在循环的不同迭代中产生相同值的随机字符串

Question

我在函数中创建referenceid并将值添加到列表中。

Dim myListOfItems As New List(Of BasketItem)      
Dim refID As String = String.Empty

For Each i In myListOfNames
refID = HelpClass.GenerateRandomString(20)
Dim x As New BasketItem
x.RefID = refID
myListOfItems.Add(x)
Next

函数如下所示:

Public Shared Function GenerateRandomString(ByVal length As Integer) As String
Dim chara As Char() = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".ToCharArray()
Dim randomString As String = String.Empty
Dim objRandom As New Random()
For i As Integer = 0 To length Step 1
Dim x As Integer = objRandom.Next(1, chara.Length)
If Not randomString.Contains(chara.GetValue(x).ToString()) Then
randomString += chara.GetValue(x)
Else
i = i - 1
End If
Next
Return randomString
End Function

这在我本地的visual studio运行中都很有效。但是当我上传到我的web服务器的几个项目得到相同的值。

这是在运行服务器上的输出:

> Biljettinnehavare: 1 | 1XIh4YqBlHmipkPKV576C  
> Biljettinnehavare: 2 | 1XIh4YqBlHmipkPKV576C 
> Biljettinnehavare: 3 | 1XIh4YqBlHmipkPKV576C 
> Biljettinnehavare: 4 | 1XIh4YqBlHmipkPKV576C 
> Biljettinnehavare: 5 | qvmupeZhcoQ9YgOWtCLN4 
> Biljettinnehavare: 6 | qvmupeZhcoQ9YgOWtCLN4  
> Biljettinnehavare: 7 | qvmupeZhcoQ9YgOWtCLN4  
> Biljettinnehavare: 8 | qvmupeZhcoQ9YgOWtCLN4  
> Biljettinnehavare: 9 | qvmupeZhcoQ9YgOWtCLN4  
> Biljettinnehavare: 10 | qvmupeZhcoQ9YgOWtCLN4 
> Biljettinnehavare: 11 | DdxK4jibcu9s7gXJw6a3m  
> Biljettinnehavare: 12 | DdxK4jibcu9s7gXJw6a3m  
> Biljettinnehavare: 13 | DdxK4jibcu9s7gXJw6a3m 
> Biljettinnehavare: 14 | DdxK4jibcu9s7gXJw6a3m
> Biljettinnehavare: 15 | 32SWpkFfdgbqMtJGa1siw 
> Biljettinnehavare: 16 | 32SWpkFfdgbqMtJGa1siw

我真的不知道是什么引起了这个问题。什么好主意吗?

服务器执行循环如此之快，并基于时钟使相同的值出现，在这种情况下，如何应对?

Answer 1

将变量定义为:

Static objRandom As System.Random = New System.Random()

在VB中的答案随机整数。净