¿Cómo puedo eliminar el escape de entidades de caracteres HTML en Java?
Básicamente, me gustaría decodificar un documento HTML determinado y reemplazar todos los caracteres especiales, como " "→ " "y ">"→ ">".
En .NET , podemos utilizar el método HttpUtility.HtmlDecode .
¿Cuál es la función equivalente en Java?
Aceptado
He usado Apache Commons StringEscapeUtils.unescapeHtml4() para esto:
Elimina el escape de una cadena que contiene escapes de entidad a una cadena que contiene los caracteres Unicode reales correspondientes a los escapes. Admite entidades HTML 4.0.
Las bibliotecas mencionadas en otras respuestas serían buenas soluciones, pero si ya está investigando contenido HTML del mundo real en su proyecto, el Jsoupproyecto tiene mucho más que ofrecer que simplemente administrar cosas de "ampersand libra FFFF punto y coma" .
// textValue: <p>This is a sample. \"Granny\" Smith –.<\/p>\r\n
// becomes this: This is a sample. "Granny" Smith –.
// with one line of code:
// Jsoup.parse(textValue).getText(); // for older versions of Jsoup
Jsoup.parse(textValue).text();
// Another possibility may be the static unescapeEntities method:
boolean strictMode = true;
String unescapedString = org.jsoup.parser.Parser.unescapeEntities(textValue, strictMode);
Y también obtiene la API conveniente para extraer y manipular datos, utilizando lo mejor de los métodos similares a DOM, CSS y jQuery . Es de código abierto y licencia MIT .
Probé Apache Commons ' StringEscapeUtils.unescapeHtml3() en mi proyecto, pero no quedé satisfecho con su rendimiento. Resulta que realiza muchas operaciones innecesarias. Por un lado, asigna un StringWriter para cada llamada, incluso si no hay nada que eliminar en la cadena. Reescribí ese código de manera diferente y ahora funciona mucho más rápido.
El siguiente código elimina todos los símbolos HTML 3 y los escapes numéricos (equivalente a Apache unescapeHtml3 ). Puede agregar más entradas al mapa si necesita HTML 4 .
package com.example;
import java.io.StringWriter;
import java.util.HashMap;
public class StringUtils {
public static final String unescapeHtml3(final String input) {
StringWriter writer = null;
int len = input.length();
int i = 1;
int st = 0;
while (true) {
// Look for '&'
while (i < len && input.charAt(i-1) != '&')
i++;
if (i >= len)
break;
// Found '&', look for ';'
int j = i;
while (j < len && j < i + MAX_ESCAPE + 1 && input.charAt(j) != ';')
j++;
if (j == len || j < i + MIN_ESCAPE || j == i + MAX_ESCAPE + 1) {
i++;
continue;
}
// Found escape
if (input.charAt(i) == '#') {
// Numeric escape
int k = i + 1;
int radix = 10;
final char firstChar = input.charAt(k);
if (firstChar == 'x' || firstChar == 'X') {
k++;
radix = 16;
}
try {
int entityValue = Integer.parseInt(input.substring(k, j), radix);
if (writer == null)
writer = new StringWriter(input.length());
writer.append(input.substring(st, i - 1));
if (entityValue > 0xFFFF) {
final char[] chrs = Character.toChars(entityValue);
writer.write(chrs[0]);
writer.write(chrs[1]);
} else {
writer.write(entityValue);
}
} catch (NumberFormatException ex) {
i++;
continue;
}
}
else {
// Named escape
CharSequence value = lookupMap.get(input.substring(i, j));
if (value == null) {
i++;
continue;
}
if (writer == null)
writer = new StringWriter(input.length());
writer.append(input.substring(st, i - 1));
writer.append(value);
}
// Skip escape
st = j + 1;
i = st;
}
if (writer != null) {
writer.append(input.substring(st, len));
return writer.toString();
}
return input;
}
private static final String[][] ESCAPES = {
{"\"", "quot"}, // " - double-quote
{"&", "amp"}, // & - ampersand
{"<", "lt"}, // < - less-than
{">", "gt"}, // > - greater-than
// Mapping to escape ISO-8859-1 characters to their named HTML 3.x equivalents.
