将相对网址替换为绝对网址 [英] Replace relative urls to absolute
问题描述
我有一个字符串形式的页面html源：
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>
我想将所有相对路径都转换为绝对路径。我希望输出为：
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>
注意：我只希望在该 string 。该字符串中已经存在的绝对值不应该被触及，它们对我来说很好，因为它们已经是绝对值了。
可以通过正则表达式或其他方式吗？
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?
推荐答案
不要尝试使用以下方式解析html：正则表达式，如 https://stackoverflow.com/a/1732454/932418 和https://stackoverflow.com/a/1758162/932418
使用像 HtmlAgilityPack 之类的html解析器
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();
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