asynchronous http query for android

Surprisingly i found not as much information on it as i expected. So i had to make my own class for async requests.


Here is how it can be used:

new Service("http://localhost/list.php").query("limit=10",new android.os.Handler.Handler(), new ServiceHandler() {
    public void notify(boolean success, String response) {
        if (success) txtResult.setText((CharSequence)response);
    }
}});

Here it is:

//ok, just a callback
public abstract interface ServiceHandler {
 public abstract void notify(boolean success, String response);
}

public class Service {
   private String url;
   public Service(String url) {
       this.url = url;
   }
   public void query(String rawdata,final Handler handler, final ServiceHandler serviceHandler) {
       HttpClient httpClient = new DefaultHttpClient();
       HttpConnectionParams.setConnectionTimeout(httpClient.getParams(), 25000);
       HttpPost httpPost = new HttpPost(this.url);
       try {
           httpPost.setEntity(new StringEntity(rawdata));
       } catch (Exception e) {
           serviceHandler.notify(false, (String)null);
       }

       //now let's run query itself in another thread
       new Thread(new ServiceRunner(httpClient,httpPost,new ServiceHandler() {
           public void notify(final boolean success, final String response) {
               //we've recieved response, but we need to pass it to the UI thread
               handler.post(new Runnable() {
                   public void run() {
                       serviceHandler.notify(success, response);
                   }
               });          
           }
       })).start();
   }

   //this class does all dirty work: it connects, sends post data and reads response
   private class ServiceRunner implements Runnable {
       private HttpClient httpClient;
       private HttpPost httpPost;
       private ServiceHandler handler;
       public ServiceRunner(HttpClient httpClient,HttpPost httpPost,ServiceHandler serviceHandler) {
           this.httpClient = httpClient;
           this.httpPost = httpPost;
           this.handler = serviceHandler;
       }
       public void run() {
           try {
               HttpResponse response = null;
               response = httpClient.execute(httpPost);
               processEntity(handler, response.getEntity());
           } catch (ClientProtocolException e) {
               handler.notify(false, null);
           } catch (IOException e) {
               handler.notify(false, null);
           }
       }
   }

   //this method reads response line by line
   private void processEntity(ServiceHandler handler,HttpEntity entity) throws IllegalStateException,IOException {
       BufferedReader br = new BufferedReader(new InputStreamReader(entity.getContent()));
       String line = "";
       StringBuilder sb = new StringBuilder();
       while ((line = br.readLine()) != null) sb = sb.append(line).append("\n");
       handler.notify(true, sb.toString());
   }

}

If there will be at least a single person reading this post, i'll make a next post explaining how to use this class for JSON-serialized requests.