/**

     * <p>Desc:weChat构建请求参数</p>

     * <p>参数名ASCII码从小到大排序（字典序)</p>

     * @param params

     * @return

     */

    public static String buildBodyXml(Map<String,Object> params){

        SortedMap<String,Object> sort=new TreeMap<String,Object>(params);

         Set<String> keySet = sort.keySet();

        StringBuilder sb = new StringBuilder("<xml>");

        for (Object key : keySet) {

            sb.append(String.format("<%s>%s</%s>", key, params.get(key), key));

        }

        sb.append("</xml>");

        return sb.toString();

    }