050使用文件对话框

1.添加方本框

2.添加菜单
    名称为mainMenu。为菜单添加一个文件菜单项，其中包含子菜单项’“新建"，“打开…”。  “保存”和“另存为…”。

3.新建事件

 Private filename As String = "未命名文档"
    Private Sub NewMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles NewMenuItem.Click
        filename = "未命名文档"
        txtBoxEdit.Clear()
    End Sub

4.向窗体添加OpenFileDialog控件，将其Name属性修改为OpenFileDlg，Filter属性设置为下列字符串，并将Fiiterlndex的属性设置为2，使所有文件成为默认选项。

     文本文件(*.txt)|*.txt|所有文件(*.*)|*.*

5.为“打开”菜单项添加事件处理程序，以显示“打开”对话框，读取选中的文件。

Private filename As String = "未命名文档"
    Private Sub OpenMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OpenMenuItem.Click
        If OpenFileDlg.ShowDialog = Windows.Forms.DialogResult.OK Then
            filename = OpenFileDlg.FileName
            OpenFile()
        End If
    End Sub

    Private Sub OpenFile()
        Try
            txtBoxEdit.Clear()
            txtBoxEdit.Text = IO.File.ReadAllText(filename)
        Catch ex As Exception
            MessageBox.Show(ex.Message, "文本编辑器", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
        End Try
    End Sub

6.添加SaveFileDialog，设计Filter属性，名称改为SaveFileDlg

 文本文件(*.txt)|*.txt|所有文件(*.*)|*.*

7.为保存为添加事件

Private Sub SaveAsMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SaveAsMenuItem.Click
        If SaveFileDlg.ShowDialog = DialogResult.OK Then
            filename = SaveFileDlg.FileName
            SaveFile()
        End If
    End Sub
    Private Sub SaveFile()
        Try
            IO.File.WriteAllText(filename, txtBoxEdit.Text)
        Catch ex As Exception
            MessageBox.Show(ex.Message, "文本编辑器", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
        End Try
    End Sub

8.为保存添加事件

 Private Sub SaveMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SaveMenuItem.Click
        If filename = "未命名文档" Then
            SaveAsMenuItem.PerformClick()
        Else
            SaveFile()
        End If
    End Sub