vb.net如何判断网站页面是否存在？

[mythhack]

vb.net 判断网页返回值
可以通过判断http头来判断吗？
如果网站页面为404则执行..
如果网站页面为200则..
就是不明白vb.net应该怎么判断http头这些希望解答

[孟子E章]

判断网络地址 Url 是否存在的方法

http://dotnet.aspx.cc/file/Delect-Url-Exists.aspx

你转成VB.NET就可以了，网上有免费的工具
http://www.developerfusion.com/tools/convert/csharp-to-vb/

[mythhack]

[Quote=引用 1 楼 net_lover 的回复:]
判断网络地址 Url 是否存在的方法

http://dotnet.aspx.cc/file/Delect-Url-Exists.aspx

你转成VB.NET就可以了，网上有免费的工具
http://www.developerfusion.com/tools/convert/csharp-to-vb/
[/Quote]
转换完会提示
未声明“Response”。它可能因其保护级别而不可访问。

[xrongzhen]

Private Function UrlIsExist(url As [String]) As Boolean
	Dim u As System.Uri = Nothing
	Try
		u = New Uri(url)
	Catch
		Return False
	End Try
	Dim isExist As Boolean = False
	Dim r As System.Net.HttpWebRequest = TryCast(System.Net.HttpWebRequest.Create(u), System.Net.HttpWebRequest)
	r.Method = "HEAD"
	Try
		Dim s As System.Net.HttpWebResponse = TryCast(r.GetResponse(), System.Net.HttpWebResponse)
		If s.StatusCode = System.Net.HttpStatusCode.OK Then
			isExist = True
		End If
	Catch x As System.Net.WebException
		Try
			isExist = (TryCast(x.Response, System.Net.HttpWebResponse).StatusCode <> System.Net.HttpStatusCode.NotFound)
		Catch
			isExist = (x.Status = System.Net.WebExceptionStatus.Success)
		End Try
	End Try
	Return isExist
End Function
Protected Sub Page_Load(sender As Object, e As EventArgs)
	Response.Write("<li>http://dotnet.aspx.cc/Images/ 是否存在：" & UrlIsExist("http://dotnet.aspx.cc/Images/"))
	Response.Write("<li>http://dotnet.aspx.cc/ImagesX/ 是否存在：" & UrlIsExist("http://dotnet.aspx.cc/ImagesX/"))
	Response.Write("<li>http://xxxxx/ 是否存在：" & UrlIsExist("http://xxxxx/"))
	Response.Write("<li>hxxxxxxxxxxxxxxxxxxx 是否存在：" & UrlIsExist("hxxxxxxxxxxxxxxxxxxx"))

	Response.Write("<li>http://dotnet.aspx.cc/Images/logoSite.gif 是否存在：" & UrlIsExist("http://dotnet.aspx.cc/Images/logoSite.gif"))

	Response.Write("<li>http://dotnet.aspx.cc/Images/logoSite2.gif 是否存在：" & UrlIsExist("http://dotnet.aspx.cc/Images/logoSite2.gif"))
End Sub

那一句报的错？？

[mythhack]

[Quote=引用 3 楼 xrongzhen 的回复:]
VB.NET code

Private Function UrlIsExist(url As [String]) As Boolean
Dim u As System.Uri = Nothing
Try
u = New Uri(url)
Catch
Return False
End Try
Dim isEx……
[/Quote]
Response.Write("<li>http://dotnet.aspx.cc/Images/ 是否存在：" & UrlIsExist("http://dotnet.aspx.cc/Images/"))
Response.Write("<li>http://dotnet.aspx.cc/ImagesX/ 是否存在：" & UrlIsExist("http://dotnet.aspx.cc/ImagesX/"))
Response.Write("<li>http://xxxxx/ 是否存在：" & UrlIsExist("http://xxxxx/"))
Response.Write("<li>hxxxxxxxxxxxxxxxxxxx 是否存在：" & UrlIsExist("hxxxxxxxxxxxxxxxxxxx"))

Response.Write("<li>http://dotnet.aspx.cc/Images/logoSite.gif 是否存在：" & UrlIsExist("http://dotnet.aspx.cc/Images/logoSite.gif"))

Response.Write("<li>http://dotnet.aspx.cc/Images/logoSite2.gif 是否存在：" & UrlIsExist("http://dotnet.aspx.cc/Images/logoSite2.gif"))
End Sub

[mythhack]

会提示未声明“Response”。它可能因其保护级别而不可访问

[mythhack]

..解决了我没加载出错的那些 但是UrlIsExist这个函数可以判断网页返回值吗？

[wuyq11]

Dim html As String = ""
Dim request As HttpWebRequest = DirectCast(WebRequest.Create("域名"), HttpWebRequest)
request.Accept = "*/*"
Dim response As HttpWebResponse = Nothing
Dim stream As Stream = Nothing
Dim reader As StreamReader = Nothing
Try
response = DirectCast(request.GetResponse(), HttpWebResponse)
'读取不到发生异常，就是访问不到
Catch excpt As Exception
End Try

Try
Dim client As New WebClient()
Dim buffer As Byte() = client.DownloadData(url)
Catch generatedExceptionName As Exception
isConnect = False
End Try
Try
Dim request As HttpWebRequest = DirectCast(WebRequest.Create(""), HttpWebRequest)
Dim myResponse As HttpWebResponse = DirectCast(request.GetResponse(), HttpWebResponse)

If myResponse.StatusDescription.ToString().ToUpper() = "" Then
End If
Catch webExcp As WebException
End Try