Java正则表达式

1. 两个问题

           a. 如何知道一个url是新浪论坛的帖子页

           b. 如何提取这些页面的发帖时间

 

    分析：

           新浪论坛的帖子页url实例：

            http://bbs.2008.sina.com.cn/tableforum/App/view.php?bbsid=274&subid=0&fid=32614&tbid=2351

           http://bbs.book.sina.com.cn/tableforum/App/view.php?bbsid=7&subid=1&fid=43640&tbid=5386

           http://bbs.book.sina.com.cn/tableforum/App/view.php?bbsid=192&subid=4&fid=10367&tbid=1683

           http://bbs.edu.sina.com.cn/tableforum/App/view.php?bbsid=41&subid=2&fid=86455&tbid=4803

 

  发现很有规律。规则差不多是这样：

http://bbs\.[a-zA-Z0-9]+\.sina\.com\.cn/tableforum/App/view.php\?bbsid=[0-9]+&subid=[0-9]+&fid=[0-9]+&tbid=[0-9 ]+     (.与?需要转义,写成\.与\?)

 

发帖时间都这样的：[2008-08-09 14:51:35] 

   规则：\[ (\d\d\d\d-\d\d-\d\d \d\d:\d\d:\d\d)\]

 

 

 Regular Expression Syntax

Syntax

Explanation

Characters
c	The character c
\ unnnn , \ xnn, \ 0n , \ 0nn , \ 0nnn	The code unit with the given hex or octal value
\ t, \ n, \ r, \ f, \ a, \e	The control characters tab, newline, return, form feed, alert, and escape
\ cc	The control character corresponding to the character c
Character Classes
[ C 1 C 2 . . .]	Any of the characters represented by C 1 , C 2 , . . . The Ci are characters, character ranges (c 1 -c 2 ), or character classes
[^ . . .]	Complement of character class
[ . . . && . . .]	Intersection of two character classes
Predefined Character Classes
.	Any character except line terminators (or any character if the DOTALL flag is set)
\d	A digit [0-9 ]
\D	A nondigit [^0-9 ]
\s	A whitespace character [ \t\n\r\f\x0B ]
\S	A non-whitespace character
\w	A word character [a-zA-Z0-9 _]
\W	A nonword character
\p{ name }	A named character class—see Table 12-9
\P{ name }	The complement of a named character class
Boundary Matchers
^ $	Beginning, end of input (or beginning, end of line in multiline mode)
\b	A word boundary
\B	A nonword boundary
Syntax	Explanation
\A	Beginning of input
\z	End of input
\Z	End of input except final line terminator
\G	End of previous match
Quantifiers
X?	Optional X
X*	X, 0 or more times
X +	X, 1 or more times
X {n } X {n ,} X {n,m }	X n times, at least n times, between n and m times
Quantifier Suffixes
?	Turn default (greedy) match into reluctant match
+	Turn default (greedy) match into possessive match
Set Operations
XY	Any string from X , followed by any string from Y
X|Y	Any string from X or Y
Grouping
(X)	Capture the string matching X as a group
\ n	The match of the n th group
Escapes
\ c	The character c (must not be an alphabetic character)
\ Q . . . \E	Quote . . . verbatim
(? . . . )	Special construct—see API notes of Pattern class

 

 

从html中去除标签，提取正文的正则表达式：

<script.*?</script>|<style.*?</style>|<!?[a-z]+[^>]*>|</[a-z0-9]+>|<!--.*?-->

 

上传一个正则表达式测试工具：