在循环的不同迭代中生成相同值的随机字符串

Question

我正在函数中创建引用 ID 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

这一切在我的本地 visual studio 运行上运行良好。但是当我上传到我的网络服务器时，有几个项目获得相同的值。

这是实时服务器上的输出：

> 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

真的不知道是什么导致了这个问题。有什么想法吗？

服务器执行循环的速度是否如此之快，并基于时钟使相同的值出现，在这种情况下，有什么方法可以应对这种情况？

Answer 1

将您的变量定义为：

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

如答案Random integer in VB.NET

在循环的不同迭代中生成相同值的随机字符串

Random string generating same values in different iterations of loop

vb.net

random

iis