As String
        ip = txtIP.Text
        'JudgeIP()函數(shù)用于判斷輸入的IP地址是否合法
        '合法則返回True，否則返回False
        If JudgeIP(ip) Then
            Try
                '獲取該計(jì)算機(jī)的名稱并顯示
                Dim name As String
                name = System.Net.Dns.GetHostByAddress(ip).HostName
                txtHostname.Text = name
            Catch ex As Exception
                '顯示異常信息
                MessageBox.Show("發(fā)生錯(cuò)誤：" + ex.Message)
            End Try
            txtIP.Focus()
            txtIP.SelectionStart = 0
            txtIP.SelectionLength = txtIP.Text.Length
        Else
            '若輸入的IP地址不合法，則提示錯(cuò)誤
            MessageBox.Show("不存在此IP！")
            '焦點(diǎn)重定向到txtip控件讓用戶重新輸入
            txtIP.Focus()
            txtIP.SelectionStart = 0
            txtIP.SelectionLength = txtIP.Text.Length
        End If
    End Sub
End Class