正则表达式实现分组查找变量替换

/**
 * Java code
 * 替换 $<> 内的变量，把变量变为大写
 */
@Test
public void test() {
    String data = "Hello $<finna> , You are my $<love> .";
    String regex = "\\$<(.+?)>";// 正则
    Pattern pattern = Pattern.compile(regex);
    Matcher matcher = pattern.matcher(data);
    StringBuffer msg = new StringBuffer();
    while (matcher.find()) {
        String key = matcher.group(1);//group() or group(0) 代表整个匹配串，如 $<finna>
        matcher.appendReplacement(msg, key.toUpperCase());
    }
    matcher.appendTail(msg);
    System.out.println(msg);//Hello FINNA , You are my LOVE .
}