I am trying to send a multi part formdata post through my java code. Can someone tell me how to set Content Length in the following?? There seem to be headers involved when we use InputStreamBody which implements the ContentDescriptor interface. Doing a getContentLength on the InputStreamBody gives me -1 after i add the content. I subclassed it to give contentLength the length of my byte array but am not sure if other headers required by ContentDescriptor will be set for a proper POST.

HttpClient httpclient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(myURL);
ContentBody cb = new InputStreamBody(new ByteArrayInputStream(bytearray), myMimeType, filename);
//ContentBody cb = new ByteArrayBody(bytearray, myMimeType, filename);

MultipartEntity mpentity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE);
mpentity.addPart("key", new StringBody("SOME_KEY"));
mpentity.addPart("output", new StringBody("SOME_NAME"));
mpentity.addPart("content", cb);
httpPost.setEntity(mpentity);
HttpResponse response = httpclient.execute(httpPost);

HttpEntity resEntity = response.getEntity();