http통신
POST 방식
HttpClient httpClient = HttpClientBuilder.create().build();
HttpPost httpPost = new HttpPost(Url);
(파라미터로 담을 데이터 구성)
String jsonStr = mapper.writeValueAsString(params);
httpPost.setHeader("Content-Type", "application/json");
StringEntity params = new StringEntity(jsonStr);
httpPost.setEntity(params);
HttpResponse response = httpClient.execute(httpPost);
repsonse.close();
httpClient.close();