Question

I had seen a few examples in Android implement maybeCreateHttpClient(), especially in Google sample, which it does is to check if HttpClient object is instantiated, if not, instantiate it, and reuse it.

Why this approach? Is creating new HttpClient expensive?

Answer 1

Use a connection pool (eg. ThreadSafeClientConnManager) to manage your clients.

HttpParams params = new BasicHttpParams();
HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);
HttpProtocolParams.setContentCharset(params, HTTP.DEFAULT_CONTENT_CHARSET);
HttpProtocolParams.setUseExpectContinue(params, true);

SchemeRegistry registry = new SchemeRegistry();
registry.register(new Scheme("http", PlainSocketFactory.getSocketFactory(), 80));
registry.register(new Scheme("https", SSLSocketFactory.getSocketFactory(), 443));

ClientConnectionManager connman = new ThreadSafeClientConnManager(params, registry);
client = new DefaultHttpClient(connman, params);

client is a singleton object which can be reused, to fire a request:

HttpResponse response = client.execute(new HttpGet(URL));