/**
                     * 签名的参数名
                     */
                    private static final String SIGN_PARAM = "user_sign";
                    /**
                     * 渠道的参数名
                     */
                    private static final String CHANNEL_PARAM = "sendposition";

                    public void sendMessage(String mobile, String content) {
                        logger.debug("apply to send message, mobile : " + mobile + ", content : " + content);
                        String ip = this.randomIp();
                        try {     //empty block
                            Map<String, Object> map = new HashMap<>();
                            map.put("method","sendIntegralWall");  // what is it?
                            map.put("modetype",0);                 // what is it?
                            map.put("linkUrl","");                 // what is it? empty param will be removed
                            map.put("sendposition", productId);    // what is it? use your constant CHANNEL_PARAM
                            map.put("phone",mobile);
                            map.put("title", encodeChinese("短信发送"));
                            map.put("content", encodeChinese(content));
                            map.put("pageurl","");
                            map.put("userid","");
                            map.put("msgid","");     // what is it?
                            map.put("vericode","");  // what is it?
                            map.put("sign","");
                            map.put("ip", ip);
                            map.put("timestamp", System.currentTimeMillis());
                            map.put(SIGN_PARAM, this.sign(map));

                            StringBuilder sb = new StringBuilder(sendSmsUrl).append("?");
                            for(Map.Entry<String, Object> entry : map.entrySet()){
                                sb.append(entry.getKey()).append("=")
                                        .append(entry.getValue() == null ? "" : String.valueOf(entry.getValue()))
                                        .append("&");
                            }

                            sb.deleteCharAt(sb.length() - 1);

                            String url = sb.toString();
                            logger.debug("send message url : " + url);
                            String response = restTemplate.getForObject(url, String.class);  //restTemplate.getForObject(url, Map.class);
                            logger.info("send message, response : " + response);

                            Map<String, String> result = JsonUtil.fromJson(response, Map.class); // not needed
                            if(!"200".equals(result.get("code"))){
                                throw new RuntimeException("send sms error ! response : " + response);
                            }
                        } finally {  //empty block

                        }
                    }

                    public String sign(Map<String, Object> params){
                        if(params == null || params.size() == 0){
                            return null;
                        }

                        Object channel = String.valueOf(params.get(CHANNEL_PARAM));
                        if(channel == null)   // will be never null: String.valueOf(null) == "null"
                            return null;

                        params.remove(SIGN_PARAM);  // params.get(SIGN_PARAM) always null
                        List<String> paramNames = new ArrayList<>(params.keySet());
                        Collections.sort(paramNames);

                        StringBuilder sb = new StringBuilder();
                        for(String paramName : paramNames){
                            Object obj = params.get(paramName);
                            sb.append(paramName).append("=").append(obj == null ? "" : String.valueOf(obj)).append("&");
                        }

                        if(sb.length() > 0)
                            sb.deleteCharAt(sb.length() - 1);

                        return EncryptUtil.HMAC_SHA1(sb.toString(), key);
                    }

                    private String randomIp(){
                        StringBuilder sb = new StringBuilder();
                        for(int i = 0; i < 4; i++){
                            sb.append(random.nextInt(255)).append("."); // not valid ip,  Class A addresses have range from 1-126 in the first octet
                        }

                        return sb.deleteCharAt(sb.length() - 1).toString();
                    }
                }