Java发送JSON形式的请求

public static String doPostRequest(String url, Map<String,String> header,
                                   JSONObject params, HttpEntity entity){

    String resultStr = "";
    if(StringUtils.isEmpty(url)){
        return resultStr;
    }
    CloseableHttpClient httpClient = null;
    CloseableHttpResponse httpResponse = null;

   try{
       httpClient = SSLClientCustom.getHttpClient();
       HttpPost httpPost = new HttpPost(url);
       if(!header.isEmpty()){
           for(Map.Entry<String,String> stringStringEntry : header.entrySet()){
               httpPost.setHeader(stringStringEntry.getKey(),stringStringEntry.getValue());
           }
       }

       if (!params.isEmpty()){
           StringEntity stringEntity = new StringEntity(params.toString(), "UTF-8");
           stringEntity.setContentEncoding("UTF-8");
           httpPost.setEntity(stringEntity);
       }
       if(entity != null){
           httpPost.setEntity(entity);
       }
       httpResponse = httpClient.execute(httpPost);
       int statusCode = httpResponse.getStatusLine().getStatusCode();
       if(statusCode == HttpStatus.SC_OK){
           HttpEntity httpResponseEntity = httpResponse.getEntity();
           resultStr = EntityUtils.toString(httpResponseEntity);
           logger.info("请求正常，请求地址：{},响应结果:{}",url,resultStr);
       }else {
           StringBuffer stringBuffer = new StringBuffer();
           HeaderIterator headerIterator = httpResponse.headerIterator();
           while (headerIterator.hasNext()){
               stringBuffer.append("\t"+headerIterator.next());
           }
           logger.info("异常信息:请求地址:{},响应状态:{},请求返回结果:{}",url,httpResponse.getStatusLine().getStatusCode(),stringBuffer);
       }

   }catch (Exception e){
       e.printStackTrace();
   }finally {
      try{
          httpResponse.close();
          httpClient.close();
      }catch (Exception e){
          e.printStackTrace();
      }
   }


return resultStr;

}