Utility methods for dealing with HTML : HTML Parser « Development « Java Tutorial

/* Copyright 2005-2006 Tim Fennell
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *     http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.
// sourceforge stripes

import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.regex.Pattern;

 * Provides simple utility methods for dealing with HTML.
 * @author Tim Fennell
public class HtmlUtil {
    private static final String FIELD_DELIMITER_STRING = "||";
    private static final Pattern FIELD_DELIMITER_PATTERN = Pattern.compile("\\|\\|");

     * Replaces special HTML characters from the set {@literal [<, >, ", ', &]} with their HTML
     * escape codes.  Note that because the escape codes are multi-character that the returned
     * String could be longer than the one passed in.
     * @param fragment a String fragment that might have HTML special characters in it
     * @return the fragment with special characters escaped
    public static String encode(String fragment) {
        // If the input is null, then the output is null
        if (fragment == null) return null;

        StringBuilder builder = new StringBuilder(fragment.length() + 10); // a little wiggle room
        char[] characters = fragment.toCharArray();

        // This loop used to also look for and replace single ticks with &apos; but it
        // turns out that it's not strictly necessary since Stripes uses double-quotes
        // around all form fields, and stupid IE6 will render &apos; verbatim instead
        // of as a single quote.
        for (int i=0; i<characters.length; ++i) {
            switch (characters[i]) {
                case '<'  : builder.append("&lt;"); break;
                case '>'  : builder.append("&gt;"); break;
                case '"'  : builder.append("&quot;"); break;
                case '&'  : builder.append("&amp;"); break;
                default: builder.append(characters[i]);

        return builder.toString();

     * One of a pair of methods (the other is splitValues) that is used to combine several
     * un-encoded values into a single delimited, encoded value for placement into a
     * hidden field.
     * @param values One or more values which are to be combined
     * @return a single HTML-encoded String that contains all the values in such a way that
     *         they can be converted back into a Collection of Strings with splitValues().
    public static String combineValues(Collection<String> values) {
        if (values == null || values.size() == 0) {
            return "";
        else {
            StringBuilder builder = new StringBuilder(values.size() * 30);
            for (String value : values) {
            return encode(builder.toString());

     * Takes in a String produced by combineValues and returns a Collection of values that
     * contains the same values as originally supplied to combineValues.  Note that the order
     * or items in the collection (and indeed the type of Collection used) are not guaranteed
     * to be the same.
     * @param value a String value produced by
     * @return a Collection of zero or more Strings
    public static Collection<String> splitValues(String value) {
        if (value == null || value.length() == 0) {
            return Collections.emptyList();
        else {
            String[] splits = FIELD_DELIMITER_PATTERN.split(value);
            return Arrays.asList(splits);

6.31.HTML Parser
6.31.1.List Tags
6.31.2.html parser DTD
6.31.3.Use javax.swing.text.html.HTMLEditorKit to parse HTML
6.31.4.extends HTMLEditorKit.ParserCallback
6.31.5.Parse HTML
6.31.6.Convert to HTML string
6.31.7.Escape HTML
6.31.8.Filter message string for characters that are sensitive in HTML
6.31.9.Filter the specified message string for characters that are sensitive in HTML
6.31.10.HTML color names
6.31.11.Text To HTML
6.31.12.Unescape HTML
6.31.13.Utility methods for dealing with HTML
6.31.14.insert HTML block dynamically
6.31.15.A collection of all character entites defined in the HTML4 standard.
6.31.16.Decode an HTML color string like '#F567BA;' into a Color