Can not read request body from servlet

Question

This is my controller code:

@RequestMapping(value = "/test", method = RequestMethod.POST)
    public @ResponseBody String testPost(@RequestParam(value = "testParam") int testParam, HttpServletRequest request) {    
        try {
            System.out.println("body is "+BufferUtil.getHttpRequestBody(request));
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }

BufferUtil.getHttpRequestBody(request) is

public static String getHttpRequestBody(HttpServletRequest request)
            throws IOException {
        Scanner s = null;
        try {
            s = new Scanner(request.getInputStream(), "UTF-8")
                    .useDelimiter("\\A");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return s.hasNext() ? s.next() : "";
    }

This is the code to use to test controller:

 HTTPUtil.sendRequest("http://localhost:8081/es09android/test?testParam=1", "POST", "hello world");

sendRequest() implementation:

public static HttpResponse sendRequest(String url, String method,
                                           String data) {
        DataOutputStream wr = null;
        BufferedReader in = null;
        HttpResponse httpResponse = new HttpResponse();
        try {
            URL obj = new URL(url);
            HttpURLConnection con = (HttpURLConnection) obj.openConnection();
            con.setRequestMethod(method);
            con.setRequestProperty("User-Agent", USER_AGENT);
            con.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
            con.setDoOutput(true);
            if (data != null) {
                wr = new DataOutputStream(con.getOutputStream());
                wr.write(data.getBytes(UTF8_CHARSET));
            }
            int responseCode = con.getResponseCode();
            httpResponse.setResponseCode(responseCode);
            if (httpResponse.isOk()) {
                in = new BufferedReader(new InputStreamReader(
                        con.getInputStream(), "UTF8"));
                String inputLine;
                StringBuffer response = new StringBuffer();
                while ((inputLine = in.readLine()) != null) {
                    response.append(inputLine);
                }
                httpResponse.setData(response.toString());
            }
            return httpResponse;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        } finally {
            if (wr != null) {
                try {
                    wr.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

If I run it and then send request, controller will not print body. But if remove @RequestParam(value = "testParam") from the controller, everything will be ok. What is wrong?

Answer 1

Edited after more information provided in comments below

I assume what's hapening is that s.hasNext() is returning false , because you're at the end of the request's InputStream. This is as designed, you can only read the InputStream once.

This question has a good example of a way you can cache the request to read it more than once.
This question describes a way you can use Spring to log the entire request, which seems to be what your aim is in your question.