从Java HTTPUrlConnection发送JSON，但是$ _POST变量在PHP中是否为空？

Question

I'm writing an Android app and I want to send some JSON data to a PHP server. The POST request does go to the server but in my server.php script I check the $_POST variable and it is empty. TCP/IP monitor is not in Eclipse ADT and wireshark doesn't show localhost request so I can't see what is actually being sent. So does anyone have an idea what is being sent and how I can access it in PHP? Or have I made a mistake in the code somewhere?

   JSONObject json = new JSONObject();

    try {
        json.put("dog", "cat");
    } catch (JSONException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

    HttpURLConnection urlConnection = null;
    try {
        URL url = new URL("http://10.0.2.2/server.php");
        urlConnection = (HttpURLConnection)url.openConnection();
        urlConnection.setRequestProperty("Content-Type", "application/json");
        urlConnection.setRequestProperty("Accept", "application/json");
        urlConnection.setRequestMethod("POST");         
        urlConnection.setDoOutput(true);
        OutputStreamWriter os = new OutputStreamWriter(urlConnection.getOutputStream(), "UTF-8");
        os.write(json.toString());
        os.close();
    }

Answer 1

try it.

JSONObject json = new JSONObject();

    try {
        json.put("dog", "cat");
    } catch (JSONException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

HttpClient localDefaultHttpClient=new DefaultHttpClient();
        HttpPost lotlisting = new HttpPost("http://10.0.2.2/server.php");
        ArrayList localArrayList = new ArrayList();
        localArrayList.add(new BasicNameValuePair("json",json.toString()));
        try {
            lotlisting.setEntity(new UrlEncodedFormEntity(localArrayList));
            String str = EntityUtils.toString(localDefaultHttpClient.execute(lotlisting).getEntity());

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

you will get the output in str variable;

Answer 2

I think is missing the flush Try os.flush(); after os.write(..)

Answer 3

Don't use $_POST. Do something like this on user server

    $json = file_get_contents('php://input');
    $animals= json_decode($json,true);

    //you can do 
    echo $animals['dog'];