对象引用未设置为对象的实例(自动登录错误) [英] Object reference not set to an instance of an object ( Auto Login Error)

问题描述

你能帮我吗?我试图在自己的论坛中制作用于自动登录的小型软件，但出现此错误对象引用未设置为对象的实例".我认为问题在于我的论坛使用了不同的脚本，例如phpbb和smf，如果我可以登录这两个论坛之一，我会很高兴，因为我有超过15个论坛.这是代码，对于我的英语不好，我感到抱歉:

Can you help me? I trying to make a small software for autologin in my own forums but I get this error "Object reference not set to an instance of an object" . I think that the problem is that I have forums with diferent script like phpbb and smf , I will be happy if I can login in one of both because I have more than 15 forums.This is the code and sorry for my bad english:

Public Class Form1

    Private Sub WebBrowser1_DocumentCompleted(ByVal sender As System.Object, ByVal e As WebBrowserDocumentCompletedEventArgs) Handles WebBrowser1.DocumentCompleted

    End Sub

    Private Sub WebBrowser1_ProgressChanged(ByVal sender As Object, ByVal e As WebBrowserProgressChangedEventArgs) Handles WebBrowser1.ProgressChanged
        ProgressBar1.Maximum = e.MaximumProgress
        ProgressBar1.Value = e.CurrentProgress

    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) Handles MyBase.Load
        WebBrowser1.Navigate(TextBox1.Text)
    End Sub

    Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As EventArgs) Handles Timer1.Tick
        If ProgressBar1.Value = ProgressBar1.Maximum Then
            WebBrowser1.Document.GetElementById("user").SetAttribute("value", user.Text)
            WebBrowser1.Document.GetElementById("password").SetAttribute("value", password.Text)
            WebBrowser1.Document.GetElementById("login_button").InvokeMember("click")
        End If
    End Sub
End Class

推荐答案

您没有告诉我们发生异常的位置.

我要猜测并说它在这里:

You didn''t tell us WHERE the exception is occurring.

I''m going to guess and say that it''s here:

WebBrowser1.Document.GetElementById("user").SetAttribute("value", user.Text)

改为这样:

Do it this way instead:

Dim element As HtmlElement = WebBrowser1.Document.GetElementById("user")
If (element IsNot Nothing) Then
    element.SetAttributes("value", user.Text)
End If

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