android - 图像在滚动 ListView 上刷新

Question

我使用的 ListView 有 3 个字段，1 个 ImageView 和 2 个 TextView 。我正在解析 ListView 的 json 数据。当我滚动 ListView 时， ImageView 中的图像发生变化，然后当我滚动回顶部时，它再次发生变化。我正在显示来自 URL 的图像。

下面是部分代码:

public ArrayList<HashMap> dataToList(List<CatalogTopCategory> detailsList) {
    list = new ArrayList<HashMap>();

    for (CatalogTopCategory catalogTopCategory : detailsList) {
        HashMap temp = new HashMap();
        temp.put(FIRST_COLUMN, catalogTopCategory.getCategoryName());
        temp.put(SECOND_COLUMN, catalogTopCategory.getCategoryDesc());
        temp.put(THIRD_COLUMN, catalogTopCategory.getCategoryBannner());
        temp.put(FIFTH_COLUMN, catalogTopCategory.getCategoryThumbnail());
        temp.put(FORTH_COLUMN, catalogTopCategory.getCategoryId());
        list.add(temp);
    }
    return list;
}



final ArrayList<HashMap> hashMaps = dataToList(storeCatList);
        catalogTopAdapter = new CatalogTopAdapter(StoreLanding.this,
                hashMaps, getApplicationContext());
        listView.setAdapter(catalogTopAdapter);

适配器类代码如下:

 public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder holder;
            LayoutInflater inflater =  activity.getLayoutInflater();
            if (convertView == null)
            {
                convertView = inflater.inflate(R.layout.catalog_listview, null);
                holder = new ViewHolder();
                holder.imageView = (ImageView)convertView.findViewById(R.id.imageView2);
                holder.txtFirst = (TextView) convertView.findViewById(R.id.FirstText);
                holder.txtSecond = (TextView) convertView.findViewById(R.id.SecondText);
                convertView.setTag(holder);
            }
            else
            {
                holder = (ViewHolder) convertView.getTag();
            }
            Typeface type = Typeface.createFromAsset(mContext.getAssets(),"fonts/FeedSpeedFonts.otf"); 
            holder.txtFirst.setTypeface(type);
            holder.txtSecond.setTypeface(type);
            HashMap map = list.get(position);
            new LoadImage(holder.imageView).execute(String.valueOf(map.get(FIFTH_COLUMN)));
            holder.txtFirst.setText((CharSequence) map.get(FIRST_COLUMN));
            holder.txtSecond.setText((CharSequence) map.get(SECOND_COLUMN));                
            convertView.setTag(holder);
        return convertView;
}

加载图片:

private class LoadImage extends AsyncTask<String, Void, Bitmap> {
    ImageView bmImage;
    public LoadImage(ImageView bmImage) {
        this.bmImage = bmImage;
    }

    protected Bitmap doInBackground(String... urls) {
        String urldisplay = urls[0];
        Bitmap mIcon = null;
        try {
            mIcon = BitmapFactory.decodeResource(mContext.getResources(), R.drawable.default_image);
            InputStream in = new java.net.URL(urldisplay).openStream();
            mIcon = BitmapFactory.decodeStream(in);
        } catch (Exception e) {
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }
        return mIcon;
    }
    protected void onPostExecute(Bitmap result) {
        bmImage.setImageBitmap(Bitmap.createScaledBitmap(result, 100, 100,
                false));
    }
}

Answer 1

此 new LoadImage(holder.imageView).execute(String.valueOf(map.get(FIFTH_COLUMN))); 导致刷新图像时出现问题。刷新 View 时，您每次都会启动 asynctask。当您的 View 将被重用时，您的异步任务会在位置上显示不良图像，因此您的异步任务会再次启动并显示良好的图像。您不能以这种方式设置图像。 Android 社​​区使用

• 毕加索
• 通用图像加载器
• Volley 图像加载器
• 滑行