form1.vb

编程之道VB.NETt程序设计入门-589M.zip

Public Class Form1
    Inherits System.Windows.Forms.Form

#Region " Windows 窗体设计器生成的代码 "

    Public Sub New()
        MyBase.New()

        '该调用是 Windows 窗体设计器所必需的。
        InitializeComponent()

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

    End Sub

    '窗体重写处置以清理组件列表。
    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 窗体设计器所必需的
    Private components As System.ComponentModel.IContainer

    '注意：以下过程是 Windows 窗体设计器所必需的
    '可以使用 Windows 窗体设计器修改此过程。
    '不要使用代码编辑器修改它。
    Friend WithEvents btnOpen As System.Windows.Forms.Button
    Friend WithEvents btnSave As System.Windows.Forms.Button
    Friend WithEvents dlgOpenFile As System.Windows.Forms.OpenFileDialog
    Friend WithEvents txtFileText As System.Windows.Forms.TextBox
    Friend WithEvents btnNew As System.Windows.Forms.Button
    Friend WithEvents dlgSaveFile As System.Windows.Forms.SaveFileDialog
    Friend WithEvents btnSaveAs As System.Windows.Forms.Button
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.txtFileText = New System.Windows.Forms.TextBox()
        Me.btnOpen = New System.Windows.Forms.Button()
        Me.btnSave = New System.Windows.Forms.Button()
        Me.dlgOpenFile = New System.Windows.Forms.OpenFileDialog()
        Me.btnNew = New System.Windows.Forms.Button()
        Me.dlgSaveFile = New System.Windows.Forms.SaveFileDialog()
        Me.btnSaveAs = New System.Windows.Forms.Button()
        Me.SuspendLayout()
        '
        'txtFileText
        '
        Me.txtFileText.Anchor = (((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom) _
                    Or System.Windows.Forms.AnchorStyles.Left) _
                    Or System.Windows.Forms.AnchorStyles.Right)
        Me.txtFileText.Multiline = True
        Me.txtFileText.Name = "txtFileText"
        Me.txtFileText.ScrollBars = System.Windows.Forms.ScrollBars.Both
        Me.txtFileText.Size = New System.Drawing.Size(552, 320)
        Me.txtFileText.TabIndex = 0
        Me.txtFileText.Text = ""
        '
        'btnOpen
        '
        Me.btnOpen.Anchor = (System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Left)
        Me.btnOpen.Location = New System.Drawing.Point(88, 328)
        Me.btnOpen.Name = "btnOpen"
        Me.btnOpen.Size = New System.Drawing.Size(64, 32)
        Me.btnOpen.TabIndex = 1
        Me.btnOpen.Text = "打开"
        '
        'btnSave
        '
        Me.btnSave.Anchor = (System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Left)
        Me.btnSave.Location = New System.Drawing.Point(168, 328)
        Me.btnSave.Name = "btnSave"
        Me.btnSave.Size = New System.Drawing.Size(64, 32)
        Me.btnSave.TabIndex = 2
        Me.btnSave.Text = "保存"
        '
        'btnNew
        '
        Me.btnNew.Anchor = (System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Left)
        Me.btnNew.Location = New System.Drawing.Point(8, 328)
        Me.btnNew.Name = "btnNew"
        Me.btnNew.Size = New System.Drawing.Size(64, 32)
        Me.btnNew.TabIndex = 1
        Me.btnNew.Text = "新建"
        '
        'dlgSaveFile
        '
        Me.dlgSaveFile.FileName = "doc1"
        '
        'btnSaveAs
        '
        Me.btnSaveAs.Anchor = (System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Left)
        Me.btnSaveAs.Location = New System.Drawing.Point(248, 328)
        Me.btnSaveAs.Name = "btnSaveAs"
        Me.btnSaveAs.Size = New System.Drawing.Size(64, 32)
        Me.btnSaveAs.TabIndex = 3
        Me.btnSaveAs.Text = "另存为"
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)
        Me.ClientSize = New System.Drawing.Size(552, 366)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.btnSaveAs, Me.btnSave, Me.btnOpen, Me.txtFileText, Me.btnNew})
        Me.Name = "Form1"
        Me.Text = "Form1"
        Me.ResumeLayout(False)

    End Sub

#End Region

    '保存文件的打开方法，True表示文件是新建的
    'False表示文件是已经存在的
    Dim bNewFile As Boolean = True

    '保存用户打开的文件的名字
    Dim sOpenedFileName As String

    Private Sub SaveAsNewFile()
        '实现“另存为”的功能，实际上，另存为就等于
        '
        '1. 打开一个对话框让用户输入文件名
        '2. 保存文件

        If dlgSaveFile.ShowDialog() = DialogResult.OK Then
            Dim sFileName As String = dlgSaveFile.FileName

            SaveFile(sFileName)
        End If
    End Sub

    Private Sub SaveFile(ByVal sFileName As String)
        Dim stmWriter As IO.StreamWriter
        Try
            '建立（也可能是覆盖原来的）文件
            stmWriter = IO.File.CreateText(sFileName)

            '把对话框内容写入文件中
            stmWriter.Write(txtFileText.Text)

            '把缓冲区中的内容完全写入文件中
            stmWriter.Flush()
        Catch ex As Exception
            MsgBox("无法保存文件" + vbCrLf + _
                "请检查文件名并确保您拥有对介质的写入权限 " + _
                 +vbCrLf + vbCrLf + "错误信息： " + ex.Message)
        Finally
            '关闭文件
            If Not stmWriter Is Nothing Then
                stmWriter.Close()
            End If
        End Try
    End Sub

    Private Sub OpenFile()
        dlgOpenFile.CheckFileExists = True
        dlgOpenFile.DefaultExt = "txt"
        dlgOpenFile.InitialDirectory = "C:\"
        dlgOpenFile.Multiselect = False

        If dlgOpenFile.ShowDialog = DialogResult.OK Then

            '把用户选择的文件完整路径保存下来，因为在保存文件的时候可能会用
            sOpenedFileName = dlgOpenFile.FileName

            Dim stmReader As IO.StreamReader
            Try
                '打开文件，准备读入
                stmReader = IO.File.OpenText(sOpenedFileName)

                '把文件内容读入到文本框中
                txtFileText.Text = stmReader.ReadToEnd()
            Catch ex As Exception
                MsgBox("无法打开文件" + vbCrLf + _
                    "请检查文件名并确保您拥有对文件的读取权限 " + _
                     +vbCrLf + vbCrLf + "错误信息： " + ex.Message)
            Finally
                '文件内容已经读入了，现在可以关闭文件了
                If Not stmReader Is Nothing Then
                    stmReader.Close()
                End If
            End Try

            '文件不是新建的，把bNewFile置为False
            bNewFile = False
        End If

    End Sub

    Private Sub btnOpen_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOpen.Click
        OpenFile()
    End Sub

    Private Sub btnNew_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnNew.Click
        txtFileText.Clear()
        bNewFile = True
    End Sub

    Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click

        '如果文件是新建的，则应该显示保存文件对话框，否则直接覆盖原来的文件
        If bNewFile Then
            SaveAsNewFile()
        Else
            SaveFile(sOpenedFileName)
        End If
    End Sub

    Private Sub btnSaveAs_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSaveAs.Click
        SaveAsNewFile()
    End Sub

End Class