问题
基本上我想解码给定的Html文档，并替换所有特殊字符，例如" "-> " ",">"-> ">"。
在.NET中我们可以使用HttpUtility.HtmlDecode。
什么是Java中的等效函数？
#1 热门回答(150 赞)
我使用了Apache CommonsStringEscapeUtils.unescapeHtml4()：
Unescapes包含实体转义的字符串转义为包含与转义对应的实际Unicode字符的字符串。支持HTML 4.0实体。
#2 热门回答(35 赞)
我在我的项目中尝试过Apache Commons StringEscapeUtils.unescapeHtml3()，但对其性能不满意。事实证明，它做了很多不必要的操作。首先，它为每个调用分配一个StringWriter，即使字符串中没有任何东西可以取景。我以不同的方式重写了代码，现在它的工作速度要快得多。无论谁在谷歌找到这个，欢迎使用它。
下面的代码unescapes所有HTML 3符号和数字转义(相当于Apache unescapeHtml3)。如果需要HTML 4，可以在 Map 中添加更多条目。
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]);
}
}
#3 热门回答(23 赞)
其他答案中提到的库将是很好的解决方案，但如果你已经在项目中挖掘了真实世界的html，那么Jsoup项目除了管理"＆符号FFFF分号"之外还有很多其他功能。
// 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);
而且，你还可以使用最好的DOM，CSS和类似jquery的方法来获取用于提取和操作数据的便捷API。它是开源和MIT许可证。