根据参数名获取路径中的参数值 JAVA

    public static String getParamByUrl(String url, String name) {
        url += "&";
        String pattern = "(\?|&){1}#{0,1}" + name + "=[a-zA-Z0-9]*(&{1})";
        Pattern r = Pattern.compile(pattern);
        Matcher matcher = r.matcher(url);
        if (matcher.find()) {
            return matcher.group(0).split("=")[1].replace("&", "");
        } else {
            return "";
        }
    }

public static void main(String[] args) throws MalformedURLException {
        String str = "http://localhost:8888/s/71c37937be4c4a01a3b5fc88a5ca2bf2?ext=1";
        URL url = new URL(str);
        System.out.println("URL 为：" + url.toString());
        System.out.println("协议为：" + url.getProtocol());
        System.out.println("验证信息：" + url.getAuthority());
        System.out.println("文件名及请求参数：" + url.getFile());
        System.out.println("主机名：" + url.getHost());
        System.out.println("路径：" + url.getPath());
        System.out.println("端口：" + url.getPort());
        System.out.println("默认端口：" + url.getDefaultPort());
        System.out.println("请求参数：" + url.getQuery());
        System.out.println("定位位置：" + url.getRef());


        System.out.println(getParamByUrl(str,"ext"));
    }

结果：