ResponseCache put never called

Question

I am trying to cache images in an android app with this solution Android image caching. I have already implemented a specific ResponseCache and overriden the get and put methods.

Despite that, images are not properly cached. When I debug I can see that the put method of my ResponseCache implementation is never called. My get method is properly called each time a request is made but never is the put method. Nothing is never cached so it can't retrieve any file...

My request use HTTPS so i was wondering if caching the response was allowed or if i'll have to deal with requesting the server every time I want to display my images.

Here is the code :

public class ImageResponseCache extends ResponseCache {

    File cacheDir;

    public ImageResponseCache(File cacheDir) {
        super();
        this.cacheDir = cacheDir;
    }

    @Override
    public CacheResponse get(URI uri, String s,
    Map<String, List<String>> headers) throws IOException {
        final File file = new File(cacheDir, escape(uri.getPath()));
        if (file.exists()) {
            return new CacheResponse() {
                @Override
                public Map<String, List<String>> getHeaders()
                throws IOException {
                    return null;
                }

                @Override
                public InputStream getBody() throws IOException {
                    return new FileInputStream(file);
                }
            };
            } else {
            return null;
        }
    }

    @Override
    public CacheRequest put(URI uri, URLConnection urlConnection)
    throws IOException {
        Log.i("Image Response", "PUT");
        final File file = new File(cacheDir, escape(urlConnection.getURL()
        .getPath()));
        return new CacheRequest() {
            @Override
            public OutputStream getBody() throws IOException {
                return new FileOutputStream(file);
            }

            @Override
            public void abort() {
                file.delete();
            }
        };
    }

    private String escape(String url) {
        return url.replace("/", "-").replace(".", "-");
    }
}

Here is the function that request my images in an adapter:

private Bitmap requestImage(String file) {
    Bitmap bm = null;

    Log.d(TAG, "path: " + file);
    URL url = null;
    HttpURLConnection http = null;

    try {

        url = new URL(file);

        if (url.getProtocol().toLowerCase().equals("https")) {
            NetworkUtils.trustAllHosts();
            HttpsURLConnection https = (HttpsURLConnection) url
                    .openConnection();
            https.setHostnameVerifier(NetworkUtils.DO_NOT_VERIFY);
            http = https;
        } else {
            http = (HttpURLConnection) url.openConnection();
        }
        http.setUseCaches(true);

        ResponseCache.setDefault(new ImageResponseCache(
                ImageAdapter.this.mContext.getCacheDir()));

        http.setRequestProperty(
                "Authorization",
                "Basic "
                        + Base64.encodeToString(
                                (Constants.USER + ":" + Constants.PASSWORD)
                                        .getBytes(), Base64.NO_WRAP));

        http.setConnectTimeout(Constants.TIME_OUT);

        bm = BitmapFactory.decodeStream((InputStream) http.getContent());

    } catch (Exception e) {
        Log.e(TAG, e.getMessage(), e);
    }

    return bm;
}

Does anyone know what could be wrong?