別有一番風味的正則表達式
寫一個用於判斷給定字符串是否只包含數字或者字母的正則表達式。html
針對這樣須要，咱們能夠採用相似於以下的方式實現。java
public boolean isAlphaNumeric(String value) {
if(StringUtils.isEmpty(value)){
return false;
}
return value.matches("^[a-zA-Z0-9]*$");
}
在java.util.regex.Pattern類中，其實除了字符類或者預約義字符類，如：git
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]
參考https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html正則表達式
以外，還支持Unicode 字符屬性別名 , POSIX 正則表達式字符類以及java字符類型等。讓咱們一塊兒來看一下相關的源代碼和API的說明，而後嘗試一下能寫出什麼不同的正則表達式出來。走起~~~express
Unicode字符屬性別名
// 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
判斷是否由大寫字母組成
/**
* 判斷是否都是由大寫字母組成
*/
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 字符類（僅 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
判斷是否由ASCII值組成
/**
* 判斷是否由ASCII碼組成
*/
String regexExp = "^[\\p{ASCII}]*$";
System.out.println("a".matches(regexExp));// true
System.out.println("1".matches(regexExp));// true
System.out.println("-".matches(regexExp));// true
System.out.println("@".matches(regexExp));// true
System.out.println("我".matches(regexExp));// false
判斷是否由小寫字母組成
/**
* 判斷是否由小寫字母組成
*/
String regexExp = "^[\\p{Lower}]*$";
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
判斷是是不是有數字組成
/**
* 判斷是否由數字組成
*/
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
剩餘的，如Upper用於判斷是否由大寫字母組成等，有興趣的讀者能夠本身寫一下。api
java.lang.Character 類（簡單的 java 字符類型）
// 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);}});
參考 https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.htmloracle
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
判斷是否由小寫字母組成
/**
* 判斷是否由小寫字母組成
*/
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
判斷是否由數字或者字母組成
/**
* 判斷是否由數字或者字母組成
*/
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
小結
經過上述示例的編寫，想必你們對判斷數字、字母、ASCII碼等正則表達式的編寫，又多了幾種寫法了。ui
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