[Java] HttpURLConnection을 이용하여 api 호출

public static String execute(String method, final String url, final JSONObject parameters) {
        HttpURLConnection connection = null;
        
        String result ="";
        int methodCase = 0;
        if(method.toUpperCase().equals("POST")) methodCase = 1;
        try {
            switch (methodCase) {
                case 0:
                    connection = openConnection(url.concat("?").concat(formEncode(parameters)));
                    connection.setRequestMethod("GET");
                    connection.setConnectTimeout(3000);
                    connection.connect();
                    break;
                case 1:
                    connection = openConnection(url);
                    connection.setRequestMethod("POST");
                    connection.setDoOutput(true);
                    connection.setRequestProperty("Content-Type", "application/json");
                    connection.setConnectTimeout(3000);
                    connection.connect();
                    final OutputStream out = connection.getOutputStream();
                    
                    out.write(parameters.toString().getBytes());
                    out.flush();
                    out.close();
                    break;
            }
            final int statusCode = connection.getResponseCode();
            if (statusCode / 100 != 2) {
                // 400, 401, 501
                result = "{\"error\":"+statusCode+"}";
            }else{
                result = readInputStream(connection.getInputStream());
            }
        } catch (IOException e) {
            Logger.getLogger( HttpJsonUtil.class ).error( "HttpJsonUtil.execute--Error : ", e);
            return result;
        } finally {
            if (connection != null) connection.disconnect();
        }
        
        return result;
    }

ex) class.execute("POST", "http://127.0.0.1:8080/test/test1", null)