Android AsyncTask connection refuses emulator + Mamp-Collection of common programming errors

I want to read JSon from a local web server in my android Application.

This is my code :

public class MainActivity extends Activity implements OnItemClickListener {

HttpClient client;
JSONObject json;

public final static String EXTRA_MESSAGE = "com.example.gestionformations.MESSAGE";
final static String URL = "http://10.0.2.2/apis/general/get_categories/";
final static String LOG = "gestionFormations.log";
ListView conferenceListe;
ListView coursListe;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    client = new DefaultHttpClient();
    Log.i(LOG,"Create");
    new Read().execute("libcategorie");
}

public JSONObject getCategories() throws ClientProtocolException, IOException, JSONException{
    StringBuilder url = new StringBuilder(URL);
    HttpGet get = new HttpGet(url.toString());
    HttpResponse r = client.execute(get);
    int status = r.getStatusLine().getStatusCode();
    if(status == 200){
        HttpEntity e = r.getEntity();
        String data = EntityUtils.toString(e);
        JSONArray catArray = new JSONArray(data);
        JSONObject lesCategories = catArray.getJSONObject(0);
        //Log.i(LOG,"JsonObject : "+ lesCategories.toString());
        return lesCategories;
    }else{
        Log.i(LOG,"Erreur getCategories");
        return null;
    }
}

public class Read extends AsyncTask{

    @Override
    protected String doInBackground(String... params) {
        try {
            json = getCategories();
            return json.getString(params[0]);
        } 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;
    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        Log.i(LOG,result);
    }

}
}

My Manifest.xml looks like this :