格式化数据保留两位小数，输入格式为 ：xxx,xx,,,,x,,(x为浮点数)

/**
     * 格式化字符串
     */
    static String dataFormat(String data){
        String formatedData = "";
        // 浮点数正则表达式
        Pattern pattern = Pattern.compile("^(-?\\d+)(\\.\\d+)?$");
        if(data == null) return null;
        else {
            if(data.equals("")) formatedData = "";
            else if(!data.contains(",")){
                formatedData += new BigDecimal(data).setScale(2, BigDecimal.ROUND_HALF_UP);
            } else{
                while(data.length() != 0){
                    int position = data.indexOf(",");
                    if(data.indexOf(",") != -1){
                        String tempString = data.substring(0, position);
                        if(pattern.matcher(tempString).matches() ){
                            formatedData += new BigDecimal(tempString).setScale(2, BigDecimal.ROUND_HALF_UP);
                            formatedData += ",";
                            data = data.substring(position + 1);
                        }else if (tempString.equals("")) {
                            formatedData += ",";
                            data = data.substring(position + 1);
                        }else{
                            System.out.println("数据格式不正确");
                            return "";
                        }
                    }
                }
            }
        }
        return formatedData;
    }