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别有一番风味的正则表达式

2024-11-25 来源：个人技术集锦

针对这样需要，我们可以采用类似于如下的方式实现。

    public boolean isAlphaNumeric(String value) {
        if(StringUtils.isEmpty(value)){
            return false;
        }
        return value.matches("^[a-zA-Z0-9]*$");
    }

在类中，其实除了字符类或者预定义字符类，如：

Character classes
[abc]	a, b, or c (simple class)
[^abc]	Any character except a, b, or c (negation)
[a-zA-Z]	a through z or A through Z, inclusive (range)
[a-d[m-p]]	a through d, or m through p: [a-dm-p] (union)
[a-z&&[def]]	d, e, or f (intersection)
[a-z&&[^bc]]	a through z, except for b and c: [ad-z] (subtraction)
[a-z&&[^m-p]]	a through z, and not m through p: [a-lq-z](subtraction)
 

Predefined character classes
.	Any character (may or may not match line terminators)
\d	A digit: [0-9]
\D	A non-digit: [^0-9]
\s	A whitespace character: [ \t\n\x0B\f\r]
\S	A non-whitespace character: [^\s]
\w	A word character: [a-zA-Z_0-9]
\W	A non-word character: [^\w]

参考

之外，还支持Unicode 字符属性别名 , POSIX 正则表达式字符类以及java字符类型等。让我们一起来看一下相关的源代码和API的说明，然后尝试一下能写出什么不一样的正则表达式出来。走起~~~

Unicode字符属性别名

// Unicode character property aliases, defined in
            // http://www.unicode.org/Public/UNIDATA/PropertyValueAliases.txt
            defCategory("Cn", 1<<Character.UNASSIGNED);
            defCategory("Lu", 1<<Character.UPPERCASE_LETTER);
            defCategory("Ll", 1<<Character.LOWERCASE_LETTER);
            defCategory("Lt", 1<<Character.TITLECASE_LETTER);
            defCategory("Lm", 1<<Character.MODIFIER_LETTER);
            defCategory("Lo", 1<<Character.OTHER_LETTER);
            defCategory("Mn", 1<<Character.NON_SPACING_MARK);
            defCategory("Me", 1<<Character.ENCLOSING_MARK);
            defCategory("Mc", 1<<Character.COMBINING_SPACING_MARK);
            defCategory("Nd", 1<<Character.DECIMAL_DIGIT_NUMBER);
            defCategory("Nl", 1<<Character.LETTER_NUMBER);
            defCategory("No", 1<<Character.OTHER_NUMBER);
            defCategory("Zs", 1<<Character.SPACE_SEPARATOR);
            defCategory("Zl", 1<<Character.LINE_SEPARATOR);
            defCategory("Zp", 1<<Character.PARAGRAPH_SEPARATOR);
            defCategory("Cc", 1<<Character.CONTROL);
            defCategory("Cf", 1<<Character.FORMAT);
            defCategory("Co", 1<<Character.PRIVATE_USE);
            defCategory("Cs", 1<<Character.SURROGATE);
            defCategory("Pd", 1<<Character.DASH_PUNCTUATION);
            defCategory("Ps", 1<<Character.START_PUNCTUATION);
            defCategory("Pe", 1<<Character.END_PUNCTUATION);
            defCategory("Pc", 1<<Character.CONNECTOR_PUNCTUATION);
            defCategory("Po", 1<<Character.OTHER_PUNCTUATION);
            defCategory("Sm", 1<<Character.MATH_SYMBOL);
            defCategory("Sc", 1<<Character.CURRENCY_SYMBOL);
            defCategory("Sk", 1<<Character.MODIFIER_SYMBOL);
            defCategory("So", 1<<Character.OTHER_SYMBOL);
            defCategory("Pi", 1<<Character.INITIAL_QUOTE_PUNCTUATION);
            defCategory("Pf", 1<<Character.FINAL_QUOTE_PUNCTUATION);
            defCategory("L", ((1<<Character.UPPERCASE_LETTER) |
                              (1<<Character.LOWERCASE_LETTER) |
                              (1<<Character.TITLECASE_LETTER) |
                              (1<<Character.MODIFIER_LETTER)  |
                              (1<<Character.OTHER_LETTER)));
            defCategory("M", ((1<<Character.NON_SPACING_MARK) |
                              (1<<Character.ENCLOSING_MARK)   |
                              (1<<Character.COMBINING_SPACING_MARK)));
            defCategory("N", ((1<<Character.DECIMAL_DIGIT_NUMBER) |
                              (1<<Character.LETTER_NUMBER)        |
                              (1<<Character.OTHER_NUMBER)));
            defCategory("Z", ((1<<Character.SPACE_SEPARATOR) |
                              (1<<Character.LINE_SEPARATOR)  |
                              (1<<Character.PARAGRAPH_SEPARATOR)));
            defCategory("C", ((1<<Character.CONTROL)     |
                              (1<<Character.FORMAT)      |
                              (1<<Character.PRIVATE_USE) |
                              (1<<Character.SURROGATE))); // Other
            defCategory("P", ((1<<Character.DASH_PUNCTUATION)      |
                              (1<<Character.START_PUNCTUATION)     |
                              (1<<Character.END_PUNCTUATION)       |
                              (1<<Character.CONNECTOR_PUNCTUATION) |
                              (1<<Character.OTHER_PUNCTUATION)     |
                              (1<<Character.INITIAL_QUOTE_PUNCTUATION) |
                              (1<<Character.FINAL_QUOTE_PUNCTUATION)));
            defCategory("S", ((1<<Character.MATH_SYMBOL)     |
                              (1<<Character.CURRENCY_SYMBOL) |
                              (1<<Character.MODIFIER_SYMBOL) |
                              (1<<Character.OTHER_SYMBOL)));
            defCategory("LC", ((1<<Character.UPPERCASE_LETTER) |
                               (1<<Character.LOWERCASE_LETTER) |
                               (1<<Character.TITLECASE_LETTER)));
            defCategory("LD", ((1<<Character.UPPERCASE_LETTER) |
                               (1<<Character.LOWERCASE_LETTER) |
                               (1<<Character.TITLECASE_LETTER) |
                               (1<<Character.MODIFIER_LETTER)  |
                               (1<<Character.OTHER_LETTER)     |
                               (1<<Character.DECIMAL_DIGIT_NUMBER)));
            defRange("L1", 0x00, 0xFF); // Latin-1
            map.put("all", new CharPropertyFactory() {
                    CharProperty make() { return new All(); }});

