java 解析截取字符串中部分字符

String s = "{\"request_id\":\"20005508\",\"ext_data\":171,}";

Pattern p = Pattern.compile("(\"request_id\"|\"requestId\")\\s*:([^,}]*)[},]");
Matcher m = p.matcher(s);
if (m.find()) {
   System.out.println(m.group(2));
}