java – 如何在Android上建立异步URL连接？

我使用以下类连接到我的Web服务.我想让这个异步.我怎样才能做到这一点？

package org.stocktwits.Helper;

import java.io.bufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import org.apache.http.httpentity;
import org.apache.http.httpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.httpClient;
import org.apache.http.client.methods.httpGet;
import org.apache.http.impl.client.DefaulthttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import android.util.Log;

public class RestClient{

    private static String convertStreamToString(InputStream is) {
        /*
         * To convert the InputStream to String we use the BufferedReader.readLine()
         * method. We iterate until the BufferedReader return null which means
         * there's no more data to read. Each line will appended to a StringBuilder
         * and returned as String.
         */
        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        StringBuilder sb = new StringBuilder();

        String line = null;
        try {
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
        } catch (IOException E) {
            e.printStackTrace();
        } finally {
            try {
                is.close();
            } catch (IOException E) {
                e.printStackTrace();
            }
        }

        return sb.toString();
    }


    /* This is a test function which will connects to a given
     * rest service and prints it's response to Android Log with
     * labels "Praeda".
     */
    public static JSONObject connect(String url)
    {

        httpClient httpclient = new DefaulthttpClient();


        // Prepare a request object
        httpGet httpget = new httpGet(url); 

        // Execute the request
        httpResponse response;
        try {
            response = httpclient.execute(httpget);
            // Examine the response status
            Log.i("Praeda",response.getStatusLine().toString());

            // Get hold of the response entity
            httpentity entity = response.getEntity();

            if (entity != null) {

                // A Simple JSON Response Read
                InputStream instream = entity.getContent();
                String result= convertStreamToString(instream);

                // A Simple JSONObject Creation
                JSONObject json=new JSONObject(result);

                // Closing the input stream will trigger connection release
                instream.close();

                return json;
            }


        } catch (ClientProtocolException E) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException E) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (JSONException E) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return null;
    }

}