Regex to strip HTML tags

Question

I have this HTML input:

<font size="5"><p>some text</p>
<p> another text</p></font>

I'd like to use regex to remove the HTML tags so that the output is:

some text
another text

Can anyone suggest how to do this with regex?

Solution 1

You can go with HTML parser called Jericho Html parser.

you can download it from here - http://jericho.htmlparser.net/docs/index.html

Jericho HTML Parser is a java library allowing analysis and manipulation of parts of an HTML document, including server-side tags, while reproducing verbatim any unrecognized or invalid HTML. It also provides high-level HTML form manipulation functions.

The presence of badly formatted HTML does not interfere with the parsing

Solution 2

Since you asked, here's a quick and dirty solution:

String stripped = input.replaceAll("<[^>]*>", "");

(Ideone.com demo)

Using regexps to deal with HTML is a pretty bad idea though. The above hack won't deal with stuff like

• <tag attribute=">">Hello</tag>
• <script>if (a < b) alert('Hello>');</script>

etc.

A better approach would be to use for instance Jsoup. To remove all tags from a string, you can for instance do Jsoup.parse(html).text().

Solution 3

Use a HTML parser. Here's a Jsoup example.

String input = "<font size=\"5\"><p>some text</p>\n<p>another text</p></font>";
String stripped = Jsoup.parse(input).text();
System.out.println(stripped);

Result:

some text another text

Or if you want to preserve newlines:

String input = "<font size=\"5\"><p>some text</p>\n<p>another text</p></font>";
for (String line : input.split("\n")) {
    String stripped = Jsoup.parse(line).text();
    System.out.println(stripped);
}

Result:

some text
another text

Jsoup offers more advantages as well. You could easily extract specific parts of the HTML document using the select() method which accepts jQuery-like CSS selectors. It only requires the document to be semantically well-formed. The presence of the since 1998 deprecated <font> tag is already not a very good indication, but if you know the HTML structure in depth detail beforehand, it'll still be doable.

See also:

• Pros and cons of leading HTML parsers in Java

Solution 4

Starting from aioobe's code, I tried something more daring:

String input = "<font size=\"5\"><p>some text</p>\n<p>another text</p></font>";
String stripped = input.replaceAll("</?(font|p){1}.*?/?>", "");
System.out.println(stripped);

The code to strip every HTML tag would look like this:

public class HtmlSanitizer {

    private static String pattern;

    private final static String [] tagsTab = {"!doctype","a","abbr","acronym","address","applet","area","article","aside","audio","b","base","basefont","bdi","bdo","bgsound","big","blink","blockquote","body","br","button","canvas","caption","center","cite","code","col","colgroup","content","data","datalist","dd","decorator","del","details","dfn","dir","div","dl","dt","element","em","embed","fieldset","figcaption","figure","font","footer","form","frame","frameset","h1","h2","h3","h4","h5","h6","head","header","hgroup","hr","html","i","iframe","img","input","ins","isindex","kbd","keygen","label","legend","li","link","listing","main","map","mark","marquee","menu","menuitem","meta","meter","nav","nobr","noframes","noscript","object","ol","optgroup","option","output","p","param","plaintext","pre","progress","q","rp","rt","ruby","s","samp","script","section","select","shadow","small","source","spacer","span","strike","strong","style","sub","summary","sup","table","tbody","td","template","textarea","tfoot","th","thead","time","title","tr","track","tt","u","ul","var","video","wbr","xmp"};

    static {
        StringBuffer tags = new StringBuffer();
        for (int i=0;i<tagsTab.length;i++) {
            tags.append(tagsTab[i].toLowerCase()).append('|').append(tagsTab[i].toUpperCase());
            if (i<tagsTab.length-1) {
                tags.append('|');
            }
        }
        pattern = "</?("+tags.toString()+"){1}.*?/?>";
    }

    public static String sanitize(String input) {
        return input.replaceAll(pattern, "");
    }

    public final static void main(String[] args) {
        System.out.println(HtmlSanitizer.pattern);

        System.out.println(HtmlSanitizer.sanitize("<font size=\"5\"><p>some text</p><br/> <p>another text</p></font>"));
    }

}

I wrote this in order to be Java 1.4 compliant, for some sad reasons, so feel free to use for each and StringBuilder...

Advantages:

• You can generate lists of tags you want to strip, which means you can keep those you want
• You avoid stripping stuff that isn't an HTML tag
• You keep the whitespaces

Drawbacks:

• You have to list all HTML tags you want to strip from your string. Which can be a lot, for example if you want to strip everything.

If you see any other drawbacks, I would really be glad to know them.

Solution 5

If you use Jericho, then you just have to use something like this:

public String extractAllText(String htmlText){
    Source source = new Source(htmlText);
    return source.getTextExtractor().toString();
}

Of course you can do the same even with an Element:

for (Element link : links) {
  System.out.println(link.getTextExtractor().toString());
}

View more solutions

Comments

[Gumbo]

The > is allowed as a literal character in quoted attribute values.

[ADIT]

Before this tag I hade Head , tilte all those things are there by using above snippet I am getting head,titile text also.i need only this part of text only I tried with

[ADIT]

private static final Pattern BetweenTags = Pattern.compile("<p>([^<]+?)</p>+");

[aioobe]

Ok, if it was something as simple, as stripping tags in uncomplicated HTML, I may have chosen to go with a regexp. In your scenario, I believe that you're better off with a proper parser.

[BjornS]

May I suggest input.replaceAll("<[^>]+>","");

[sproketboy]

Jsoup expects well formed HTML so it's NOT better than Jericho when you are dealing with arbitrary HTML.

[Johncl]

Just a note that using Jsoup actually does not only strips away html tags, it adds spaces as well to separate elements. The text letter count will be greater than that of the html text e.g. written in tinymce editor if that is why you need to strip away the tags.