Map中的key值按字典排序，客户端发送http请求

/**
 * 获得参数格式化字符串
 * 参数名按字典排序，小写在后面
 */
private String getFormatParams(Map<String,String> params){
    List<Map.Entry<String, String>> infoIds = new ArrayList<Map.Entry<String, String>>(params.entrySet());
    Collections.sort(infoIds, new Comparator<Map.Entry<String, String>>() {
        public int compare(Map.Entry<String, String> arg0, Map.Entry<String, String> arg1) {
            return (arg0.getKey()).compareTo(arg1.getKey());
        }
    });
    String ret = "";

    for (Map.Entry<String, String> entry : infoIds) {
        ret += entry.getKey();
        ret += "=";
        ret += entry.getValue();
        ret += "&";
    }
    ret = ret.substring(0, ret.length() - 1);
    return ret;
}

/**
 * 发送http请求，返回响应数据
 * @param requestUrl
 * @return
 */
private String sendHttpRequest(String requestUrl){
    CloseableHttpClient httpCilent = HttpClients.createDefault();
    HttpGet httpGet = new HttpGet(requestUrl);
    String result = "";
    try {
        HttpResponse httpResponse = httpCilent.execute(httpGet);
        result = EntityUtils.toString(httpResponse.getEntity());//获得返回的结果
    } catch (IOException e) {
        e.printStackTrace();
    }finally {
        try {
            httpCilent.close();//释放资源
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return result;
}