{"\u00A0", "nbsp"}, // Non-breaking space
{"\u00A1", "iexcl"}, // Inverted exclamation mark
{"\u00A2", "cent"}, // Cent sign
{"\u00A3", "pound"}, // Pound sign
{"\u00A4", "curren"}, // Currency sign
{"\u00A5", "yen"}, // Yen sign = yuan sign
{"\u00A6", "brvbar"}, // Broken bar = broken vertical bar
{"\u00A7", "sect"}, // Section sign
{"\u00A8", "uml"}, // Diaeresis = spacing diaeresis
{"\u00A9", "copy"}, // © - copyright sign
{"\u00AA", "ordf"}, // Feminine ordinal indicator
{"\u00AB", "laquo"}, // Left-pointing double angle quotation mark = left pointing guillemet
{"\u00AC", "not"}, // Not sign
{"\u00AD", "shy"}, // Soft hyphen = discretionary hyphen
{"\u00AE", "reg"}, // ® - registered trademark sign
{"\u00AF", "macr"}, // Macron = spacing macron = overline = APL overbar
{"\u00B0", "deg"}, // Degree sign
{"\u00B1", "plusmn"}, // Plus-minus sign = plus-or-minus sign
{"\u00B2", "sup2"}, // Superscript two = superscript digit two = squared
{"\u00B3", "sup3"}, // Superscript three = superscript digit three = cubed
{"\u00B4", "acute"}, // Acute accent = spacing acute
{"\u00B5", "micro"}, // Micro sign
{"\u00B6", "para"}, // Pilcrow sign = paragraph sign
{"\u00B7", "middot"}, // Middle dot = Georgian comma = Greek middle dot
{"\u00B8", "cedil"}, // Cedilla = spacing cedilla
{"\u00B9", "sup1"}, // Superscript one = superscript digit one
{"\u00BA", "ordm"}, // Masculine ordinal indicator
{"\u00BB", "raquo"}, // Right-pointing double angle quotation mark = right pointing guillemet
{"\u00BC", "frac14"}, // Vulgar fraction one quarter = fraction one quarter
{"\u00BD", "frac12"}, // Vulgar fraction one half = fraction one half
{"\u00BE", "frac34"}, // Vulgar fraction three quarters = fraction three quarters
{"\u00BF", "iquest"}, // Inverted question mark = turned question mark
{"\u00C0", "Agrave"}, // А - uppercase A, grave accent
{"\u00C1", "Aacute"}, // Б - uppercase A, acute accent
{"\u00C2", "Acirc"}, // В - uppercase A, circumflex accent
{"\u00C3", "Atilde"}, // Г - uppercase A, tilde
{"\u00C4", "Auml"}, // Д - uppercase A, umlaut
{"\u00C5", "Aring"}, // Е - uppercase A, ring
{"\u00C6", "AElig"}, // Ж - uppercase AE
{"\u00C7", "Ccedil"}, // З - uppercase C, cedilla
{"\u00C8", "Egrave"}, // И - uppercase E, grave accent
{"\u00C9", "Eacute"}, // Й - uppercase E, acute accent
{"\u00CA", "Ecirc"}, // К - uppercase E, circumflex accent
{"\u00CB", "Euml"}, // Л - uppercase E, umlaut
{"\u00CC", "Igrave"}, // М - uppercase I, grave accent
{"\u00CD", "Iacute"}, // Н - uppercase I, acute accent
{"\u00CE", "Icirc"}, // О - uppercase I, circumflex accent
{"\u00CF", "Iuml"}, // П - uppercase I, umlaut
{"\u00D0", "ETH"}, // Р - uppercase Eth, Icelandic
{"\u00D1", "Ntilde"}, // С - uppercase N, tilde
{"\u00D2", "Ograve"}, // Т - uppercase O, grave accent
{"\u00D3", "Oacute"}, // У - uppercase O, acute accent
