code: public static String doPost(String url, Map<String, String> header, Map<String, String> param)
              throws KeyManagementException, NoSuchAlgorithmException, IOException {
  
          String result = null;
          HttpClient httpClient = new SSLClient();
          httpClient.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, Constant.DEFAULT_CONN_TIMEOUT);
          httpClient.getParams().setParameter(CoreConnectionPNames.SO_TIMEOUT, Constant.DEFAULT_READ_TIMEOUT);
          HttpPost httpPost = new HttpPost(url);
          // 设置Header
          if (header != null) {
              Set<String> keys = header.keySet();
              for (String key : keys) httpPost.setHeader(key, header.get(key));
          }
          //设置参数
          List<NameValuePair> list = new ArrayList<NameValuePair>();
          Iterator iterator = param.entrySet().iterator();
          while (iterator.hasNext()) {
              Entry<String, String> elem = (Entry<String, String>) iterator.next();
              list.add(new BasicNameValuePair(elem.getKey(), elem.getValue()));
          }
          if (list.size() > 0) {
              UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, Constant.DEFAULT_CHARSET);
              httpPost.setEntity(entity);
          }
          HttpResponse response = httpClient.execute(httpPost);
          if (response != null) {
              HttpEntity resEntity = response.getEntity();
              if (resEntity != null) {
                  result = EntityUtils.toString(resEntity, Constant.DEFAULT_CHARSET);
              }
          }
          return result;
      }
docs: POST方式向Http(s)提交数据并获取返回结果
  
  @param url    URL
  @param header Header
  @param param  参数（Map）
  
  @return 获取服务器数据
  
  @throws KeyManagementException [ellipsis]
  @throws NoSuchAlgorithmException [ellipsis]
  @throws IOException [ellipsis]