java正则，

    public static void main(String[] args) {        String s0 = "?pid=34";        String s1 = "?pid=34&pageNo=35";        String s2 = "?pid=56&pageNo=36&sid=23";                //XXXXXXXXXX 正则部分                System.out.println(s0);        //要求输出：?pid=34        System.out.println(s1);        //要求输出：?pid=34&        System.out.println(s2);        //要求输出：?pid=56&sid=23                        /*                      提供一个JavaScript的实现参考            var args = location.search;            var argName = 'pageNo';            var reg = new RegExp('([\?&]?)' + argName + '=[^&]*[&$]?', 'gi');            args = args.replace(reg,'$1');            alert(args);         */    }