Question

I am sending a JSONObject to my Webserver from an Android client using the code from this example. Reproducing code here

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;

int TIMEOUT_MILLISEC = 10000;  // = 10 seconds
HttpParams httpParams = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(httpParams, TIMEOUT_MILLISEC);
HttpConnectionParams.setSoTimeout(httpParams, TIMEOUT_MILLISEC);
HttpClient client = new DefaultHttpClient(httpParams);

HttpPost request = new HttpPost(serverUrl);
request.setEntity(new ByteArrayEntity(
    postMessage.toString().getBytes("UTF8")));
HttpResponse response = client.execute(request);

My Question

How to do best compression on JSONObject before sending it to server and how to decompress it on Server (I am using Java Servlets)?

Answer 1

According to this http://android-developers.blogspot.com/2011/09/androids-http-clients.html If you are using Gingerbread or later HttpURLConnection automatically adds gzip compression:

In Gingerbread, we added transparent response compression.
HttpURLConnection will automatically add this header to outgoing
requests, and handle the corresponding response:

Accept-Encoding: gzip

Your webserver would then need to handle gzip compression.

Edit:
Serve Gzipped content with Java Servlets

Edit 2:
Gzip compression using DefaultHttpClient Enabling GZip compression with HttpClient

private static final String HEADER_ACCEPT_ENCODING = "Accept-Encoding";
private static final String ENCODING_GZIP = "gzip";

final DefaultHttpClient client = new DefaultHttpClient(manager, parameters);

client.addRequestInterceptor(new HttpRequestInterceptor() {
  public void process(HttpRequest request, HttpContext context) {
    // Add header to accept gzip content
    if (!request.containsHeader(HEADER_ACCEPT_ENCODING)) {
      request.addHeader(HEADER_ACCEPT_ENCODING, ENCODING_GZIP);
    }
  }
});

client.addResponseInterceptor(new HttpResponseInterceptor() {
  public void process(HttpResponse response, HttpContext context) {
    // Inflate any responses compressed with gzip
    final HttpEntity entity = response.getEntity();
    final Header encoding = entity.getContentEncoding();
    if (encoding != null) {
      for (HeaderElement element : encoding.getElements()) {
        if (element.getName().equalsIgnoreCase(ENCODING_GZIP)) {
          response.setEntity(new InflatingEntity(response.getEntity()));
          break;
        }
      }
    }
  }
});

Edit 3:
Here is another Stackoverflow question regarding the gzipping of post contents GZip POST request with HTTPClient in Java. You will need to manually gzip the data before posting it, since the normal http/gzip operation is the server sending gzipped content to the client.