从Restful Web服务异步访问数据

Question

I am writing an android application where all my data is expose using web service. I am writing a wrapper class to fetch data from the services called DataManager.

public class DataManager{

public DataManager (){}


public String getValue ()
{
    HttpClient client = new DefaultHttpClient();
    HttpGet get = new HttpGet ("some url");

    try 
    {
        HttpResponse response = client.execute(get);
        if (response.getStatusLine ().getStatusCode() == 200)
        {
            HttpEntity entity = response.getEntity ();
            String result = EntityUtils.toString(entity);
            return result;
        }
    } 
    catch (ClientProtocolException e) 
    {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    catch (IOException e) 
    {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return null;
}

}

When I call this method a RuntimeException is generated on the UI thread. How can I refactor this code and fetch the values from the webservice and return these values asynchronously. [NOTE] I am writing this for some team members so they can use it to get data from the service so I want it to be has easy has possible for them to use.

Answer 1

Use AsyncTask or IntentService . Doing networking (and in general lengthy operations) on UI thread is no-no on Android.

Here you got with AsyncTask fundamentals and some tutorials And here you got with IntentService fundamentals and tutorials

I'd use AsyncTask myself (IntentService's jobs are queued), but be aware about change in the way it is handled in newer APIs . Not a big deal (just a few more code lines), though

Answer 2

我建议尝试一下David Chandler的Android 基本HTTP客户端库。

Answer 3

Best way to do this is to use an IntentService. That gives you a background thread and a way to pass it a URL. Depending on how much data you have, you can either dump it into a local file or store it in a database.

If you do the database route, you can load the data asynchronously in an Activity using AsyncTaskLoader, or do full access using AsyncTask. And, with some extra overhead but much more simple coding, you can stick the data in a ContentProvider and then use a CursorLoader in your Activity.

Above all, never do network operations or database operations on the UI thread. Use your Activity as a "presenter" (an intelligent "view") and put all the controller and model stuff in the background.