httpClient发送Json请求，结果返回Json.

public static JSONObject post(String url,JSONObject json){
        HttpClient client = new DefaultHttpClient();
        HttpPost post = new HttpPost(url);
        JSONObject response = null;
        try {
            StringEntity s = new StringEntity(json.toString());
            s.setContentEncoding("UTF-8");
            s.setContentType("application/json");
            post.setEntity(s);

            HttpResponse res = client.execute(post);
            if(res.getStatusLine().getStatusCode() == HttpStatus.OK.value()){
                HttpEntity entity = res.getEntity();
                String charset = EntityUtils.getContentCharSet(entity);
                response = new JSONObject(new JSONTokener(new InputStreamReader(entity.getContent(),charset)));
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
        return response;
    }