vb.net - 如何使 Vb.Net 登录表单允许多个用户使用存储在 .DAT 文件中的密码登录

Question

我有一个用 VB 2008 设计的登录表单。用户可以通过从组合框中的下拉列表中选择管理员或访客来登录。然后输入一个密码，该密码必须与存储在 .DAT 文件中的相应用户名的密码匹配。 显示存储在 .DAT 文件中的用户名和密码的屏幕截图

文件上的第二个用户名 Guest 和密码“passwordG”正在工作，而第一个用户名 Admin 和密码“passwordG”不起作用。

Public Class frmlogin
Dim user_name As String
Dim pass_word As String
Dim counter As Byte
Dim attempts As Integer = 0

Private Sub login_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    cmbUsername.Items.Add("Admin")
    cmbUsername.Items.Add("Guest")
    FileOpen(1, My.Application.Info.DirectoryPath & "\users.DAT", OpenMode.Input)
    Do Until EOF(1)
        Input(1, user_name)
        Input(1, pass_word)
    Loop
    FileClose(1)

请我需要有关如何使这项工作的帮助。那如何使程序接受密码。代码是否不正确或不充分或密码未正确存储在 .DAT 文件中？拜托我需要你的帮忙。谢谢你。

标签： vb.net

Answer 1

只需使用纯文本文件。否则，我们将不得不去掉引号。

Admin,passwordA
Guest,passwordG

由于我关闭了登录表单，请确保关闭的应用程序属性设置如下：

Private GuestPassword As String
Private AdminPassword As String

Private Sub login_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    'Fill the combo box
    cmbUsername.Items.Add("Admin")
    cmbUsername.Items.Add("Guest")
    'one of the .net methods to read a file, returns an array of lines in the file
    Dim lines = File.ReadAllLines("user.txt")
    'Split by the comma, the first line into and array
    Dim splits = lines(0).Split(","c)
    'The second element of this array holds the Admin password
    AdminPassword = splits(1)
    splits = lines(1).Split(","c)
    GuestPassword = splits(1)
End Sub

Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click
    If cmbUserName.Text = "Admin" AndAlso AdminPassword = txtPassword.Text Then
        'Show the Admin form
    ElseIf cmbUserName.Text = "Guest" AndAlso GuestPassword = txtPassword.Text Then
        'Show the guest form
    Else
        MessageBox.Show("Sorry, no match")
    End If
    Me.Close()
End Sub

编辑

我们将使用 aDictionary将用户存储在内存中。这提供了非常快速的查找。

字典包含键/值对。请注意，在表单加载中，我们将Dictionary密码填写为Key，用户类型填写为Value.

对空格要非常小心。文本文件或文本框中不应有任何内容。您可能需要添加.Trim以作为预防措施。

在按钮单击中，我们userType通过搜索用户提供的密钥来检索。这被一个Try块包围，因为如果找不到密钥，则会引发异常。

Private UsersDictionary As New Dictionary(Of String, String)

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Dim lines = File.ReadAllLines("users.txt")
    For Each line In lines
        Dim splits = line.Split(","c)
        UsersDictionary.Add(splits(1), splits(0))
    Next
End Sub

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim userType As String
    Try
        userType = UsersDictionary.Item(TextBox1.Text)
    Catch ex As System.Collections.Generic.KeyNotFoundException
        MessageBox.Show("Sorry, you are not a registered user.")
        Exit Sub
    End Try
    If userType = "Admin" Then
        'open the admin form
    Else
        'open the user form
    End If
    Me.Close()
End Sub