Google reCatpcha: validate user response in the server side with Java

Question

I am trying to implement Google reCAPTCHA as shown in https://developers.google.com/recaptcha/docs/verify and Google reCAPTCHA: how to get user response and validate in the server side, but I can't get the success field in the response.

I don't know if the problem is in the request or parsing the response, here is my code:

public Resolution contact(){
    String charset = java.nio.charset.StandardCharsets.UTF_8.name();
    try {
        String reCaptcha = context.getRequest().getParameter("g-recaptcha-response");
        String urlReCaptcha = String.format("https://www.google.com/recaptcha/api/siteverify?secret=%s&response=%s&remoteip=%s" 
            , URLEncoder.encode(mySecretKey,charset)
            , URLEncoder.encode(reCaptcha,charset)
            , URLEncoder.encode(context.getRequest().getHeader("X-FORWARDED-FOR")!=null?context.getRequest().getHeader("X-FORWARDED-FOR"):context.getRequest().getRemoteAddr(),charset));
        URLConnection connection;
        connection = new URL(urlReCaptcha).openConnection();
        InputStream response = connection.getInputStream();
        JSONObject json = new JSONObject(response);
        String success = json.get("success").toString();
    } catch (MalformedURLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return new ForwardResolution(VIEW_SUCCESS);
}

JSONObject is from https://github.com/douglascrockford/JSON-java, json is always empty, but I can't find success field in response InputStream, so I don't know where is the bug.

I'am using stripes framework, the JSP code is:

    <stripes:form beanclass="es.package.ContactActionBean">
        <fieldset class="form-group">
            <!-- Some fields -->
            <input type="submit" name="contact" value="SEND"  class="btn btn-success btn-sm"/>
        </fieldset>
        <div class="g-recaptcha" data-sitekey="my_public_key"></div>
    </stripes:form>

Any suggestions will be appreciated.

score 0 · Answer 1 · answered Feb 02 '15 at 09:38

Ains, it's enough to take the string from the InputStream and then instantiate the JSONObject:

        ...
        InputStream response = connection.getInputStream();
        // Take the string, Plain old JDK4 style
        StringBuilder inputStringBuilder = new StringBuilder();
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(response, "UTF-8"));
        String line = bufferedReader.readLine();
        while(line != null){
            inputStringBuilder.append(line);
            inputStringBuilder.append('\n');
            line = bufferedReader.readLine();
        }
        JSONObject json = new JSONObject(inputStringBuilder.toString());
        ...

You should fix this code. If we're not calling `readLine` method again, it might be an endless loop because the value for variable `line` never be null. — Piyush Pranjal, Jul 11 '22 at 07:43

Google reCatpcha: validate user response in the server side with Java

1 Answers1