日期格式的字符串，可能有以下格式：
'2008-10-11'
'2009-10-11 23:22'（日期和时间之间是空格）
'2009-10-11 23:22:49'
日期分隔符可以是'-','/','.'，但这3种情况下时间分隔符一定是':'
日期也可能是'年月日'，但此时时间分隔符可能是':'（'2009年01月11日 23:22:23'），也可能是'时分秒'（'2009年01月11日 23时22分23秒'）
不会出现其他情况
求验证表达式，并能转化为java.util.Date
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比较复杂
(\d{4}[-/\.]{1}\d{2}[-/\.]{1}\d{2}(\s{1}\d{2}:\d{2}(:\d{2}){0,1}){0,1})
|
(\d{4}年}\d{2}月\d{2}日(\s{1}\d{2}:\d{2}(:\d{2}){0,1}){0,1})
|
(\d{4}年}\d{2}月\d{2}日(\s{1}\d{2}时\d{2}分(\d{2}秒){0,1}){0,1})
分成了三个分支结构，由“|”(意同或)连接。
其中对于月份，日期，时，分，秒等数字合理性的判断没写在里面，免得太长，影响阅读理解。
具体数字的范围判断如下，可以逐个按照位置上面的正则里
月 0{1}/d{1}|10|11|12
日 [0-2]{1}/d{1}|30|31
时 [0-1]{1}/d{1}|20|21|22|23
分 [0-5]{1}/d{1}
秒 [0-5]{1}/d{1}
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关注,坐坐sf.
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前不久我也问过正则表达式的，呵呵，帮顶了，感觉正则表达式功能很大！
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个人看法，别自己跟自己过不去
从设计上将，一个日期同时出现你说的几个情况本身就是个错误。
从另一个角度讲，你完全可以
1 将/-等全部去掉
2 然后直接解析 20090110 这样的格式
3 包含时间的应该单独解析，我从未遇到过同时允许没有时间的情况
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顶java2000_net
不要把简单的事情复杂化~
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由于日期涉及闰年、大月、小月问题，因此日期的正则表达式非常复杂，加上又有那么多的格式和时间，
写出来的话，正则表达式字符长度将会超过 400 个字符。
建议使用正则表达式验证基本的数据格式，至于数据的合法性应采用代码逻辑进行验证。
原来在 CSDN 的 blog 里写的，带有行内嵌注释：
- Java code
1. import java.util.regex.Matcher; 2. import java.util.regex.Pattern; 3. 4. public class DateRegex { 5. 6. public static void main(String[] args) { 7. String[] str = { 8. "2001-00-00", "2001-01-01", "2001-01-30", "2001-01-31", 9. "2001-01-32", "2001-02-01", "2001-02-27", "2001-02-28", 10. "2004-02-29", "2001-02-29", "2001-02-30", "2001-02-31", 11. "2001-02-32", "2001-03-01", "2001-03-10", "2001-03-29", 12. "2001-03-30", "2001-03-31", "2001-03-32", "2001-04-01", 13. "2001-04-10", "2001-04-29", "2001-04-30", "2001-04-31", 14. "2001-04-32", "2001-05-01", "2001-05-10", "2001-05-29", 15. "2001-05-30", "2001-05-31", "2001-05-32", "2001-06-01", 16. "2001-06-10", "2001-06-29", "2001-06-30", "2001-06-31", 17. "2001-06-32", "2001-07-01", "2001-07-10", "2001-07-29", 18. "2001-07-30", "2001-07-31", "2001-07-32", "2001-08-01", 19. "2001-08-10", "2001-08-29", "2001-08-30", "2001-08-31", 20. "2001-08-32", "2001-09-01", "2001-09-10", "2001-09-29", 21. "2001-09-30", "2001-09-31", "2001-09-32", "2001-10-01", 22. "2001-10-10", "2001-10-29", "2001-10-30", "2001-10-31", 23. "2001-10-32", "2001-11-01", "2001-11-10", "2001-11-29", 24. "2001-11-30", "2001-11-31", "2001-11-32", "2001-12-01", 25. "2001-12-10", "2001-12-29", "2001-12-30", "2001-12-31", 26. "2001-12-32", "2001-13-01", "2001-13-10", "2001-13-29", 27. "2001-13-30", "2001-13-31", "2001-13-32", "245-12-04", 28. "100-02-29" , "200-02-29" , "300-02-29" , "400-02-29", 29. "500-02-29" , "800-02-29" , "900-02-29" , "2008-02-29", 30. "1900-02-29", "2000-02-29", "1-01-01" , "1-02-28", 31. "0-01-01" , "1-12-31" , "351-02-29" , "352-02-29", 32. "353-02-29" , "354-02-29" , "355-02-29" , "356-02-29", 33. "357-02-29" , "358-02-29" , "350-02-29" , "1-02-29", 34. "2-02-29" , "3-02-29" , "4-02-29" , "5-02-29", 35. "6-02-29" , "7-02-29" , "8-02-29" , "9-02-29", 36. "10-02-29" , "11-02-29" , "12-02-29" , "13-02-29", 37. "14-02-29" , "15-02-29" , "16-02-29" , "17-02-29", 38. "18-02-29" , "19-02-29" , "20-02-29" , "21-02-29", 39. "22-02-29" , "23-02-29" , "24-02-29" , "25-02-29", 40. "26-02-29" , "27-02-29" , "28-02-29" , "29-02-29", 41. "0-01-12" , "00-01-12" , "000-01-12" , "0000-01-12", 42. "0028-02-29" 43. }; 44. 45. String moreMonth = 46. "(?: \n" + 47. " ## 日期前是大月 \n" + 48. " ## 01 03 05 07 08 \n" + 49. " ## 10 12 月 \n" + 50. " (?<= \n" + 51. " (?: \n" + 52. " 0[13578] \n" + 53. " | \n" + 54. " 1[02] \n" + 55. " ) \n" + 56. " - \n" + // 分隔符 57. " ) \n" + 58. " (?: \n" + 59. " ## 大月的日期 29 \n" + 60. " 29 \n" + 61. " | \n" + 62. " ## 大月的日期 30~31 \n" + 63. " 3[01] \n" + 64. " ) \n" + 65. ") \n"; 66. 67. String lesserMonth = 68. "(?: \n" + 69. " ## 日期前是小月 \n" + 70. " ## 04 06 09 11 月 \n" + 71. " (?<= \n" + 72. " (?: \n" + 73. " 0[469] \n" + 74. " | \n" + 75. " 11 \n" + 76. " ) \n" + 77. " - \n" + // 分隔符 78. " ) \n" + 79. " (?: \n" + 80. " ## 小月的日期 29 \n" + 81. " 29 \n" + 82. " | \n" + 83. " ## 小月的日期 30~31 \n" + 84. " 30 \n" + 85. " ) \n" + 86. ") \n"; 87.