MHtmlEncoder.java

/*
 * Copyright 2008-2014 by Emeric Vernat
 *
 *     This file is part of Java Melody.
 *
 * 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.
 */
package net.bull.javamelody.swing.print;

import java.util.Arrays;

/**
 * Encodage de chaines au format HTML.
 *
 * @author Emeric Vernat
 */
final class MHtmlEncoder {
	/**
	 * Liste des caracteres speciaux HTML triée. Remplie dans le init static
	 */
	private static final char[] TO_REPLACE;

	/**
	 * Liste des chaines remplacantes triée dans le même ordre que to_replace. Remplie dans le init static
	 */
	private static final char[][] REPLACE_BY;

	/**
	 * Initialisation de la classe. 1) tri de la liste de caracteres speciaux 2) generation des tables de remplacement
	 *
	 * @formatter:off
	 */
	static {
		// Mapping des caractères spéciaux vers leur code HTML
		// Respecter l'espace entre le caractere et son code.
		final String[] htmlCharacters = {
				"€ €",
				"Œ Œ",
				"œ œ", // latin-15

				// pas de nbsp (insécable à l'impression) "   ",
				"\n <br/>", "\r ", "\t     ",

				"< <", "& &", "Æ Æ", "À À", "Ä Ä", "É É",
				"Ë Ë", "Ì Ì", "Ó Ó", "Ø Ø", "Þ Þ", "Ù Ù",
				"á á", "à à", "ä ä", "ê ê", "ë ë", "ì ì",
				"ó ó", "ø ø", "ß ß", "û û", "ý ý", "¤ ¤",
				"§ §", "ª ª", "­ ­", "° °", "³ ³", "¶ ¶", "¹ ¹",
				"¼ ¼", "¿ ¿", "× ×", "÷ ÷", "¢ ¢", "> >",
				"\" "", "' '", "` '", "Á Á", "Å Å", "Ç Ç",
				"Ê Ê", "Í Í", "Ï Ï", "Ô Ô", "Õ Õ", "Ú Ú",
				"Ü Ü", "â â", "å å", "ç ç", "è è", "í í",
				"ï ï", "ô ô", "õ õ", "þ þ", "ù ù", "ÿ ÿ",
				"¡ ¡", "¥ ¥", "¨ ¨", "« «", "® ®", "± ±",
				"´ ´", "· ·", "º º", "½ ½", "Â Â", "Ã Ã",
				"Ð Ð", "È È", "Î Î", "Ñ Ñ", "Ò Ò", "Ö Ö",
				"Û Û", "Ý Ý", "æ æ", "ã ã", "é é", "ð ð",
				"î î", "ñ ñ", "ò ò", "ö ö", "ú ú", "ü ü",
				"£ £", "¦ ¦", "© ©", "¬ ¬", "¯ ¯", "² ²",
				"µ µ", "¸ ¸", "» »", "¾ ¾",

				"‘ ‘", "’ ’", "‚ ‚", "“ “", "” ”", "„ „",
				"† †", "‡ ‡", "‰ ‰", "‹ ‹", "› ›", "™ ™",
				"– –", "— —", };

		// tri de la table des caracteres HTML
		Arrays.sort(htmlCharacters);
		final int length = htmlCharacters.length;
		TO_REPLACE = new char[length];
		REPLACE_BY = new char[length][];
		for (int i = 0; i < length; i++) {
			// premier caractere dans la table des carateres a remplacer
			TO_REPLACE[i] = htmlCharacters[i].charAt(0);
			// à partir du troisième caractere :
			// dans la table des codes remplacants
			REPLACE_BY[i] = htmlCharacters[i].substring(2).toCharArray();
		}
	}

	/**
	 * Constructeur.
	 */
	private MHtmlEncoder() {
		super();
	}

	/**
	 * Retourne une chaine encodée.
	 *
	 * @return String Chaine encodée
	 * @param s
	 *           String Chaine à encoder
	 */
	public static String encodeString(final String s) {
		if (s != null) {
			final StringBuilder sb = new StringBuilder(s.length() + s.length() / 4);
			encodeString(sb, s);
			return sb.toString();
		}
		return "";
	}

	/**
	 * Append une chaine à un StringBuilder apres l'avoir encodée. Plus la chaine à encoder est longue, plus les gains de perfs sont sensibles.
	 *
	 * @param sb
	 *           String StringBuilder à appender.
	 * @param s
	 *           String Chaine à encoder et à ajouter à <CODE>sb</CODE>
	 */
	public static void encodeString(final StringBuilder sb, final String s) {
		if (s == null) {
			return;
		}
		final int len = s.length();
		// réserve un peu plus de place dans le StringBuilder
		sb.ensureCapacity(sb.length() + len + len / 4);
		int i;
		int index;
		char c;
		for (i = 0; i < len; i++) {
			c = s.charAt(i);
			// petite optimisation (qui represente 90% des cas...)
			if (isSimpleLetterOrDigit(c)) {
				sb.append(c);
			} else {
				// cherche dans le tableau des caractères
				index = Arrays.binarySearch(TO_REPLACE, c);
				if (index >= 0) {
					// si trouvé, append la chaîne remplaçante
					sb.append(REPLACE_BY[index]);
				} else if (c < '\u0020' || c > '\u007e') {
					// si c'est un caractère bizarre non reconnu, on code son numéro décimal (en charset iso-8859-1)
					sb.append("&#").append(Integer.toString(c)).append(';');
				} else {
					// sinon append le caractère sans le modifier
					sb.append(c); // nécessite un charset système genre windows-1252
				}
			}
		}
	}

	private static boolean isSimpleLetterOrDigit(char c) {
		return 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || '0' <= c && c <= '9';
	}
}