Android中的Http 500内部服务器错误

Android代码

class BirthdayTask extends AsyncTask<String, String, String>{

        @Override
        protected String doInBackground(String... uri) {
            HttpClient httpclient = new DefaultHttpClient();
            HttpResponse response;
            String responseString = null;
            try {
                System.out.println(uri[0]);
                response = httpclient.execute(new HttpGet(uri[0]));
                StatusLine statusLine = response.getStatusLine();
                if(statusLine.getStatusCode() == HttpStatus.SC_OK){
                    ByteArrayOutputStream out = new ByteArrayOutputStream();
                    response.getEntity().writeTo(out);
                    out.close();
                    responseString = out.toString();
                    System.out.println("responseString"+responseString);
                } else{
                    //Closes the connection.
                    response.getEntity().getContent().close();
                    throw new IOException(statusLine.getReasonPhrase());
                }
            } catch (ClientProtocolException e) {
                //TODO Handle problems..
            } catch (Exception e) {
                e.printStackTrace();
            }
            return responseString;
        }


        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);
            /* System.out.println(result);
            System.out.println(result);
            System.out.println(result);*/
        }

    }


 @RequestMapping(value="here is my url" ,method=RequestMethod.GET)
        public @ResponseBody String Test(HttpServletRequest req) {

            Gson gson = new Gson();

            Domain domain = (Domain)req.getSession().getAttribute("Domain");
            List<UserProfile> userProfiles = userProfileManager.getUpcomingBirthday(domain.getDomainId(),15);

            return gson.toJson(userProfiles);
        }

网络服务

这是我从浏览器中调用的Web服务，可以正常工作。但是，当我从Android拨打电话时，出现500个内部服务器错误。但是在服务器日志中我看不到任何错误。

怎么了？