Question

怎样用vb.net读取本地.txt文件？

我在写一个程序，用的语言是vb.net，设计视图是一个简单的页面，上面有“On”跟“Off”两个Button。

现在我想要在点击“On”的时候，程序自动读取本地文件A.txt（这个文件的内容只有一个字母“A”），让A.txt里面的内容（就是字母A了）自动发送给与电脑连接的电路板，让电路板上的灯亮起来；而在点击“Off”的时候读取本地文件B.txt（文件内容只有一个字母“B”），从而自动发送字母B到电路板，使灯熄灭。
（注：电路板的程序为收到A就开灯，收到B就关灯。）

我不知道这段读取及发送内容到电路板的命令要怎么写，希望各位懂vb.net的大大不吝赐教，感激涕零！！！（如果没弄明白我的问题，可以再问我，因为在这方面实在是太菜了，所以连表达都不清楚了。）谢谢！顺便祝看贴的各位圣诞快乐&元旦快乐！ ^_^
以下是我的源码：

Public Class Form1
Dim fp As IO.StreamReader

Private Sub btnON_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnON.Click
Try
lblMessage.Text = "LED is turn on."
btnON.Enabled = False
btnOFF.Enabled = True
Catch ex As Exception
MsgBox(ex.ToString)
End Try
End Sub

Private Sub btnDisconnect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOFF.Click
Try
lblMessage.Text = "LED is turn off."
btnON.Enabled = True
btnOFF.Enabled = False
Catch ex As Exception
MsgBox(ex.ToString)
End Try
End Sub

End Class

很愚的我意识到一个问题，像我的这种要求应该是嵌入（embed）文件而不是读取文件吧？？？请教各位大大我的认识对不对......

Answer 1

imports System.IO

读取指定文件
'
'读取指定文本文件
Public Function readtext(ByVal path As String)
If path = "" Then
readtext = "操作失败！"
Exit Function
End If
Try
If File.Exists(path) = True Then
Dim fs As New FileStream(path, FileMode.Open)
Dim sr As New StreamReader(fs)
Dim str As String
str = sr.ReadToEnd.ToString
sr.Close()
fs.Close()
readtext = str
Else
readtext = "操作失败！"
End If
Catch ex As Exception
readtext = "操作失败！"
End Try
End Function
'向指定文件写入数据
Public Function writetext(ByVal path As String, ByVal opi As Integer, ByVal msg As String)
If path = "" Then
writetext = "操作失败！"
Exit Function
End If
Dim op As FileMode
Select Case opi
Case 1
op = FileMode.Append
Case 2
op = FileMode.Create
Case Else
op = FileMode.Create
End Select
Try
If File.Exists(path) = True Then
Dim fs As New FileStream(path, op)
Dim sr As New StreamWriter(fs)
sr.WriteLine(msg)
sr.Close()
fs.Close()
writetext = "操作完成！"
Else
writetext = "操作失败！"
End If
Catch ex As Exception
writetext = "操作失败！"
End Try
End Function

参考这个吧
'
'vb.net源代码来自www.c-pet.com
'

Answer 2

引用：
System.IO

读取：
StreamReader sr=new StreamReader("a.txt");
string s = sr.ReadToEnd();
sr.Close();

Answer 3

圣诞节快乐~！