Regular expressions commonly used in java
This article introduces the knowledge of "regular expressions commonly used in java". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!
"^ / positive $" / / non-negative integer (positive integer + 0)
"^ [0-9] * [1-9] [0-9] * $" / / positive integer
"^ (- / d+) | (0 +) $" / / non-positive integer (negative integer + 0)
"^-[0-9] * [1-9] [0-9] * $" / / negative integer
"^ -? / dumped $" / / Integer
"^ / d + (/. / d +)? $" / / non-negative floating point number (positive floating point number + 0)
"^ (([0-9] + /. [0-9] * [1-9] [0-9] *) | ([0-9] * [1-9] [0-9] * /. [0-9] +) | ([0-9] * [1-9] [0-9] *)) $" / / positive floating point number
"^ ((- / d+ (/. / d+)?) | (0 + (/ .0 +)?) $" / / non-positive floating point number (negative floating point number + 0)
"^ (- ([0-9] + /. [0-9] * [1-9] [0-9] *) | ([0-9] * [1-9] [0-9] * /. [0-9] +) | ([0-9] * [1-9] [0-9] *)) $" / / negative floating point number
"^ (-? / d +) (/. / d +)? $" / / floating point number
"^ [A-Za-z] + $" / / A string of 26 letters
"^ [Amurz] + $" / / A string of 26 English letters in uppercase
A string of 26 lowercase letters consisting of "^ [amurz] + $" / /
"^ [A-Za-z0-9] + $" / / A string of numbers and 26 letters
A string of numbers, 26 letters, or underscores
"^ [/ w -] + (/ .[ / w -] +) * @ [/ w -] + (/. [/ w -] +) + $" / / email address
"^ [a-zA-z] +: / / (/ w + (- / w +) *) (/. (/ w + (- / w +) *)) * (/? / S*)? $" / / url
/ ^ (d {2} | d {4})-(0 ([1-9] {1})) | (1 [1 | 2]))-([0-2] ([1-9] {1})) | (3 [0 | 1])) $/ year-month-day
/ ^ ((0 ([1-9] {1})) | (1 [1 | 2])) / ([0-2] ([1-9] {1})) | (3 [0 | 1])) / (d {2} | d {4}) $/ month / day / year
"^ ([wmere.] +) @ ([[0-9] {1Mague 3}. [0-9] {1pr 3}. [0-9] {1pr 3}.) | (([w -] +.)) ([a-zA-Z] {2jue 4} | [0-9] {1Mague 3}) (]?) $" / / Emil
"(dwells -)? (d {4} -? d {7} | d {3} -? d {8} | ^ d {7je 8}) (- d +)? / / phone number
"^ (d {1 1dd 2} | 1dd | 2 [0-4] d | 25 [0-5]). (d {1 IP 2} | 1dd | 2 [0-4] d | 25 [0-5]). (d {1 recorder 2} | 1dd | 2 [0-4] d | 25 [0-5]). (d {1pm 2} | 1dd | 2 [0-4] d | 25 [0-5])
Regular expression that matches Chinese characters: [/ u4e00-/u9fa5]
Match double-byte characters (including Chinese characters): [^ / x00-/xff]
Regular expression that matches blank lines: / n [/ s |] * / r
Regular expression that matches the HTML tag: /. * | /
Regular expression that matches leading and trailing spaces: (^ / s*) | (/ sworn $)
Regular expression that matches the Email address: / w + ([- +.] / w +) * @ / w + ([-.] / w +) * /. / w + ([-.] / w +) *
Regular expression that matches the URL URL: ^ [a-zA-z] +: / / (/ / w+ (- / / w+) *) (/ /. (/ / w+ (- / / w+) *) * (/ /? / / S*)? $
Whether the matching account is legal (5-16 bytes are allowed at the beginning of the letter, and alphanumeric underscores are allowed): ^ [a-zA-Z] [a-zA-Z0-9 _] {4j 15} $
Match domestic phone number: (/ d {3}-| / d {4} -)? (/ d {8} | / d {7})?
Match Tencent QQ number: ^ [1-9] * [1-9] [0-9] * $
Metacharacters and their behavior in the context of regular expressions:
Marks the next character as a special character, or a literal character, or a backward reference, or an octal escape character.
^ matches the starting position of the input string. If the Multiline property of the RegExp object is set, ^ also matches the position after'/ n'or'/ r'.
$matches the end of the input string. If the Multiline property of the RegExp object is set, $also matches the position before'/ n'or'/ r'.
* matches the previous subexpression zero or more times.
+ matches the previous subexpression one or more times. + is equivalent to {1,}.
? Matches the previous subexpression zero or once. ? It is equivalent to {0jue 1}.
{n} n is a non-negative integer that matches a determined n times.
{n,} n is a non-negative integer that matches at least n times.
{n ·m} m} m and n are non-negative integers, where n
