java 中 escaping 标记字符的正则表达式

Question

I have saved messages with markup. it is using just a few markup functionalities for markup like bold, italic, strikethrough and code. What I need now is to strip those messages from any kind of markup, except for when in code. For example:

**bold**  _italic_ ~strike~ `**code**`

would return:

bold italic strike **code**

I currently use regex like this one for bold:

\*\*([^*]*)\*\*(?=(?:[^`\\]*(?:\\.|`(?:[^`\\]*\\.)*[^`\\]*`))*[^`]*$)

to strip my message from the formatting, but I am having a problem with composite markups, where multiple formatting is applied to the string like bold and italic at the same time.

**_bold and italic_**

Is there any way to strip that kind of message and something that would simplify the regex I am using?

Answer 1

You can use

replaceAll("`([^`]*)`|(\\*\\*|[_~])((?:(?!\\2).)*)\\2", "$1$3")

See the regex demo . Details :

• `([^`]*)` - backtick, then any zero or more non-backtick chars (captured into Group 1) and then a backtick
• | - or
• (\*\*|[_~]) - Group 2: ** , _ or ~
• ((?:(?.\\2).)*) - Group 3: any char, zero or more occurrences but as many as possible that does not start with the char sequence captured into Group 2
• \2 - Group 2 value.

See the Java demo :

String s = "**bold**  _italic_ ~strike~ `**code**`";
String regex = "(?s)`([^`]*)`|(\\*\\*|[_~])((?:(?!\\2).)*)\\2";
System.out.println(s.replaceAll(regex, "$1$3")); 
// => bold  italic strike **code**