java正则忽略大小写

Java的正则表达式支持在正则中直接添加修饰符，以调整正则匹配的模式：

You can add the mode modifiers to the start of the regex. To specify multiple modes, simply put them together as in (?ismx).

• (?i) makes the regex case insensitive.
• (?s) for “single line mode” makes the dot match all characters, including line breaks.
• (?m) for “multi-line mode” makes the caret and dollar match at the start and end of each line in the subject string.

——Regular expressions in Java - Tutorial

常见的场景如：在SQL语句中对关键字的大小写并不敏感，匹配、替换时需注意：

• 判断语句中是否存在limit语法

  1 2	String sql = "select * from some_table limit 1000"; Boolean limited = sql.matches(".*(?i:limit) +[0-9]+.*");

• 对语句中的limit进行替换

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  Integer defaultLimit = 10; String sql = "select * from some_table limit 1000"; Boolean limited = sql.matches(".*(?i:limit) +[0-9]+.*"); if (limited) { sql = sql.replaceAll("(?i)limit +[0-9]+", String.format("limit %d", defaultLimit)); }