Question

我正在Java程序中使用以下正则表达式。

sayHi()function

我从任何站点获得的此正则表达式。只是想知道此正则表达式中将要遵循的内容

Person.prototype.sayHi

以上部分将做什么。上面提到的字符是什么符号？

此外，通过使用上述正则表达式，我能够在Java程序中匹配单个斜杠“ \”，但不能匹配双反斜杠“ \”。怎么做？

此正则表达式有问题吗？我想使用Java在我的代码中排除所有这些字符。此正则表达式可以在javascript代码上正常工作，但不能在Java代码上正常工作。

Answer 1

我相信正则表达式并不是您在问题中所写的。您写的是Java字符串文字：

String regex = "^[-!$%^&*()+|~=`\\\\#{}\\[\\]:;<>?,.\\/@\\b\\r\\t\\Z\\%\\n\\0\\_\\'\\\"\\\\]$";

如果确实如此，则它是无效的正则表达式，使用时会引起PatternSyntaxException。
如果不是这种情况，则正则表达式完全没有意义，但请参阅此答案的后面。
首先，我假设它是字符串文字。

Java字符串文字使用\来转义特殊字符，如Java Language Specification中所述，因此上面的代码是此正则表达式：

^[-!$%^&*()+|~=`\\#{}\[\]:;<>?,.\/@\b\r\t\Z\%\n\0\_\'\"\\]$

正则表达式也使用\来转义特殊字符，如Pattern的javadoc中所述，它表示：

^                  Match beginning of input
[                  Start of character class, i.e. match any of the following characters:
  -                  Minus sign. Is special in a character class,
                         but can be unescaped if first or last
  !$%^&*()+|~=`      Any of those characters
  \\                 \ is the escape character, so it is escaped
  #{}                Any of those characters
  \[\]               [] brackets have special meaning, so they are escaped
  :;<>?,.            Any of those characters
  \/                 Unnecessary escape of /, probably because regex was designed
                         for non-Java use
  @                  That character
  \b                 Undefined, causes PatternSyntaxException
  \r                 Carriage-return character ('\u000D')
  \t                 Tab character ('\u0009')
  \Z                 Undefined, causes PatternSyntaxException
  \%                 Unnecessary escape of %
  \n                 Newline (line feed) character ('\u000A')
  \0                 Undefined, causes PatternSyntaxException
  \_                 Unnecessary escape of _
  \'                 Unnecessary escape of '
  \"                 Unnecessary escape of "
  \\                 Redundant, since \ is already added earlier
]                  End of character class
$                  Match end of input

如果正则表达式确实是您编写的：

^                  Match beginning of input
[                  Start of character class, i.e. match any of the following characters:
  -                  Minus sign. Is special in a character class,
                         but can be unescaped if first or last
  !$%^&*()+|~=`      Any of those characters
  \\                 \ is the escape character, so it is escaped
  \\                 Redundant, since \ is already added earlier
  #{}                Any of those characters
  \\                 Redundant
  [                  Start of nested character class
    \\                 Redundant
  ]                  End of nested character class
  :;<>?,.            Any of those characters
  \\                 Redundant
  /@                 Any of those characters
  \\                 Redundant
  b                  That character
  \\                 Redundant
  r                  That character
  \\                 Redundant
  t                  That character
  \\                 Redundant
  Z                  That character
  \\                 Redundant
  %                  That character
  \\                 Redundant
  n                  That character
  \\                 Redundant
  0                  That character
  \\                 Redundant
  _                  That character
  \\                 Redundant
  '                  That character
  \\                 Redundant
  \"                 Unnecessary escape of "
  \\                 Redundant
  \\                 Redundant
]                  End of character class
$                  Match end of input

删除所有多余和不必要的部分，它与：

^[-!$%^&*()+|~=`\\#{}:;<>?,./@brtZ%n0_'"]$

其中，作为Java字符串文字是：

String regex = "^[-!$%^&*()+|~=`\\\\#{}:;<>?,./@brtZ%n0_'\"]$";

Java Regex格式

1 个答案: