如何从网页中找到的不完整 URL 形成完整 URL？

Question

我可以检索网页的文本，假设 https://stackoverflow.com/questions 带有一些真实的和虚构的链接

    /questions
    /tags
    /questions?sort=votes
    /questions?sort=active
    randompage.aspx
    ../coolhomepage.aspx

：我的原始页面是 https://stackoverflow.com/questions .Net 中有没有办法解决此链接？

    https://stackoverflow.com/questions
    https://stackoverflow.com/tags
    https://stackoverflow.com/questions?sort=votes
    https://stackoverflow.com/questions?sort=active
    https://stackoverflow.com/questions/randompage.aspx
    https://stackoverflow.com/coolhomepage.aspx

有点像浏览器足够智能来解析链接的方式。

============================= 更新 - 使用大卫的解决方案：

    'Regex to match all <a ... /a> links
    Dim myRegEx As New Regex("\<\s*a                   (?# Find opening <a tag)           " & _
                             ".+?href\s*=\s*['""]      (?# Then all to href=' or "" )     " & _
                             "(?<href>.*?)['""]        (?# Then all to the next ' or "" ) " & _
                             ".*?\>                    (?# Then all to > )                " & _
                             "(?<name>.*?)\<\s*/a\s*\> (?# Then all to </a> )             ", _
                             RegexOptions.IgnoreCase Or _
                             RegexOptions.IgnorePatternWhitespace Or _
                             RegexOptions.Multiline)

    'MatchCollection to hold all the links that are matched
    Dim myMatchCollection As MatchCollection
    myMatchCollection = myRegEx.Matches(Me._RawPageText)

    'Loop through all matches and evaluate the value of the href attribute.
    For i As Integer = 0 To myMatchCollection.Count - 1
        Dim thisLink As String = ""
        thisLink = myMatchCollection(i).Groups("href").Value()
        'This checks for Javascript and Mailto links.
        'This is not complete. There are others to check I just haven't encountered them yet.
        If thisLink.ToLower.StartsWith("javascript") Then
            thisLink = "JAVASCRIPT: " & thisLink
        ElseIf thisLink.ToLower.StartsWith("mailto") Then
            thisLink = "MAILTO: " & thisLink
        Else
            Dim baseUri As New Uri(Me.URL)

            If Not thisLink.ToLower.StartsWith("http") Then
                'This is a partial URL so we will assume that it's relative to our originating URL
                Dim myUri As New Uri(baseUri, thisLink)
                thisLink = "RELATIVE LOCAL LINK: RESOLVED: " & myUri.ToString() & " ORIGINAL: " & thisLink
            Else
                'The link starts with HTTP, determine if part of base host or is outside host.
                Dim ThisUri As New Uri(thisLink)
                If ThisUri.Host.ToLower = baseUri.Host.ToLower Then
                    thisLink = "INSIDE COMPLETE LINK: " & thisLink
                Else
                    thisLink = "OUTSIDE LINK: " & thisLink
                End If
            End If

        End If

        'I'm storing the found links into a Generic.List(Of String)
        'This link has descriptive text added to it.
        'TODO: Make collection to hold only unique internal links.
        Me._Links.Add(thisLink)
    Next

Answer 1

你的意思是这样吗？

Uri baseUri = new Uri("http://www.contoso.com");
Uri myUri = new Uri(baseUri, "catalog/shownew.htm");

Console.WriteLine(myUri.ToString());

示例来自 http://msdn.microsoft.com/en-us/library /9hst1w91.aspx

Answer 2

如果您指的是服务器端，则可以使用 ResolveUrl()：

string url = ResolveUrl("~/questions");

Answer 3

我不明白你在这种情况下的“解决”是什么意思，但你可以尝试插入一个基本的 html 元素。 既然您问浏览器将如何处理它。

“ 标记指定页面上所有链接的默认地址或默认目标。”

http://www.w3schools.com/TAGS/tag_base.asp