public static final char UNDERLINE='_';

    public static String camelToUnderline(String param){

        if (param==null||"".equals(param.trim())){

            return "";

        }

        int len=param.length();

        StringBuilder sb=new StringBuilder(len);

        for (int i = 0; i < len; i++) {

            char c=param.charAt(i);

            if (Character.isUpperCase(c)){

                sb.append(UNDERLINE);

                sb.append(Character.toLowerCase(c));

            }else{

                sb.append(c);

            }

        }

        return sb.toString();

    }

    public static String underlineToCamel(String param){

        if (param==null||"".equals(param.trim())){

            return "";

        }

        int len=param.length();

        StringBuilder sb=new StringBuilder(len);

        for (int i = 0; i < len; i++) {

            char c=param.charAt(i);

            if (c==UNDERLINE){

               if (++i<len){

                   sb.append(Character.toUpperCase(param.charAt(i)));

               }

            }else{

                sb.append(c);

            }

        }

        return sb.toString();

    }

    public static String underlineToCamel2(String param){

        if (param==null||"".equals(param.trim())){

            return "";

        }

        StringBuilder sb=new StringBuilder(param);

        Matcher mc= Pattern.compile("_").matcher(param);

        int i=0;

        while (mc.find()){

            int position=mc.end()-(i++);

            //String.valueOf(Character.toUpperCase(sb.charAt(position)));

            sb.replace(position-1,position+1,sb.substring(position,position+1).toUpperCase());

        }

        return sb.toString();

    }

    public static void main(String[] args) {

    }