用以在记录文件中写入自定义的调试信息（主要是时间）的组件

'====================================================================
'TraceSpy - 用以在记录文件中写入自定义的调试信息（开发者：林健）
'====================================================================
'
'属性：
'       TraceFileName        - 记录文件名
'
'方法：
'   ★文本写入方面
'       WriteText            - 写入自定义文本
'       ClearAllText         - 清除所有文本
'   ★时间记录方面
'       SetTimePoint         - 设置时间起点
'       GetTimeSpanFromInit  - 询问时间跨度（距离时间起点）
'       GetTimeSpanFromPrev  - 询问时间跨度（距离上次询问时间）
'
'====================================================================

Public Class TraceSpy

    '记录文件名
    Public Shared TraceFileName As String = "Trace.txt"

    '时间起点（初始为当前时刻）
    Private Shared InitTimePoint As Long = Now.Ticks

    '上次询问时间点（初始为当前时刻）
    Private Shared PrevTimePoint As Long = Now.Ticks

    '写入自定义文本
    Public Shared Sub WriteText(ByVal str As String, Optional ByVal showTime As Boolean = False)
        TraceSpyFileWriter.WriteText(str, showTime)
    End Sub

    '清除所有文本
    Public Shared Sub ClearAllText()
        TraceSpyFileWriter.ClearAllText()
    End Sub

    '设置时间起点
    Public Shared Sub SetTimePoint(Optional ByVal note As String = "")
        InitTimePoint = Now.Ticks
        PrevTimePoint = Now.Ticks
        TraceSpyFileWriter.WriteText("设置时间起点[" & note & "]。")
    End Sub

    '询问时间跨度（距离时间起点）
    Public Shared Function GetTimeSpanFromInit(Optional ByVal note As String = "") As Decimal
        PrevTimePoint = Now.Ticks
        Dim span As Decimal
        span = CDec(PrevTimePoint - InitTimePoint) / 10000D
        TraceSpyFileWriter.WriteText("询问时间跨度[" & note & "]，距离时间起点为" & span.ToString() & "毫秒。")
        Return span
    End Function

    '询问时间跨度（距离上次询问时间）
    Public Shared Function GetTimeSpanFromPrev(Optional ByVal note As String = "") As Decimal
        Dim RectTimePoint As Long = Now.Ticks
        Dim span As Decimal
        span = CDec(RectTimePoint - PrevTimePoint) / 10000D
        PrevTimePoint = RectTimePoint
        TraceSpyFileWriter.WriteText("询问时间跨度[" & note & "]，距离上次询问时间为" & span.ToString() & "毫秒。")
        Return span
    End Function

End Class

Friend Class TraceSpyFileWriter

    Private Shared FileWriter As System.IO.StreamWriter

    '向文件中写入一个字串
    Friend Shared Sub WriteText(ByVal str As String, Optional ByVal showTime As Boolean = False)
        If TraceSpy.TraceFileName = String.Empty Then
            Exit Sub
        End If
        FileWriter = New System.IO.StreamWriter(TraceSpy.TraceFileName, True, Text.Encoding.Default)
        Dim words As String
        words = str
        If showTime Then
            words &= " @ " & Now.ToLongDateString & " " & Now.ToLongTimeString
        End If
        FileWriter.WriteLine(words)
        FileWriter.Close()
    End Sub

    '清除记录文件
    Friend Shared Sub ClearAllText()
        If TraceSpy.TraceFileName = String.Empty Then
            Exit Sub
        End If
        FileWriter = New System.IO.StreamWriter(TraceSpy.TraceFileName, False, Text.Encoding.Default)
        FileWriter.Write("")
        FileWriter.Close()
    End Sub

End Class

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