问题描述
基本上，我想解码一个给定的 Html 文档，并替换所有特殊的字符，如" " – > " "，">" – > ">"。
在.NET 中，我们可以使用 HttpUtility.HtmlDecode 。
Java 中的等效功能是什么？
最佳解决方案
我已经使用 Apache Commons StringEscapeUtils.unescapeHtml4()为此：
Unescapes a string containing entity escapes to a string containing the actual Unicode characters corresponding to the escapes. Supports HTML 4.0 entities.
次佳解决方案
我在我的项目中尝试过 Apache Commons StringEscapeUtils.unescapeHtml3()，但对其性能不满意。原来，它做了很多不必要的操作。对于一个，它为每个调用分配一个 StringWriter，即使在字符串中没有任何东西可以解压缩。我已经重写了这个代码，现在它的工作速度要快得多。谁可以发现这个在谷歌是欢迎使用它。
以下代码取消所有 HTML 3 符号和数字转义 (相当于 Apache unescapeHtml3) 。如果您需要 HTML 4，您可以向 Map 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]);
}
}
第三种解决方案
其他答案中提到的图书将是很好的解决方案，但是如果您已经碰巧在您的项目中通过 real-world html 挖掘，那么 Jsoup 项目比管理 「和号磅 FFFF 分号」 的东西还要更多。
// textValue: <p>This is a sample. "Granny" Smith –.</p>rn
// 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 unescapeEntities(String string, boolean inAttribute);
而且，您还可以使用最佳的 DOM，CSS 和 jquery-like 方法获取方便的 API 来提取和操作数据。它是开源和麻省理工学院的许可证。
第四种方案
以下库也可用于 Java 中的 HTML 转义：unbescape 。
HTML 可以通过以下方式进行转义：
final String unescapedText = HtmlEscape.unescapeHtml(escapedText);
参考文献
注：本文内容整合自 Google/Baidu/Bing 辅助翻译的英文资料结果。如果您对结果不满意，可以加入我们改善翻译效果：薇晓朵技术论坛。