十个你需要知道的正则表达式_角色正则怎么填?-优快云博客

本文介绍了10种常用的正则表达式实例，包括用户名、密码、十六进制颜色、邮件地址、图片文件名、IP地址、时间、日期、HTML标签及HTML链接等。每个实例都详细解释了正则表达式的组成部分，帮助读者更好地理解和使用。

正则表达式在日常开发中扮演着重要的角色，尽管它比较难debug.下面给介绍下比较常用的正则表达式的用法

1，用户名

^[a-z0-9_-]{3,15}$

^                    # Start of the line
  [a-z0-9_-]	     # Match characters and symbols in the list, a-z, 0-9 , underscore , hyphen
             {3,15}  # Length at least 3 characters and maximum length of 15 
$                    # End of the line

2，密码

((?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%]).{6,20})

(			# Start of group
  (?=.*\d)		#   must contains one digit from 0-9
  (?=.*[a-z])		#   must contains one lowercase characters
  (?=.*[A-Z])		#   must contains one uppercase characters
  (?=.*[@#$%])		#   must contains one special symbols in the list "@#$%"
              .		#     match anything with previous condition checking
                {6,20}	#        length at least 6 characters and maximum of 20	
)			# End of group

3，十六进制颜色

^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$

^		 #start of the line
 #		 #  must constains a "#" symbols
 (		 #  start of group #1
  [A-Fa-f0-9]{6} #    any strings in the list, with length of 6
  |		 #    ..or
  [A-Fa-f0-9]{3} #    any strings in the list, with length of 3
 )		 #  end of group #1 
$		 #end of the line

4，邮件

^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$

^			#start of the line
  [_A-Za-z0-9-]+	#  must start with string in the bracket [ ], must contains one or more (+)
  (			#  start of group #1
    \\.[_A-Za-z0-9-]+	#     follow by a dot "." and string in the bracket [ ], must contains one or more (+)
  )*			#  end of group #1, this group is optional (*)
    @			#     must contains a "@" symbol
     [A-Za-z0-9]+       #        follow by string in the bracket [ ], must contains one or more (+)
      (			#	   start of group #2 - first level TLD checking
       \\.[A-Za-z0-9]+  #	     follow by a dot "." and string in the bracket [ ], must contains one or more (+)
      )*		#	   end of group #2, this group is optional (*)
      (			#	   start of group #3 - second level TLD checking
       \\.[A-Za-z]{2,}  #	     follow by a dot "." and string in the bracket [ ], with minimum length of 2
      )			#	   end of group #3
$			#end of the line

5，图片

([^\s]+(\.(?i)(jpg|png|gif|bmp))$)

(			#Start of the group #1
 [^\s]+			#  must contains one or more anything (except white space)
       (		#    start of the group #2
         \.		#	follow by a dot "."
         (?i)		#	ignore the case sensitive checking
             (		#	  start of the group #3
              jpg	#	    contains characters "jpg"
              |		#	    ..or
              png	#	    contains characters "png"
              |		#	    ..or
              gif	#	    contains characters "gif"
              |		#	    ..or
              bmp	#	    contains characters "bmp"
             )		#	  end of the group #3
       )		#     end of the group #2	
  $			#  end of the string
)			#end of the group #1

6， IP

^([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])$

^		#start of the line
 (		#  start of group #1
   [01]?\\d\\d? #    Can be one or two digits. If three digits appear, it must start either 0 or 1
		#    e.g ([0-9], [0-9][0-9],[0-1][0-9][0-9])
    |		#    ...or
   2[0-4]\\d	#    start with 2, follow by 0-4 and end with any digit (2[0-4][0-9]) 
    |           #    ...or
   25[0-5]      #    start with 2, follow by 5 and end with 0-5 (25[0-5]) 
 )		#  end of group #2
  \.            #  follow by a dot "."
....            # repeat with 3 time (3x)
$		#end of the line

7，时间

12小时制

(1[012]|[1-9]):[0-5][0-9](\\s)?(?i)(am|pm)

(				#start of group #1
 1[012]				#  start with 10, 11, 12
 |				#  or
 [1-9]				#  start with 1,2,...9
)				#end of group #1
 :				#    follow by a semi colon (:)
  [0-5][0-9]			#   follow by 0..5 and 0..9, which means 00 to 59
            (\\s)?		#        follow by a white space (optional)
                  (?i)		#          next checking is case insensitive
                      (am|pm)	#            follow by am or pm

24小时制

([01]?[0-9]|2[0-3]):[0-5][0-9]

(				#start of group #1
 [01]?[0-9]			#  start with 0-9,1-9,00-09,10-19
 |				#  or
 2[0-3]				#  start with 20-23
)				#end of group #1
 :				#  follow by a semi colon (:)
  [0-5][0-9]			#    follow by 0..5 and 0..9, which means 00 to 59

8，日期

(0?[1-9]|[12][0-9]|3[01])/(0?[1-9]|1[012])/((19|20)\\d\\d)

(			#start of group #1
 0?[1-9]		#  01-09 or 1-9
 |                  	#  ..or
 [12][0-9]		#  10-19 or 20-29
 |			#  ..or
 3[01]			#  30, 31
) 			#end of group #1
  /			#  follow by a "/"
   (			#    start of group #2
    0?[1-9]		#	01-09 or 1-9
    |			#	..or
    1[012]		#	10,11,12
    )			#    end of group #2
     /			#	follow by a "/"
      (			#	  start of group #3
       (19|20)\\d\\d	#	    19[0-9][0-9] or 20[0-9][0-9]
       )		#	  end of group #3

9，HTML标签

<("[^"]*"|'[^']*'|[^'">])*>

<	  	#start with opening tag "<"
 (		#   start of group #1
   "[^"]*"	#	only two double quotes are allow - "string"
   |		#	..or
   '[^']*'	#	only two single quotes are allow - 'string'
   |		#	..or
   [^'">]	#	can't contains one single quotes, double quotes and ">"
 )		#   end of group #1
 *		# 0 or more
>		#end with closing tag ">"

10，html链接

(?i)]+)>(.+?)

(		#start of group #1
 ?i		#  all checking are case insensive
)		#end of group #1
]+	#     anything except (">"), at least one character
   )		#  end of group #2
  >		#     follow by ">"
    (.+?)	#	match anything 
         	#	  end with "

转自: http://thejtechs.com/blogDetail/72/%E5%8D%81%E4%B8%AA%E4%BD%A0%E9%9C%80%E8%A6%81%E7%9F%A5%E9%81%93%E7%9A%84%E6%AD%A3%E5%88%99%E8%A1%A8%E8%BE%BE%E5%BC%8F