vb.net 写日志文件

Module mod_LogAccessHt

#Region "Const"

    Public Const __PREFIX_ERROR__ As String = "Error_"
    Public Const __PREFIX_TRACE__ As String = "Trace_"
    Public Const __PREFIX_DEBUG__ As String = "Debug_"
    Public Const __PREFIX_SQL__ As String = "Sql_"

#End Region

    ''' <summary>
    ''' ログレベル
    ''' </summary>
    ''' <remarks></remarks>
    Public Enum enumLogLevel As Integer
        __LOG_LVL_EMERG__   ' system is unusable
        __LOG_LVL_ALERT__   ' action must be taken immediately
        __LOG_LVL_CRIT__    ' critical conditions
        __LOG_LVL_ERR__     ' error conditions
        __LOG_LVL_WARN__    ' warning conditions
        __LOG_LVL_NOTE__    ' normal but significant condition
        __LOG_LVL_INFO__    ' informational
        __LOG_LVL_DEBUG__   ' debug-level messages
        __LOG_LVL_SQL__     ' issued SQL string
    End Enum

    ''' <summary>
    ''' ログアクセスクラス
    ''' </summary>
    ''' <remarks></remarks>
    Public Class cls_LogAccess

        Private Const __LOG_DIR__ As String = "log_dir"
        Private Const __LOG_EXT__ As String = ".log"

        Private m_strPreFix As String

        ' コンストラクタ
        Public Sub New(ByVal preFix As String)
            m_strPreFix = preFix
        End Sub

        ''' <summary>
        ''' ログ出力
        ''' </summary>
        ''' <param name="msg">メッセージ</param>
        ''' <param name="ex">Exception(無指定の場合はメッセージのみ出力)</param>
        ''' <remarks></remarks>
        Public Sub WriteLog( _
            ByVal msg As String, Optional ByVal ex As Exception = Nothing)
            Try
                ' 設定ファイル取得
                Dim clsProf As cls_Profile = fnc_GetProfile()
                clsProf.SetSection(__ROOT_SECTION__)

                ' ログフォルダ名取得
                Dim logFolder As String = clsProf.GetProfileString(__LOG_DIR__)

                If logFolder = "" Then
                    ' ログフォルダ名作成
                    logFolder = System.AppDomain.CurrentDomain.BaseDirectory & "Log"
                End If

                ' ログフォルダ名作成
                System.IO.Directory.CreateDirectory(logFolder)

                ' ログファイル名作成
                Dim dt As DateTime = Now
                Dim logFile As String = logFolder & "" & m_strPreFix & dt.ToString("dd") & __LOG_EXT__

                ' 前月翌日分のログファイル削除(１ヶ月分のログファイルしか保存しないようにするため)
                Dim logNext As String = _
                    logFolder & "" & m_strPreFix & dt.AddDays(1).ToString("dd") & __LOG_EXT__
                System.IO.File.Delete(logNext)

                ' ログ出力文字列作成
                Dim logStr As String
                logStr = dt.ToString("yyyy/MM/dd HH:mm:ss") & vbTab & msg
                If ex Is Nothing = False Then
                    logStr = logStr & vbCrLf & ex.ToString
                End If

                ' Shift-JISでログ出力
                Dim sw As IO.StreamWriter = Nothing
                Try
                    sw = New IO.StreamWriter(logFile, True, _
                        System.Text.Encoding.GetEncoding("Shift-JIS"))
                    sw.WriteLine(logStr)
                Catch ex2 As Exception
                Finally
                    If sw Is Nothing = False Then sw.Close()
                End Try
            Catch ex2 As Exception
            End Try
        End Sub

        Public Sub WriteErrorLog(ByVal kind As Integer, ByVal msg As String, Optional ByVal ex As Exception = Nothing)

            Dim strMsg As String = ""

            Select Case kind
                Case enumLogLevel.__LOG_LVL_EMERG__     ' system is unusable
                    strMsg = "[EMERG] "
                Case enumLogLevel.__LOG_LVL_ALERT__     ' action must be taken immediately
                    strMsg = "[ALART] "
                Case enumLogLevel.__LOG_LVL_CRIT__      ' critical conditions
                    strMsg = "[CRIT] "
                Case enumLogLevel.__LOG_LVL_ERR__       ' error conditions
                    strMsg = "[ERROR] "
                Case enumLogLevel.__LOG_LVL_WARN__      ' warning conditions
                    strMsg = "[WARN] "
                Case enumLogLevel.__LOG_LVL_NOTE__      ' normal but significant condition
                    strMsg = "[NOTE] "
                Case enumLogLevel.__LOG_LVL_INFO__      ' informational
                    strMsg = "[INFO] "
                Case enumLogLevel.__LOG_LVL_DEBUG__     ' debug-level messages
                    strMsg = "[DEBUG] "
                Case enumLogLevel.__LOG_LVL_SQL__       ' issued SQL string
                    strMsg = "[SQL] "
            End Select

            ' HT名が分かっていれば出力する
            If pstrHTNo Is Nothing OrElse pstrHTNo = "" Then
                strMsg &= "[  ]"
            Else
                strMsg &= "[" & pstrHTNo & "]"
            End If

            strMsg = strMsg & msg
            WriteLog(strMsg, ex)

        End Sub

    End Class

    ''' <summary>
    ''' ログファイル出力
    ''' </summary>
    ''' <param name="pre_fix">ログファイルの接頭語</param>
    ''' <param name="kind">ログレベル</param>
    ''' <param name="msg">出力文字列</param>
    ''' <param name="ex">エクセプション</param>
    ''' <remarks></remarks>
    Public Sub sub_WriteErrorLog(ByVal pre_fix As String, ByVal kind As Integer, ByVal msg As String, Optional ByVal ex As Exception = Nothing)

        Dim clsLog As cls_LogAccess = New cls_LogAccess(pre_fix)
        clsLog.WriteErrorLog(kind, msg, ex)

    End Sub

End Module