 

\p{Lu}	            An uppercase letter (category)
[\p{L}&&[^\p{Lu}]] 	Any letter except an uppercase letter (subtraction)

示例

判断是否由大写字母组成
        /**
		 * 判断是否都是由大写字母组成
		 */
		String regexExp = "^[\\p{Lu}]*$";
		System.out.println("a".matches(regexExp));// false
		System.out.println("B".matches(regexExp));// true
		System.out.println("aB".matches(regexExp));// false
		System.out.println("@".matches(regexExp));// false

POSIX 字符类（仅 US-ASCII） 

  // Posix regular expression character classes, defined in
            // http://www.unix.org/onlinepubs/009695399/basedefs/xbd_chap09.html
            defRange("ASCII", 0x00, 0x7F);   // ASCII
            defCtype("Alnum", ASCII.ALNUM);  // Alphanumeric characters
            defCtype("Alpha", ASCII.ALPHA);  // Alphabetic characters
            defCtype("Blank", ASCII.BLANK);  // Space and tab characters
            defCtype("Cntrl", ASCII.CNTRL);  // Control characters
            defRange("Digit", '0', '9');     // Numeric characters
            defCtype("Graph", ASCII.GRAPH);  // printable and visible
            defRange("Lower", 'a', 'z');     // Lower-case alphabetic
            defRange("Print", 0x20, 0x7E);   // Printable characters
            defCtype("Punct", ASCII.PUNCT);  // Punctuation characters
            defCtype("Space", ASCII.SPACE);  // Space characters
            defRange("Upper", 'A', 'Z');     // Upper-case alphabetic
            defCtype("XDigit",ASCII.XDIGIT); // hexadecimal digits

 

POSIX character classes (US-ASCII only)

\p{Lower}	A lower-case alphabetic character: [a-z]
\p{Upper}	An upper-case alphabetic character:[A-Z]
\p{ASCII}	All ASCII:[\x00-\x7F]
\p{Alpha}	An alphabetic character:[\p{Lower}\p{Upper}]
\p{Digit}	A decimal digit: [0-9]
\p{Alnum}	An alphanumeric character:[\p{Alpha}\p{Digit}]
\p{Punct}	Punctuation: One of !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~
\p{Graph}	A visible character: [\p{Alnum}\p{Punct}]
\p{Print}	A printable character: [\p{Graph}\x20]
\p{Blank}	A space or a tab: [ \t]
\p{Cntrl}	A control character: [\x00-\x1F\x7F]
\p{XDigit}	A hexadecimal digit: [0-9a-fA-F]

