阿Pattern可以用标志进行编译，如果正则表达式被用作文字String，使用内联改性剂：
Pattern pattern = Pattern.compile("foo.",Pattern.CASE_INSENSITIVE| Pattern.DOTALL);
pattern.matcher("FOO\n").matches(); // 是真的。
/* Had the regex not been compiled case insensitively and singlelined,
* it would fail because FOO does not match /foo/ and \n (newline)
* does not match /./.
*/
Pattern anotherPattern = Pattern.compile("(?si)foo");
anotherPattern.matcher("FOO\n").matches(); // 是真的。
"foOt".replaceAll("(?si)foo", "ca"); // Returns "cat".