如何使Webbrowser控件从vb.net的多行文本框中搜索文本？

Question

我正在尝试开发可以从学术网站搜索批量结果的应用程序或工具。我对所有可以从单行文本框中选择卷号的应用程序进行了编码，并显示了结果。

但是我希望webbrowser控件从多行texbox中选择卷号，逐行，程序应按行数循环，并在完成后将文件保存为pdf。

这是我的代码：

Imports System.Net
Imports System.IO
Imports System.Text
Imports System.Linq
Imports iTextSharp.text.pdf
Imports iTextSharp.text
Imports System.Drawing.Printing
Imports System.Drawing

Public Class Form1

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        batchresults.Show()
        Me.Hide()
    End Sub
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        WebBrowser1.Document.GetElementById("rno").SetAttribute("value", TextBox1.Text)
        If CheckBox1.Checked = True Then
            WebBrowser1.Document.GetElementById("rno").SetAttribute("value", batchresults.TextBox1.Text.ToArray)
        End If
        WebBrowser1.Document.GetElementById("commit").InvokeMember("click")
    End Sub
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Me.Icon = New Icon("result.ico")
        Try
            Using client = New WebClient()
                Using stream = client.OpenRead("http://www.google.com")
                    Timer1.Enabled = True
                    WebBrowser1.Navigate("http://bisesahiwal.edu.pk/allresult/")
                    Button2.Enabled = False
                End Using
            End Using
        Catch
            MsgBox("Connection is not established", MsgBoxStyle.Critical)
            Me.Close()
        End Try
    End Sub
    Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged
        If CheckBox1.Checked = True Then
            TextBox1.Enabled = False
            Button2.Enabled = True
        Else
            TextBox1.Enabled = True
            Button2.Enabled = False
        End If
    End Sub

    Private Sub TextBox1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.Click
        Button2.Enabled = False
        TextBox1.Enabled = True
    End Sub

    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
        WebBrowser1.Document.GetElementById("rno").SetAttribute("value", TextBox1.Text)
    End Sub

    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
        If ComboBox1.Text = "9th" Then
            WebBrowser1.Document.GetElementById("class").SetAttribute("value", "1")
        ElseIf ComboBox1.Text = "10th" Then
            WebBrowser1.Document.GetElementById("class").SetAttribute("value", "2")
        ElseIf ComboBox1.Text = "11th" Then
            WebBrowser1.Document.GetElementById("class").SetAttribute("value", "3")
        ElseIf ComboBox1.Text = "12th" Then
            WebBrowser1.Document.GetElementById("class").SetAttribute("value", "4")
        End If
    End Sub

    Private Sub ComboBox2_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox2.SelectedIndexChanged
        If ComboBox2.Text = "2018" Then
            WebBrowser1.Document.GetElementById("year").SetAttribute("value", "2018")
        ElseIf ComboBox2.Text = "2017" Then
            WebBrowser1.Document.GetElementById("year").SetAttribute("value", "2017")
        ElseIf ComboBox2.Text = "2016" Then
            WebBrowser1.Document.GetElementById("year").SetAttribute("value", "2016")
        ElseIf ComboBox2.Text = "2015" Then
            WebBrowser1.Document.GetElementById("year").SetAttribute("value", "2015")
        ElseIf ComboBox2.Text = "2014" Then
            WebBrowser1.Document.GetElementById("year").SetAttribute("value", "2014")
        ElseIf ComboBox2.Text = "2013" Then
            WebBrowser1.Document.GetElementById("year").SetAttribute("value", "2013")
        ElseIf ComboBox2.Text = "2012" Then
            WebBrowser1.Document.GetElementById("year").SetAttribute("value", "2012")
        End If
    End Sub

    Private Sub ComboBox3_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox3.SelectedIndexChanged
        If ComboBox3.Text = "Annual" Then
            WebBrowser1.Document.GetElementById("sess").SetAttribute("value", "1")
        ElseIf ComboBox3.Text = "Supplementary" Then
            WebBrowser1.Document.GetElementById("sess").SetAttribute("value", "2")
        End If
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        WebBrowser1.Navigate("http://bisesahiwal.edu.pk/allresult/")
    End Sub
    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Label5.Text = batchresults.TextBox1.Lines.Count()
    End Sub
End Class