asp.net - VB.NET-ASP.NET-不正确的用户名/密码(验证)

Question

谁能从代码中告诉我代码中有什么问题？

如果用户名和密码不匹配，则lbl文本应显示“用户名/密码错误”。

码:

Protected Sub btnLogin_Click(sender As Object, e As System.EventArgs) Handles btnLogin.Click

        Dim conn As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\Brian\Documents\Visual Studio 2010\WebSites\PetLandia\App_Data\db.mdb")
        Dim cmd As OleDbCommand = New OleDbCommand("SELECT * FROM [User] where Username=? and Password=?", conn)

        cmd.Parameters.AddWithValue("@Username", txtLogin.Text)
        cmd.Parameters.AddWithValue("@Password", txtPassword.Text)




        If (String.IsNullOrEmpty(txtLogin.Text)) Or (String.IsNullOrEmpty(txtPassword.Text)) Then

            lblLoginError.Text = "One or more fields are empty. Please fill in all the fields"
            lblLoginError.Visible = True

        Else

            conn.Open()
            Dim read As OleDbDataReader = cmd.ExecuteReader()

            Try

                If read.HasRows Then

                    While read.Read()

                        If txtLogin.Text = read.Item("username").ToString And txtPassword.Text = read.Item("password").ToString Then


                            Dim tUsername As String = read.Item("Username").ToString

                            Session("Username") = tUsername
                            Response.Redirect("Default.aspx")


                        End If
                    End While
                End If

                read.Close()
            Catch ex As Exception
                Response.Write(ex.Message())
                lblLoginError.Text = "Incorrect Username/Password."
                lblLoginError.Visible = True

            Finally
                conn.Close()
            End Try


        End If

    End Sub

Answer 1

您可以尝试此代码。此代码没有Try Catch块。

    Protected Sub btnLogin_Click(sender As Object, e As System.EventArgs) Handles btnLogin.Click

         If (String.IsNullOrEmpty(txtLogin.Text)) Or (String.IsNullOrEmpty(txtPassword.Text)) Then
            lblLoginError.Text = "One or more fields are empty. Please fill in all the fields"
            lblLoginError.Visible = True

         Else
            Dim conn As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\Brian\Documents\Visual Studio 2010\WebSites\PetLandia\App_Data\db.mdb")
            Dim cmd As OleDbCommand = New OleDbCommand("SELECT * FROM [User] where Username=? and Password=?", conn)
            cmd.Parameters.AddWithValue("@Username", txtLogin.Text)
            cmd.Parameters.AddWithValue("@Password", txtPassword.Text)
            conn.Open()
            Dim read As OleDbDataReader = cmd.ExecuteReader()     
                    If read.HasRows Then
                       read.Read()
                       Session("Username") = read.Item("Username").ToString
                       read.Close()
                       conn.Close() 'Close connection before Redirecting.
                       Response.Redirect("Default.aspx")    
                    Else
                      read.Close()
                      conn.Close()
                      lblLoginError.Text = "Incorrect Username/Password."
                      lblLoginError.Visible = True

                    End If
            End If
        End Sub