How to stream a JSON object to a HttpURLConnection POST request

Question

I can not see what is wrong with this code:

JSONObject msg;  //passed in as a parameter to this method

HttpURLConnection httpCon = (HttpURLConnection) url.openConnection();
httpCon.setDoOutput(true);
httpCon.setDoInput(true);
httpCon.setUseCaches(false);
httpCon.setRequestProperty( "Content-Type", "application/json" );
httpCon.setRequestProperty("Accept", "application/json");
httpCon.setRequestMethod("POST");
OutputStream os = httpCon.getOutputStream();
OutputStreamWriter osw = new OutputStreamWriter(os, "UTF-8");
msg.write(osw);
osw.flush();
osw.close();    
os.close();     //probably overkill

On the server, I am getting no post content at all, a zero length string.

Answer 1

Try

...
httpCon.setRequestMethod("POST");
httpCon.connect(); // Note the connect() here
...
OutputStream os = httpCon.getOutputStream();
OutputStreamWriter osw = new OutputStreamWriter(os, "UTF-8");
...    
osw.write(msg.toString());
osw.flush();
osw.close();

to send data.

to retrieve data try:

BufferedReader br = new BufferedReader(new InputStreamReader( httpCon.getInputStream(),"utf-8"));
String line = null;
while ((line = br.readLine()) != null) {
    sb.append(line + "\n");
}
br.close();
System.out.println(""+sb.toString());