别有一番风味的正则表达式
发布时间：2020-12-14 00:53:10 所属栏目：百科 来源：网络整理
导读：写一个用于判断给定字符串是否只包含数字或者字母的正则表达式。 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]*
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java.util.regex.Pattern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,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: [ tnx0Bfr] S A non-whitespace character: [^s] w A word character: [a-zA-Z_0-9] W A non-word character: [^w] 参考https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html 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",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 !"#$%&'()*+,-./:;<=>?@[]^_`{|}~
p{Graph} A visible character: [p{Alnum}p{Punct}]
p{Print} A printable character: [p{Graph}x20]
p{Blank} A space or a tab: [ t]
p{Cntrl} A control character: [x00-x1Fx7F]
p{XDigit} A hexadecimal digit: [0-9a-fA-F]
示例判断是否由ASCII值组成/**
* 判断是否由ASCII码组成
*/
String regexExp = "^[p{ASCII}]*$";
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
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https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html 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
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