在 Spring Controller 方法中未获取 JSON 值

Question

我需要将一些数据从我的 Android 设备发送到我的服务器。我正在通过 JSON 执行此操作。我已经在 Android 上实现了 JSON 帖子，并且我正在尝试在服务器端进行映射以检索该数据。我的问题是我不断得到一个空字符串。

用于发送 JSON 的 Android 方法：

private void sendJson(final String json, final String URL) {
    Thread t = new Thread(){
    public void run() {
            Looper.prepare(); //For Preparing Message Pool for the child Thread
            HttpClient client = new DefaultHttpClient();
            HttpConnectionParams.setConnectionTimeout(client.getParams(), 10000); //Timeout Limit
            try{
                HttpPost post = new HttpPost(URL);
                StringEntity se = new StringEntity(json);  
                se.setContentType(new BasicHeader(HTTP.CONTENT_TYPE, "application/json"));
                post.setEntity(se);
                client.execute(post);
            }
            catch(Exception e){
                e.printStackTrace();
            }
            Looper.loop(); //Loop in the message queue
        }
    };
    t.start();      
}

服务器端方法：

@RequestMapping(value = "/getLatestCalls", method = RequestMethod.POST)
public void getData(@ModelAttribute String json){
    //... do something 
}

问题是，在这种方法中，我的 json 字符串每次都是“”。我也尝试过使用@RequestParam，但它不再进入该方法。我也试过@ModelAttribute("json")。

有人可以在这里给我一点启发吗？提前谢谢你。

Answer 1

这是解决方案，效果很好。

服务器端

@Controller
    public class DataCollector {

        @RequestMapping(value = "/clientdatacollector", method = RequestMethod.POST)
        public @ResponseBody
        void abc(Writer writer, @RequestParam("gpsdata") String gpsJSON) {



            try {
                // here is your jsonstring ;)
                writer.write(gpsJSON.toString());

            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }

    }

---

客户端

 public static void httptest() {
            ArrayList<TravellingData> tdArray = new ArrayList<TravellingData>();
            Gson gson = new Gson();
            String jsonString = "";
            for (int i = 0; i < 1; i++) {
                tdArray.add(ObjectCreater.createMockTravellingDataObject());
            }

            jsonString = gson.toJson(tdArray);

            HttpClient client = new DefaultHttpClient();

            HttpPost post = null;
            try {
                post = new HttpPost(
                        "http://localhost:8080/uygulama/clientdatacollector");
            } catch (URISyntaxException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
            try {
                List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(1);
                nameValuePairs.add(new BasicNameValuePair("gpsdata", jsonString));
                post.setEntity(new UrlEncodedFormEntity(nameValuePairs));

                HttpResponse response = null;
                try {
                    response = client.execute(post);
                } catch (HttpException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                BufferedReader rd = new BufferedReader(new InputStreamReader(
                        response.getEntity().getContent()));
                String line = "";
                while ((line = rd.readLine()) != null) {
                    System.out.println(line);
                }

            } catch (IOException e) {
                e.printStackTrace();
            }

        }

---

Answer 2

尝试使用@RequestBody。它应该工作。