How to find if String contains html data?

Question

How do I find if a string contains HTML data or not? The user provides input via web interface and it's quite possible he could have used either a simple text or used HTML formatting.

Answer 1

I know this is an old question but I ran into it and was looking for something more comprehensive that could detect things like HTML entities and would ignore other uses of < and > symbols. I came up with the following class that works well.

You can play with it live at http://ideone.com/HakdHo

I also uploaded this to GitHub with a bunch of JUnit tests.

package org.github;  /**  * Detect HTML markup in a string  * This will detect tags or entities  *  * @author [email protected] - David H. Bennett  *  */  import java.util.regex.Pattern;  public class DetectHtml {     // adapted from post by Phil Haack and modified to match better     public final static String tagStart=         "\\<\\w+((\\s+\\w+(\\s*\\=\\s*(?:\".*?\"|'.*?'|[^'\"\\>\\s]+))?)+\\s*|\\s*)\\>";     public final static String tagEnd=         "\\</\\w+\\>";     public final static String tagSelfClosing=         "\\<\\w+((\\s+\\w+(\\s*\\=\\s*(?:\".*?\"|'.*?'|[^'\"\\>\\s]+))?)+\\s*|\\s*)/\\>";     public final static String htmlEntity=         "&[a-zA-Z][a-zA-Z0-9]+;";     public final static Pattern htmlPattern=Pattern.compile(       "("+tagStart+".*"+tagEnd+")|("+tagSelfClosing+")|("+htmlEntity+")",       Pattern.DOTALL     );      /**      * Will return true if s contains HTML markup tags or entities.      *      * @param s String to test      * @return true if string contains HTML      */     public static boolean isHtml(String s) {         boolean ret=false;         if (s != null) {             ret=htmlPattern.matcher(s).find();         }         return ret;     }  } 

Answer 2

You can use regular expressions to search for HTML tags.