How can remove the comments and contents of the comments from an html file using Java where the comments are written like:
<!--
Any idea or help needed on this.
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This question should be named "How to remove comments from HTML using Java"Sergio del Amo– Sergio del Amo2009-05-26 11:52:32 +00:00Commented May 26, 2009 at 11:52
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3 Answers
Take a look at JTidy, the java port of HTML Tidy. You could override the print methods of the PPrint object to ignore the comment tags.
Comments
If you don't have valid xhtml, which a comment posted reminded me of, you should at first apply jtidy to tidy up the html and make it valid xhtml.
See this for example code on jtidy.
Then I'd convert the html to a DOM instance.
Like so:
final DocumentBuilderFactory newFactory = DocumentBuilderFactory.newInstance();
final DocumentBuilder documentBuilder = newFactory.newDocumentBuilder();
Document document = documentBuilder.parse( new InputSource( new StringReader( string ) ) );
Then I'd navigate through the document tree and modify nodes as needed.
1 Comment
Joachim Sauer
Most HTML around is still not XHTML, so JTidy should probably be the first option, not an afterthought.
try a simple regex like
String commentless = pageString.replaceAll("<!--[\w\W]*?-->", "");
edit: to explain the regex:
<!--matches the literal comment start[\w\W]matches every character (even newlines) which will be inside the comment*?matches multiple of the 'any character' but matches the smallest amount possible (not greedy)-->closes the comment
9 Comments
Simon Groenewolt
A simple regex should be able to do the job - but this one doesn't ... comments are not always opened and closed on the same line. I just found this link on google that seems better: ostermiller.org/findhtmlcomment.html
cobbal
if you try this, it works. the \w\W catches everything, including newlines, unlike '.'
Peter Štibraný
No, it isn't. It would remove "comment" from this too: <input type="text" value="<!-- Hello world -->">, which would be incorrect. <!-- doesn't always start the comment.
cobbal
good point. is it legal to have < in a string? I'm fairly sure > will throw most browsers.
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