HttpClient request payload post请求（传输的数据为json）

private static String postJsonFile1(String url, Map params, Map headers, int connectTimeout, int readTimeout, String encoding, HttpUtil.HttpMethod method) {

        JSONObject jsonObject = JSONObject.fromObject(params);
        URL uUrl = null;
        HttpURLConnection conn = null;
        BufferedWriter out = null;
        BufferedReader in = null;
        try {
            //创建和初始化连接
            uUrl = new URL(url);
            conn = (HttpURLConnection) uUrl.openConnection();
            conn.setRequestProperty("content-type", "application/json");
            conn.setRequestMethod(method.toString());
            conn.setDoOutput(true);
            conn.setDoInput(true);
            //设置连接超时时间
            conn.setConnectTimeout(connectTimeout);
            //设置读取超时时间
            conn.setReadTimeout(readTimeout);
            //指定请求header参数
            if (headers != null && headers.size() > 0) {
                Set headerSet = headers.keySet();
                for (String key : headerSet) {
                    conn.setRequestProperty(key, headers.get(key));
                }
            }

            out = new BufferedWriter(new OutputStreamWriter(conn.getOutputStream(), encoding));
            out.write(jsonObject.toString());
            out.flush();

            //接收返回结果
            StringBuilder result = new StringBuilder();
            in = new BufferedReader(new InputStreamReader(conn.getInputStream(), encoding));
            if (in != null) {
                String line = "";
                while ((line = in.readLine()) != null) {
                    result.append(line);
                }
            }
            return result.toString();

        } catch (Exception e) {
            logger.error("调用接口[" + url + "]失败！请求URL：" + url + "，参数：" + jsonObject, e);
            System.out.println("发送POST请求出现异常！" + e);
            //处理错误流，提高http连接被重用的几率
            try {
                byte[] buf = new byte[100];
                InputStream es = conn.getErrorStream();
                if (es != null) {
                    while (es.read(buf) > 0) {
                        ;
                    }
                    es.close();
                }
            } catch (Exception e1) {
                e1.printStackTrace();
            }
        } finally {
            try {
                if (out != null) {
                    out.close();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            try {
                if (in != null) {
                    in.close();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
            //关闭连接
            if (conn != null) {
                conn.disconnect();
            }
        }

        return null;
    }