java 正则根据指定key取value

public static void main(String[] args) {
    String key = "姓名";
    String orgin = "姓名:王五,";
    String  reg = key + ":([^,]+),";
    Pattern p = Pattern.compile(reg);
    Matcher matcher = p.matcher(orgin);
    if (matcher.find()) {
        System.out.println(matcher.group(1));
    } else {
        System.out.println("null");
    }
}