{"\u00D4", "Ocirc"}, // Ф - uppercase O, circumflex accent
{"\u00D5", "Otilde"}, // Х - uppercase O, tilde
{"\u00D6", "Ouml"}, // Ц - uppercase O, umlaut
{"\u00D7", "times"}, // Multiplication sign
{"\u00D8", "Oslash"}, // Ш - uppercase O, slash
{"\u00D9", "Ugrave"}, // Щ - uppercase U, grave accent
{"\u00DA", "Uacute"}, // Ъ - uppercase U, acute accent
{"\u00DB", "Ucirc"}, // Ы - uppercase U, circumflex accent
{"\u00DC", "Uuml"}, // Ь - uppercase U, umlaut
{"\u00DD", "Yacute"}, // Э - uppercase Y, acute accent
{"\u00DE", "THORN"}, // Ю - uppercase THORN, Icelandic
{"\u00DF", "szlig"}, // Я - lowercase sharps, German
{"\u00E0", "agrave"}, // а - lowercase a, grave accent
{"\u00E1", "aacute"}, // б - lowercase a, acute accent
{"\u00E2", "acirc"}, // в - lowercase a, circumflex accent
{"\u00E3", "atilde"}, // г - lowercase a, tilde
{"\u00E4", "auml"}, // д - lowercase a, umlaut
{"\u00E5", "aring"}, // е - lowercase a, ring
{"\u00E6", "aelig"}, // ж - lowercase ae
{"\u00E7", "ccedil"}, // з - lowercase c, cedilla
{"\u00E8", "egrave"}, // и - lowercase e, grave accent
{"\u00E9", "eacute"}, // й - lowercase e, acute accent
{"\u00EA", "ecirc"}, // к - lowercase e, circumflex accent
{"\u00EB", "euml"}, // л - lowercase e, umlaut
{"\u00EC", "igrave"}, // м - lowercase i, grave accent
{"\u00ED", "iacute"}, // н - lowercase i, acute accent
{"\u00EE", "icirc"}, // о - lowercase i, circumflex accent
{"\u00EF", "iuml"}, // п - lowercase i, umlaut
{"\u00F0", "eth"}, // р - lowercase eth, Icelandic
{"\u00F1", "ntilde"}, // с - lowercase n, tilde
{"\u00F2", "ograve"}, // т - lowercase o, grave accent
{"\u00F3", "oacute"}, // у - lowercase o, acute accent
{"\u00F4", "ocirc"}, // ф - lowercase o, circumflex accent
{"\u00F5", "otilde"}, // х - lowercase o, tilde
{"\u00F6", "ouml"}, // ц - lowercase o, umlaut
{"\u00F7", "divide"}, // Division sign
{"\u00F8", "oslash"}, // ш - lowercase o, slash
{"\u00F9", "ugrave"}, // щ - lowercase u, grave accent
{"\u00FA", "uacute"}, // ъ - lowercase u, acute accent
{"\u00FB", "ucirc"}, // ы - lowercase u, circumflex accent
{"\u00FC", "uuml"}, // ь - lowercase u, umlaut
{"\u00FD", "yacute"}, // э - lowercase y, acute accent
{"\u00FE", "thorn"}, // ю - lowercase thorn, Icelandic
{"\u00FF", "yuml"}, // я - lowercase y, umlaut
};
private static final int MIN_ESCAPE = 2;
private static final int MAX_ESCAPE = 6;
private static final HashMap<String, CharSequence> lookupMap;
static {
lookupMap = new HashMap<String, CharSequence>();
for (final CharSequence[] seq : ESCAPES)
lookupMap.put(seq[1].toString(), seq[0]);
}
}
Utilidades HTML de Spring Framework
Si ya está utilizando Spring Framework, utilice el siguiente método:
import static org.springframework.web.util.HtmlUtils.htmlUnescape;
...
String result = htmlUnescape(source);
