Java 如何以json格式打印httpPost请求？

我正在使用ApacheHttpClient-post方法调用rest客户端API，但API给出了错误的响应，因此我想调试该方法并以json格式打印请求。 下面是我正在使用的代码-

    private String baseUrl = "myIPAddress";
    private HttpClient client = new DefaultHttpClient();
    HttpPost post = new HttpPost(baseUrl + "app/registration");
            try {
                String line = "";
                for (int rIndex = 0; rIndex < goodAuthenticationPairs.length; rIndex++) {
                    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(
                            1);
                    nameValuePairs.add(new BasicNameValuePair("email","myEmail@test.com"));
                    nameValuePairs.add(new BasicNameValuePair("password","myPassword"));
                    post.setEntity(new UrlEncodedFormEntity(nameValuePairs));
                    //post.setHeader("Content-type", "application/json");
                    System.out.println(post);
                    HttpResponse response = client.execute(post);
                    BufferedReader rd = new BufferedReader(new InputStreamReader(
                            response.getEntity().getContent()));
                    line = rd.readLine();
                    System.out.println(line);
                    JSONObject json = (JSONObject) new JSONParser().parse(line);
                    String actualResult = json.get("return_code").toString();

                    assertTrue("0".equals(actualResult));
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                client.getConnectionManager().shutdown();
            }

我得到了答案。 上面的代码正在发送内容类型为application/x-www-form-urlencoded的请求，但服务器API要求内容类型为application/json