Java HTML Unescape unescapeHtml(final String input)

Description

Unescapes HTML characters from the input.

License

Apache License

Parameter

Parameter	Description
input	the input

Return

the unescaped html string

Declaration

public static String unescapeHtml(final String input) 

Method Source Code

//package com.java2s;
/*/*  w w  w. ja v a 2 s  .  com*/
 * Copyright 2014 Roque Pinel
 *
 * 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,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

public class Main {
    /**
     * The basic list of HTML escaped characters to be replaced.
     */
    private static final String[][] BASIC_HTML_ESCAPE = { { "\"", "&quot;" }, { "&", "&amp;" }, { "<", "&lt;" },
            { ">", "&gt;" }, };

    /**
     * Unescapes HTML characters from the input.
     * 
     * @param input the input
     * @return the unescaped html string
     */
    public static String unescapeHtml(final String input) {
        String unescapeHexHtmlOutput = unescapeHtmlByNumber(input);
        return unescapeHtmlByName(unescapeHexHtmlOutput);
    }

    /**
     * Unescapes HTML characters based on ASCII numbers.
     * 
     * @param input the input
     * @return
     */
    private static String unescapeHtmlByNumber(final String input) {
        if (input.indexOf("&#") == -1)
            return input;

        String out = "";

        for (int i = 0, length = input.length(); i < length; i++) {
            if (input.charAt(i) == '&' && i + 1 < length && input.charAt(i + 1) == '#') {
                int j = i + 2;
                boolean isValid = true;
                int n = 0;
                for (; j < length; j++) {
                    char c = input.charAt(j);
                    if (c == ';')
                        break;
                    else if (c >= '0' || c <= '9') {
                        n = n * 10 + (c - '0');
                    } else {
                        isValid = false;
                        break;
                    }
                }
                if (isValid && n != 0) {
                    char unescape = (char) n;
                    out += unescape;
                    i = j;
                } else {
                    out += input.charAt(i);
                }
            } else {
                out += input.charAt(i);
            }
        }

        return out;
    }

    /**
     * Unescapes HTML characters based on it name (value).
     * 
     * @param input the input
     * @return
     */
    private static String unescapeHtmlByName(final String input) {
        String result = input;

        for (int i = 0; i < BASIC_HTML_ESCAPE.length; i++) {
            result = replace(result, BASIC_HTML_ESCAPE[i][1], BASIC_HTML_ESCAPE[i][0]);
        }

        return result;
    }

    /**
     * Replaces the pattern occurrences from the input with the replacement string.
     * 
     * @param input the input
     * @param pattern the pattern
     * @param replacement the replacement
     * @return
     */
    public static String replace(String input, String pattern, String replacement) {
        String out = "";

        int n = input.length();
        int m = pattern.length();
        int lastFound = -1;

        for (int i = 0; i < n;) {
            if (i + m >= n) {
                out += input.substring(lastFound == -1 ? 0 : i, n);
                break;
            }

            boolean hasMatched = true;
            for (int j = 0; j < m; j++) {
                if (pattern.charAt(j) != input.charAt(i + j)) {
                    hasMatched = false;
                    break;
                }
            }

            if (hasMatched) {
                if (lastFound == -1 && i > 0)
                    out += input.substring(0, i);
                else if (lastFound + m < i)
                    out += input.substring(lastFound + m, i);
                out += replacement;
                lastFound = i;
                i += m;
            } else {
                i++;
            }
        }

        return out;
    }
}

Related

1. htmlUnescape(String s)
2. htmlUnescape(String source)
3. unEscapeHTML(final String escapedHTML)
4. unescapeHTML(String comment)
5. unescapeHTML(String html)
6. unescapeHtml(String s)
7. unescapeHtml(String s)