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问题:
I have the html source of a page in a form of string with me:
<html>
<head>
<link rel="stylesheet" type="text/css" href="/css/all.css" />
</head>
<body>
<a href="/test.aspx">Test</a>
<a href="http://mysite.com">Test</a>
<img src="/images/test.jpg"/>
<img src="http://mysite.com/images/test.jpg"/>
</body>
</html>
I want to convert all the relative paths to absolute. I want the output be:
<html>
<head>
<link rel="stylesheet" type="text/css" href="http://mysite.com/css/all.css" />
</head>
<body>
<a href="http://mysite.com/test.aspx">Test</a>
<a href="http://mysite.com">Test</a>
<img src="http://mysite.com/images/test.jpg"/>
<img src="http://mysite.com/images/test.jpg"/>
</body>
</html>
Note: I want only the relative paths to be converted to absolute ones in that string. The absolute ones which are already in that string should not be touched, they are fine to me as they are already absolute.
Can this be done by regex or other means?
回答1:
Don't try to parse html with regex as expained here https://stackoverflow.com/a/1732454/932418 and https://stackoverflow.com/a/1758162/932418
Use an html parser like HtmlAgilityPack instead
string html =
@"<html>
<head>
<link rel=""stylesheet"" type=""text/css"" href=""/css/all.css"" />
</head>
<body>
<a href=""/test.aspx"">Test</a>
<a href=""http://example.com"">Test</a>
<img src=""/images/test.jpg""/>
<img src=""http://example.com/images/test.jpg""/>
</body>
</html>";
StringWriter writer = new StringWriter();
string baseUrl= "http://example.com";
HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();
doc.LoadHtml(html);
foreach(var img in doc.DocumentNode.Descendants("img"))
{
img.Attributes["src"].Value = new Uri(new Uri(baseUrl), img.Attributes["src"].Value).AbsoluteUri;
}
foreach (var a in doc.DocumentNode.Descendants("a"))
{
a.Attributes["href"].Value = new Uri(new Uri(baseUrl), a.Attributes["href"].Value).AbsoluteUri;
}
doc.Save(writer);
string newHtml = writer.ToString();
回答2:
Add
<base href="http://mysite.com/images/" />
To the head of the page
回答3:
Use regular expressions for this. Here is short example
static void Main(string[] args)
{
string input = "<html>\n<head>\n<link rel=\"stylesheet\" type=\"text/css\" href=\"/css/all.css\" /> \n</head>\n<body>\n<a href=\"/test.aspx\">Test</a>\n<a href=\"http://mysite.com\">Test</a>\n<img src=\"/images/test.jpg\"/>\n<img src=\"http://mysite.com/images/test.jpg\"/>\n</body>\n</html>";
string pattern = "((?:src|href)[\\s]*?)(?:\\=[\\s]*?[\\\"\\\'])[\\/*\\\\*]?(?!..+[s]?\\:[\\/]*)(.*?)(?:[\\s\\\"\\\'])";
var reg = new Regex(pattern, RegexOptions.IgnoreCase);
string prefix = @"http://mysite.com";
var result = reg.Replace(input, "$1=\""+prefix+"$2\"");
}
the result is
<html>
<head>
<link rel="stylesheet" type="text/css" href="http://mysite.com/css/all.css" />
</head>
<body>
<a href="http://mysite.com/test.aspx">Test</a>
<a href="http://mysite.com">Test</a>
<img src="http://mysite.com/images/test.jpg"/>
<img src="http://mysite.com/images/test.jpg"/>
</body>
</html>
回答4:
Check this out, it could help you.
It is in the following format: http(s)://domain(:port)/AppPath)
HttpContext.Current.Request.Url.Scheme + "://" + HttpContext.Current.Request.Url.Authority + HttpContext.Current.Request.ApplicationPath;
Or you could use:
Page.ResolveUrl("img/youFile");
回答5:
Look at this function:
Private Function ConvertALLrelativeLinksToAbsoluteUri(ByVal html As String, ByVal PageURL As String)
Dim result As String = Nothing
' Getting all Href
Dim opt As New RegexOptions
Dim XpHref As New Regex("(href="".*?"")", RegexOptions.IgnoreCase)
Dim i As Integer
Dim NewSTR As String = html
For i = 0 To XpHref.Matches(html).Count - 1
Application.DoEvents()
Dim Oldurl As String = Nothing
Dim OldHREF As String = Nothing
Dim MainURL As New Uri(PageURL)
OldHREF = XpHref.Matches(html).Item(i).Value
Oldurl = OldHREF.Replace("href=", "").Replace("HREF=", "").Replace("""", "")
Dim NEWURL As New Uri(MainURL, Oldurl)
Dim NewHREF As String = "href=""" & NEWURL.AbsoluteUri & """"
NewSTR = NewSTR.Replace(OldHREF, NewHREF)
Next
html = NewSTR
Dim XpSRC As New Regex("(src="".*?"")", RegexOptions.IgnoreCase)
For i = 0 To XpSRC.Matches(html).Count - 1
Application.DoEvents()
Dim Oldurl As String = Nothing
Dim OldHREF As String = Nothing
Dim MainURL As New Uri(PageURL)
OldHREF = XpSRC.Matches(html).Item(i).Value
Oldurl = OldHREF.Replace("src=", "").Replace("src=", "").Replace("""", "")
Dim NEWURL As New Uri(MainURL, Oldurl)
Dim NewHREF As String = "src=""" & NEWURL.AbsoluteUri & """"
NewSTR = NewSTR.Replace(OldHREF, NewHREF)
Next
Return NewSTR
End Function
回答6:
This works great for me. I uses it on email templates. I'm using the MVC/Razor "~/" at the beginning of each link.
' Parse HTML and make relative links absolute with p_basepath
Public Function ParseHTMLLinks(ByVal MailBodyHTML As String) As String
' Declare & intialize variables
Dim strHTMLBody As String = MailBodyHTML
' Set regex variables
Dim strSrcSubMatch As String = ""
Dim strSrcFullUrl As String = ""
Dim srcPattern As String = "[=""]\/?([^""\s]*(\.gif|\.jpg|\.jpeg|\.png|\.css|\.js))[""\s]"
Dim srcOptions As RegexOptions = RegexOptions.IgnoreCase
Dim regex As Regex = New Regex(srcPattern, srcOptions)
Dim regexSub As Regex = New Regex(srcPattern, srcOptions)
Dim Matches As MatchCollection = regex.Matches(strHTMLBody)
Try
For Each Match As Match In Matches
' filter out absolute links
If InStr(Match.ToString, "://") = 0 And InStr(LCase(Match.ToString), "mailto:") = 0 And InStr(LCase(Match.ToString), "javascript:") = 0 Then
' Remove the " at each end of relative path
strSrcSubMatch = regexSub.Replace(Match.ToString, "$1")
' Concatenate the FullPath
strSrcFullUrl = p_basePath & strSrcSubMatch
' Execute the replace
strHTMLBody = Replace(strHTMLBody, "/" & strSrcSubMatch, strSrcFullUrl)
End If
Next
Catch e As WebException
'Add errors to List(Of WebException), if any.
ErrorCodes.Add(e)
End Try
Return strHTMLBody 'MailBodyHTML
End Function
