httpPost方式访问url

public static String sendHttpPostIns(String url, String param) throws Exception {
    CloseableHttpClient httpclient = HttpClients.createDefault();
    CloseableHttpResponse httpResponse = null;
    try {
        HttpPost httpPost = new HttpPost(url);
        httpPost.setEntity(new StringEntity(param));
        //httpPost.setEntity(new StringEntity(param,"utf-8"));
        httpPost.addHeader("Content-type","application/json; charset=utf-8");
        httpPost.setHeader("Accept", "application/json");

        HttpEntity entity = httpclient.execute(httpPost).getEntity();

        if (entity == null) {
            return null;
        }
        String data = EntityUtils.toString(entity, Consts.UTF_8);
        if (StringUtil.isEmpty(data)) {
            return null;
        }
        return data;
    } catch (Exception e) {
        e.printStackTrace();
        throw new Exception(e);
    }finally {
        if(httpResponse!=null){
            httpResponse.close();
        }
        if(httpclient!=null){
            httpclient.close();
        }
    }
}