Vb.net visualbasic中的安全复制文件

下面的代码是从C#代码中删除的。我想知道……的重要性是什么。。。。代码中的…语句

Public Sub CopyFile(sourceFile  As String, backupFile  As String, overwrite As Boolean)
If String.IsNullOrEmpty(sourceFile) Then
    Throw New ArgumentNullException("sourceFile")
End If
If String.IsNullOrEmpty(backupFile) Then
    Throw New ArgumentNullException("backupFile")
End If
' According to MSDN Certain file attributes, Hidden and ReadOnly, can be combined. Other attributes, such as Normal, must be used alone. 
If File.Exists(backupFile) Then
    File.SetAttributes(backupFile, FileAttributes.Normal)
End If
            ' ????????
For index As Integer = 0 To 9
    Try
        File.Copy(sourceFile, backupFile, overwrite)
        Exit Try
    Catch ex  As FileNotFoundException
        Throw
    Catch ex As Exception
        If Not overwrite Then
            Throw
        End If
        If index = 9 Then
            Throw
        End If
        Thread.Sleep(1000)
    End Try
Next
End Sub

---

看起来它正在设置重试循环-尝试10次，如果它不起作用并且不是另一个错误（未找到文件，或者

overwrite

为false的异常），则抛出异常。可能正在尝试访问被另一个进程锁定的文件。另一方面，您可以使用VB.Net的条件异常处理稍微简化此代码（…

Catch ex As exception When overwrite and also index<9

…）。