Android: HTTP communication should use "Accept-Encoding: gzip"

I've a HTTP communication to a webserver requesting JSON data. I'd like compress this data stream with Content-Encoding: gzip. Is there a way I can set Accept-Encoding: gzip in my HttpClient? The search for gzip in the Android References doesn't show up anything related to HTTP, as you can see here.

You should use http headers to indicate a connection can accept gzip encoded data, e.g:

HttpUriRequest request = new HttpGet(url);
request.addHeader("Accept-Encoding", "gzip");
// ...
httpClient.execute(request);

Check response for content encoding:

InputStream instream = response.getEntity().getContent();
Header contentEncoding = response.getFirstHeader("Content-Encoding");
if (contentEncoding != null && contentEncoding.getValue().equalsIgnoreCase("gzip")) {
    instream = new GZIPInputStream(instream);
}

If you're using API level 8 or above there's AndroidHttpClient.

It has helper methods like:

public static InputStream getUngzippedContent (HttpEntity entity)

and

public static void modifyRequestToAcceptGzipResponse (HttpRequest request)

leading to much more succinct code:

AndroidHttpClient.modifyRequestToAcceptGzipResponse( request );
HttpResponse response = client.execute( request );
InputStream inputStream = AndroidHttpClient.getUngzippedContent( response.getEntity() );

I think the sample of code at this link is more interesting: ClientGZipContentCompression.java

They are using HttpRequestInterceptor and HttpResponseInterceptor

Sample for request:

        httpclient.addRequestInterceptor(new HttpRequestInterceptor() {

            public void process(
                    final HttpRequest request,
                    final HttpContext context) throws HttpException, IOException {
                if (!request.containsHeader("Accept-Encoding")) {
                    request.addHeader("Accept-Encoding", "gzip");
                }
            }

        });

Sample for answer:

        httpclient.addResponseInterceptor(new HttpResponseInterceptor() {

            public void process(
                    final HttpResponse response,
                    final HttpContext context) throws HttpException, IOException {
                HttpEntity entity = response.getEntity();
                Header ceheader = entity.getContentEncoding();
                if (ceheader != null) {
                    HeaderElement[] codecs = ceheader.getElements();
                    for (int i = 0; i < codecs.length; i++) {
                        if (codecs[i].getName().equalsIgnoreCase("gzip")) {
                            response.setEntity(
                                    new GzipDecompressingEntity(response.getEntity()));
                            return;
                        }
                    }
                }
            }

        });

I haven't used GZip, but I would assume that you should use the input stream from your HttpURLConnection or HttpResponse as GZIPInputStream, and not some specific other class.

In my case it was like this:

URLConnection conn = ...;
InputStream instream = conn.getInputStream();
String encodingHeader = conn.getHeaderField("Content-Encoding");
if (encodingHeader != null && encodingHeader.toLowerCase().contains("gzip"))
{
	instream = new GZIPInputStream(instream);
}