例
String regex = '(\\{...\\})';
String str = '{aaa}日本語{bbb}さささささ{ccc}';
Matcher matcher=Pattern.compile(regex).matcher(str);
while(matcher.find()){
System.debug('#Matching string' + matcher.group());
}
System.debug('#####');
System.debug(matcher);
参考:
https://murashun.jp/article/programming/regular-expression.html#chapter-1
https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_classes_pattern_and_matcher_example.htm
https://qiita.com/piepie1231/items/1596488fde02dfb58699