示例

判断是否由ASCII值组成
        /**
		 * 判断是否由ASCII码组成
		 */
		String regexExp = "^[\\p{ASCII}]*$";
		System.out.println("a".matches(regexExp));// true
		System.out.println("1".matches(regexExp));// true
		System.out.println("-".matches(regexExp));// true
		System.out.println("@".matches(regexExp));// true
		System.out.println("我".matches(regexExp));// false
判断是否由小写字母组成
		/**
		 * 判断是否由小写字母组成
		 */
		String regexExp = "^[\\p{Lower}]*$";
		System.out.println("a".matches(regexExp));// true
		System.out.println("1".matches(regexExp));// false
		System.out.println("-".matches(regexExp));// false
		System.out.println("@".matches(regexExp));// false
		System.out.println("B".matches(regexExp));// false
判断是是否是有数字组成
		/**
		 * 判断是否由数字组成
		 */
		String regexExp = "^[\\p{Digit}]*$";
		System.out.println("a".matches(regexExp));// false
		System.out.println("1".matches(regexExp));// true
		System.out.println("-".matches(regexExp));// false
		System.out.println("@".matches(regexExp));// false
		System.out.println("B".matches(regexExp));// false

剩余的，如Upper用于判断是否由大写字母组成等，有兴趣的读者可以自己写一下。

java.lang.Character 类（简单的 java 字符类型） 

 // Java character properties, defined by methods in Character.java
            defClone("javaLowerCase", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isLowerCase(ch);}});
            defClone("javaUpperCase", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isUpperCase(ch);}});
            defClone("javaAlphabetic", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isAlphabetic(ch);}});
            defClone("javaIdeographic", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isIdeographic(ch);}});
            defClone("javaTitleCase", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isTitleCase(ch);}});
            defClone("javaDigit", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isDigit(ch);}});
            defClone("javaDefined", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isDefined(ch);}});
            defClone("javaLetter", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isLetter(ch);}});
            defClone("javaLetterOrDigit", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isLetterOrDigit(ch);}});
            defClone("javaJavaIdentifierStart", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isJavaIdentifierStart(ch);}});
            defClone("javaJavaIdentifierPart", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isJavaIdentifierPart(ch);}});
            defClone("javaUnicodeIdentifierStart", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isUnicodeIdentifierStart(ch);}});
            defClone("javaUnicodeIdentifierPart", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isUnicodeIdentifierPart(ch);}});
            defClone("javaIdentifierIgnorable", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isIdentifierIgnorable(ch);}});
            defClone("javaSpaceChar", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isSpaceChar(ch);}});
            defClone("javaWhitespace", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isWhitespace(ch);}});
            defClone("javaISOControl", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isISOControl(ch);}});
            defClone("javaMirrored", new CloneableProperty() {
                boolean isSatisfiedBy(int ch) {
                    return Character.isMirrored(ch);}});

参考 

java.lang.Character classes (simple java character type)

\p{javaLowerCase}	Equivalent to java.lang.Character.isLowerCase()
\p{javaUpperCase}	Equivalent to java.lang.Character.isUpperCase()
\p{javaWhitespace}	Equivalent to java.lang.Character.isWhitespace()
\p{javaMirrored}	Equivalent to java.lang.Character.isMirrored()

示例

判断是否由小写字母组成
		/**
		 * 判断是否由小写字母组成
		 */
		String regexExp = "^[\\p{javaLowerCase}]*$";
		System.out.println("a".matches(regexExp));// true
		System.out.println("1".matches(regexExp));// false
		System.out.println("-".matches(regexExp));// false
		System.out.println("@".matches(regexExp));// false
		System.out.println("B".matches(regexExp));// false
判断是否由数字或者字母组成
		/**
		 * 判断是否由数字或者字母组成
		 */
		String regexExp = "^[\\p{javaLetterOrDigit}]*$";
		System.out.println("a".matches(regexExp));// true
		System.out.println("1".matches(regexExp));// true
		System.out.println("-".matches(regexExp));// false
		System.out.println("@".matches(regexExp));// false
		System.out.println("B1".matches(regexExp));// true

小结

通过上述示例的编写，想必大家对判断数字、字母、ASCII码等正则表达式的编写，又多了几种写法了。

转载于:https://my.oschina.net/wangmengjun/blog/780908
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