com.jwebmp.core.utilities.EscapeChars.java Source code

Introduction

Here is the source code for com.jwebmp.core.utilities.EscapeChars.java

Source

/*
 * Copyright (C) 2017 GedMarc
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.jwebmp.core.utilities;

import org.apache.commons.text.StringEscapeUtils;

import javax.validation.constraints.NotNull;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
import java.util.Arrays;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Convenience methods for escaping special characters related to HTML, XML, and regular expressions.
 * <p>
 * <p>
 */
public class EscapeChars {

    private static final Pattern SCRIPT = Pattern.compile("<SCRIPT>", Pattern.CASE_INSENSITIVE);
    private static final Pattern SCRIPT_END = Pattern.compile("</SCRIPT>", Pattern.CASE_INSENSITIVE);

    private static final Character[] EscapeRegexCharsetRaw = new Character[] { StaticStrings.CHAR_DOT, '\\', '?',
            '*', '+', '&', ':', '{', '}', '[', ']', '(', ')', '^', '$' };
    private static final List<Character> EscapeRegexCharset = Arrays.asList(EscapeChars.EscapeRegexCharsetRaw);

    /**
     * Static only
     */
    private EscapeChars() {
        //empty - prevent construction
    }

    /**
     * Escape characters for text appearing in HTML markup.
     * <p>
     * &lt;P&gt;This method exists as a defence against Cross Site Scripting (XSS) hacks. The idea is to neutralize control characters commonly used by scripts, such that they will
     * not be executed by
     * the browser. This is done by replacing the control characters with their escaped equivalents. See {link hirondelle.web4j.security.SafeText} as well.
     *
     * @param input
     *
     * @return
     */
    public static String forHTML(String input) {
        return StringEscapeUtils.escapeHtml4(input);
    }

    /**
     * Escape all ampersand characters in a URL.
     *
     * @param input
     *
     * @return
     */
    public static String forHrefAmpersand(String input) {
        return input.replace("&", StaticStrings.HTML_AMPERSAND);
    }

    /**
     * Formats as UTF-8
     *
     * @param aURLFragment
     *
     * @return
     *
     * @throws java.io.UnsupportedEncodingException
     */
    @NotNull
    public static String forURL(String aURLFragment) throws UnsupportedEncodingException {
        String result = "";
        try {
            result = URLEncoder.encode(aURLFragment, "UTF-8");
        } catch (UnsupportedEncodingException ex) {
            throw ex;
        }
        return result;
    }

    /**
     * Escape characters for text appearing as XML data, between tags.
     *
     * @param aText
     *
     * @return
     */
    public static String forXML(String aText) {
        return StringEscapeUtils.escapeXml11(aText);
    }

    /**
     * Escapes characters for text appearing as data in the
     *
     * @param input
     *
     * @return
     */
    public static String forJSON(String input) {
        return StringEscapeUtils.escapeJson(input);
    }

    /**
     * Returns opening and closing tags replaced with the HTML Equivalents replaced by their escaped equivalents.
     *
     * @param aText
     *
     * @return
     */
    public static String disableTags(String aText) {
        StringBuilder result = new StringBuilder();
        StringCharacterIterator iterator = new StringCharacterIterator(aText);
        char character = iterator.current();
        while (character != CharacterIterator.DONE) {
            switch (character) {
            case '<':
                result.append("&lt;");
                break;
            case '>':
                result.append("&gt;");
                break;
            default:
                //the char is not a special one
                //add it to the result as is
                result.append(character);
                break;
            }
            character = iterator.next();
        }
        return result.toString();
    }

    /**
     * Replace characters having special meaning in regular expressions with their escaped equivalents, preceded by a '\' character.
     *
     * @param aRegexFragment
     *
     * @return
     */
    public static String forRegex(String aRegexFragment) {
        StringBuilder result = new StringBuilder();
        StringCharacterIterator iterator = new StringCharacterIterator(aRegexFragment);
        char character = iterator.current();
        while (character != CharacterIterator.DONE) {
            if (EscapeChars.EscapeRegexCharset.contains(character)) {
                result.append('\\' + character);
            } else {
                result.append(character);
            }
            character = iterator.next();
        }
        return result.toString();
    }

    /**
     * Escape <tt>'$'</tt> and <tt>'\'</tt> characters in replacement strings.
     *
     * @param input
     *
     * @return
     */
    public static String forReplacementString(String input) {
        return Matcher.quoteReplacement(input);
    }

    /**
     * Disable all script tags
     *
     * @param aText
     *
     * @return
     */
    public static String forScriptTagsOnly(String aText) {
        String result;
        Matcher matcher = EscapeChars.SCRIPT.matcher(aText);
        result = matcher.replaceAll("&gt;SCRIPT&lt;");
        matcher = EscapeChars.SCRIPT_END.matcher(result);
        result = matcher.replaceAll("&gt;/SCRIPT&lt;");
        return result;
    }

    /**
     * Adds padding to string builder
     *
     * @param index
     * @param stringBuilder
     */
    public static void addCharEntity(Integer index, StringBuilder stringBuilder) {
        String padding = "";
        if (index <= 9) {
            padding = "00";
        } else if (index <= 99) {
            padding = "0";
        } else {
            //no prefix
        }
        String number = padding + index.toString();
        stringBuilder.append("&#").append(number).append(";");
    }
}