တစ်ခါ တလေ Visual Basic 2005 ကိုသုံးပြီး ဖိုင်တွေရေးဖို့ ဖတ်ဖို့ လိုတတ်ပါတယ်။ အဲဒီ အခါ အလွယ်တကူ ကိုးကားလို့ရအောင် တစ်ချို့ ကုဒ်လေးတွေ ကို တင်လိုက်ပါတယ်။ အောက်က နမူနာ နှစ်ခုကတော့ ဒီနေရာက နေ ကိုးကားထားတာပါ။
Dim objStreamReader As StreamReader
Dim strLine As String
'Pass the file path and the file name to the StreamReader constructor.
objStreamReader = New StreamReader("C:\Boot.ini")
'Read the first line of text.
strLine = objStreamReader.ReadLine
'Continue to read until you reach the end of the file.
Do While Not strLine Is Nothing
'Write the line to the Console window.
Console.WriteLine(strLine)
'Read the next line.
strLine = objStreamReader.ReadLine
Loop
'Close the file.
objStreamReader.Close()
Dim objStreamWriter As StreamWriter
'Pass the file path and the file name to the StreamWriter constructor.
objStreamWriter = New StreamWriter("C:\Testfile.txt")
'Write a line of text.
objStreamWriter.WriteLine("Hello World")
'Write a second line of text.
objStreamWriter.WriteLine("From the StreamWriter class")
'Close the file.
objStreamWriter.Close()
ဖိုင်ကိုသုံးနေတုန်း error တက်ခဲ့ရင် တော့ သုံးလက်စ ဖိုင်ကို မပိတ်နိုင်ပဲ ထွက်သွားတာမျိုး ဖြစ်နိုင်ပါတယ်။ အဲဒါကို တားဆီးဖို့ ကတော့ Try ... Finally ကိုအောက်ပါအတိုင်း သုံးနိုင်ပါတယ်။
Dim strLine As String
Dim sr As StreamReader = Nothing
Try
sr = New StreamReader(fileName)
strLine = sr.ReadToEnd()
Finally
sr.Close()
End Try
Visual Basic 2005 မှာ Using ဆိုတဲ့ statement အသစ် က IDisposable object တွေကို အလိုအလျောက် release လုပ်ပေးနိုင်ပါတယ်။ Exception တစ်ခုခု ဖြစ်ရင် သူ့ရဲ့ caller ဆီကိုရောက်သွားမှာပါ။ အကယ်၍ အဲဒီ exception ကို ကိုယ့်ဟာကိုယ် catch လုပ်ချင်ရင်တော့ Try ... Catch ... Finally block ကိုပဲ သုံးရမှာပါ။
Dim strLine As String
Using sr As New StreamReader(fileName)
strLine = sr.ReadToEnd
End Using
ဖိုင်ဖတ်တဲ့ အခါ ပိုပြီးလွယ်ကူ ရှင်းလင်း ချင်ရင် File.ReadAllText or File.ReadAllBytes static method ကိုသုံးလို့လဲ ရပါတယ်။
Log File
Log files တွေ အလွယ်တကူ ရေးဖို့ class တစ်ခု ကို ရေးကြည့် ထားပါတယ်။ သူ့ရဲ့ ကုဒ်တွေကို VB class for log file on GitHub ကနေ ယူလို့ သုံးလို့ ရပါတယ်။
'Author: Yan Naing Aye
'WebSite: http://cool-emerald.blogspot.sg/
'Updated: 2009 June 25
'-----------------------------------------------------------------------------
Imports System.IO
Public Class ClsLog
Private mEnableLog As Boolean = False
Private mLogFileDirectory As String = ""
Private mLogFilePath As String = ""
Private mLogFileLifeSpan As Integer = 0
Private mLogFileFirstName As String = "AppName"
Public Sub New()
mEnableLog = False
mLogFileDirectory = My.Application.Info.DirectoryPath
mLogFileLifeSpan = 0
mLogFileFirstName = My.Application.Info.AssemblyName
End Sub
Public Property LogFileLifeSpan() As Integer
Get
Return mLogFileLifeSpan
End Get
Set(ByVal value As Integer)
mLogFileLifeSpan = IIf(value >= 0, value, 0)
End Set
End Property
Public Property LogFileFirstName() As String
Get
Return mLogFileFirstName
End Get
Set(ByVal value As String)
mLogFileFirstName = value
End Set
End Property
Public Property LogEnable() As Boolean
Get
Return mEnableLog
End Get
Set(ByVal value As Boolean)
If value = True Then
If Directory.Exists(Me.LogFileDirectory) Then
mEnableLog = value
Else
mEnableLog = False
Throw New Exception("Invalid file directory.")
End If
Else
mEnableLog = value
End If
End Set
End Property
Public Property LogFileDirectory() As String
Get
Return mLogFileDirectory
End Get
Set(ByVal value As String)
value = Trim(value)
If Directory.Exists(value) Then
Dim i As Integer = value.Length - 1
If (((value(i)) = "\") OrElse ((value(i)) = "/")) Then
value = value.Substring(0, i)
End If
mLogFileDirectory = value
Else
Throw New Exception("Invalid file directory.")
End If
End Set
End Property
Public ReadOnly Property LogFilePath() As String
Get
Return mLogFileDirectory & "\" & mLogFileFirstName & Format(Now, "-yyyy-MMM-dd") & ".log"
End Get
End Property
Public Sub WriteLog(ByVal LogEntry As String)
If mEnableLog = True Then
mLogFilePath = mLogFileDirectory & "\" & mLogFileFirstName & Format(Now, "-yyyy-MMM-dd") & ".log"
Dim objStreamWriter As StreamWriter = New StreamWriter(mLogFilePath, True)
Try
objStreamWriter.WriteLine(LogEntry)
Catch ex As Exception
Finally
objStreamWriter.Close()
End Try
End If
End Sub
Public Sub WriteTimeAndLog(ByVal LogEntry As String)
WriteLog(Now.ToLongTimeString & " " & LogEntry)
End Sub
Public Sub CleanupFiles()
If mLogFileLifeSpan > 0 Then 'if life span is zero, there will be no cleaning up
Try
Dim LogFiles() As String = Directory.GetFiles(mLogFileDirectory)
For Each LogFile As String In LogFiles
If (DateDiff("d", File.GetLastWriteTime(LogFile), Now) > mLogFileLifeSpan) _
AndAlso (Right(LogFile, 4) = ".log") Then
File.Delete(LogFile)
End If
Next
Catch ex As Exception
End Try
End If
End Sub
End Class
