ImageView Glitching AsyncTask

Question

我使用asyncTask从服务器中提取图像并在imageViews上绘制它们。问题是图像有时会被“洗牌”，并且需要几秒钟来部署正确的图像。而且它也会变得迟钝。有没有更简单的方法呢？我做错了吗？

 class JSONAsyncTask extends AsyncTask<String, Void, Boolean> {

    ProgressDialog dialog;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        dialog = new ProgressDialog(RecipeActivity.this);
        dialog.setMessage("Loading, please wait");
        dialog.setTitle("Connecting to server");
        dialog.show();
        dialog.setCancelable(false);
    }


    @Override
    protected Boolean doInBackground(String... urls) {
        try {

            //------------------>>
            HttpGet httppost = new HttpGet(urls[0]);
            HttpClient httpclient = new DefaultHttpClient();
            HttpResponse response = httpclient.execute(httppost);

            // StatusLine stat = response.getStatusLine();
            int status = response.getStatusLine().getStatusCode();

            if (status == 200) {
                HttpEntity entity = response.getEntity();
                String data = EntityUtils.toString(entity);


                //JSONObject jsono = new JSONObject(data);
                //JSONArray array = jsono.getJSONArray("recepies");
                JSONArray array = new JSONArray(data);

                for (int i = 0; i < array.length(); i++) {
                    JSONObject object = array.getJSONObject(i);

                    Recepies rec = new Recepies();

                    rec.setName(object.getString("name"));

                    rec.setPciture(object.getString("picture"));

                    receptis.add(rec);
                }
                return true;
            }

            //------------------>>

        } catch (ParseException e1) {
            e1.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return false;
    }

    protected void onPostExecute(Boolean result) {
        dialog.cancel();
        adapter.notifyDataSetChanged();
        if (result == false)
            Toast.makeText(getApplicationContext(), "Unable to fetch data from server", Toast.LENGTH_LONG).show();

    }
}

这是MainActivity：

ArrayList<Recepies> recepies;
String nameRecepie, ingredients, priprema, picture;
Toolbar toolbar;

RecipesAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.recipes_activity);
    toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    setTitle("Dog recepies");
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);


    receptis = new ArrayList<Recepti>();
    new JSONAsyncTask().execute("url");

    ListView listview = (ListView) findViewById(R.id.list);
    adapter = new RecipesAdapter(getApplicationContext(), R.layout.row, receptis);

    listview.setAdapter(adapter); //onclick listener ->

和我的Adapter类

public class RecipesAdapter extends ArrayAdapter<Recepti> {
ArrayList<Recepti> receptisList;
LayoutInflater vi;
int Resource;
ViewHolder holder;

public RecipesAdapter(Context context, int resource, ArrayList<Recepti> objects) {
    super(context, resource, objects);
    vi = (LayoutInflater) context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    Resource = resource;
    receptisList = objects;
}


@Override
public View getView(int position, View convertView, ViewGroup parent) {
    // convert view = design
    View v = convertView;
    if (v == null) {
        holder = new ViewHolder();
        v = vi.inflate(Resource, null);
        holder.imageview = (ImageView) v.findViewById(R.id.ivImage);
        holder.tvName = (TextView) v.findViewById(R.id.tvName);

        v.setTag(holder);
    } else {
        holder = (ViewHolder) v.getTag();
    }
    new DownloadImageTask(holder.imageview).execute(receptisList.get(position).getSlika());
    holder.tvName.setText(receptisList.get(position).getNaziv());
    return v;

}

static class ViewHolder {
    public TextView tvName;
    public ImageView imageview;

}

protected class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
    ImageView bmImage;

    public DownloadImageTask(ImageView bmImage) {
        this.bmImage = bmImage;
    }

    protected Bitmap doInBackground(String... urls) {
        String urldisplay = urls[0];
        Bitmap mIcon11 = null;
        try {
            InputStream in = new java.net.URL(urldisplay).openStream();
            mIcon11 = BitmapFactory.decodeStream(in);
        } catch (Exception e) {
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }
        return mIcon11;
    }

    protected void onPostExecute(Bitmap result) {
        bmImage.setImageBitmap(result);
    }

}

}