My.Application.Log.WriteEntry()与System.Diagnostics.Trace.Wri

Question

WriteEntry具有与Writeline完全不同的签名。还有一个My.Application.Log.WriteException（）。当我用程序添加侦听器时，WriteEntry不起作用。

 Trace.Listeners.Add(New Logging.FileLogTraceListener("stuff") With { _
                            .Append = False, _
                            .AutoFlush = True, _
                            .DiskSpaceExhaustedBehavior = Logging.DiskSpaceExhaustedOption.DiscardMessages, _
                            .Location = Logging.LogFileLocation.ExecutableDirectory, _
                            .TraceOutputOptions = TraceOptions.DateTime, _
                            .BaseFileName = GetExecutingAssembly.GetName.Name & "_" & Date.Now.ToString(ISO_LogFileNameFormat)})

有人能解释一下这些功能之间的关系吗？

Answer 1

要了解WriteEntry和Writeline之间的区别，请使用Reflector或ILSpy并深入查看内部实现。System.Diagnostics.Trace.WriteLine:

Public Shared Sub WriteLine(ByVal value As Object)
    If TraceInternal.UseGlobalLock Then
        SyncLock TraceInternal.critSec
            Dim listener As TraceListener
            For Each listener In TraceInternal.Listeners
                listener.WriteLine(value)
                If TraceInternal.AutoFlush Then
                    listener.Flush
                End If
            Next
            Return
        End SyncLock
    End If
    Dim listener2 As TraceListener
    For Each listener2 In TraceInternal.Listeners
        If Not listener2.IsThreadSafe Then
            SyncLock listener2
                listener2.WriteLine(value)
                If TraceInternal.AutoFlush Then
                    listener2.Flush
                End If
                Continue For
            End SyncLock
        End If
        listener2.WriteLine(value)
        If TraceInternal.AutoFlush Then
            listener2.Flush
        End If
    Next
End Sub

My.Application.Log.WriteEntry只是一个LOP语法，但它实际上指向名称空间Microsoft.VisualBasic.Logging.Log.WriteEntry:

Public Sub WriteEntry(ByVal message As String, ByVal severity As TraceEventType, ByVal id As Integer)
    If (message Is Nothing) Then
        message = ""
    End If
    Me.m_TraceSource.TraceEvent(severity, id, message)
End Sub

要以编程方式设置它，您可以这样做：

Dim listener As New FileLogTraceListener()
listener.Location = LogFileLocation.TempDirectory
listener.BaseFileName = "ConsoleApp_"
listener.Append = True
listener.Delimiter = "|"
listener.AutoFlush = True

通常情况下，您会在配置文件中对其进行配置：

<system.diagnostics>
   <sources>
      <source name="TestSrc">
         <listeners>
               <add name="FileLogger" type="Microsoft.VisualBasic.Logging.FileLogTraceListener,
                           Microsoft.VisualBasic,Version=8.0.0.0,Culture=Neutral, PublicKeyToken=b03f5f7f11d50a3a"/>
        </listeners>
     </source>
   </sources>
</system.diagnostics>

然后你可以这样使用它：

Debug.Listeners.Add(listener)
Debug.WriteLine("Testing 1 2 3")