vb.net 如何在 ASP.NET 中使用 Request.UrlReferrer？
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How to use Request.UrlReferrer in ASP.NET?
提问by user3724490
I have two aspx web pages. In the first one I have this code:
我有两个 aspx 网页。在第一个我有这个代码：
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Response.Redirect("~/Code.aspx")
End Sub
Now in the Code.aspx page I have this code:
现在在 Code.aspx 页面中，我有以下代码：
Label1.Text = Request.UrlReferrer.ToString
I want the label show the first page URl, but there is a runtime ERROR.How to fix this? thanks
我希望标签显示第一页 URl，但有一个运行时错误。如何解决这个问题？谢谢
This is the error message: Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
这是错误消息： Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
回答by Full Time Skeleton
Take the redirect out of the page load and put it on a link or something other than a response.redirect. Then try something like this in your code to make sure it's not null:
从页面加载中取出重定向并将其放在链接或 response.redirect 以外的其他内容上。然后在你的代码中尝试这样的事情以确保它不为空：
if(Request.UrlReferrer != null)
{
Label1.Text = Request.UrlReferrer.ToString();
}
else
{
Label1.Text = "No URL referrer";
}
Sorry just noticed you're using VB.net, the code is easy enough to change though and the theory is the same.
抱歉，刚刚注意到您正在使用 VB.net，但代码很容易更改，而且原理是相同的。
If you require the response.redirect I suppose a cookie based solution would work but seems a little involved for such a basic requirement.
如果您需要 response.redirect 我想基于 cookie 的解决方案会起作用，但似乎有点涉及这样的基本要求。
