0

嗨，我的应用程序是关于解析 xml 文件，然后从 url 加载图像以及文本并将其显示在列表视图中，但是每当我从 url 加载图像并且在向下滚动列表视图时它无法加载图像正确并强制关闭应用程序。现在如何克服这种情况。请帮助这里是我从 url 和文本下载图像的代码。

public class NewsRowAdapter extends ArrayAdapter<Item> 
{
    LoadingImage loadingImage;
    Bitmap bitmap = null;
    private Activity activity;
    private List<Item> items;
    private Item objBean;
    private int row;
    /*private DisplayImageOptions options;
    ImageLoader imageLoader;*/

    public NewsRowAdapter(Activity act, int resource, List<Item> arrayList) 
    {
        super(act, resource, arrayList);
        this.activity = act;
        this.row = resource;
        this.items = arrayList;

        /*options = new DisplayImageOptions.Builder().showStubImage(R.drawable.blank).showImageForEmptyUrl(R.drawable.blank).cacheInMemory().cacheOnDisc().build();
        imageLoader = ImageLoader.getInstance();*/


    }

    @Override
    public View getView(final int position, View convertView, ViewGroup parent)
    {
        View view = convertView;
        ViewHolder holder;
        if (view == null) 
        {
            LayoutInflater inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = inflater.inflate(row, null);

            holder = new ViewHolder();
            view.setTag(holder);
        } else 
        {
            holder = (ViewHolder) view.getTag();
        }

        if ((items == null) || ((position + 1) > items.size()))
            return view;

        objBean = items.get(position);

        holder.tvTitle = (TextView) view.findViewById(R.id.tvtitle);
        holder.tvDesc = (TextView) view.findViewById(R.id.tvdesc);
        holder.tvDate = (TextView) view.findViewById(R.id.tvdate);
        holder.imgView = (ImageView) view.findViewById(R.id.image);
        holder.pbar = (ProgressBar) view.findViewById(R.id.pbar);

        if (holder.tvTitle != null && null != objBean.getTitle() && objBean.getTitle().trim().length() > 0) 
        {
            holder.tvTitle.setText(Html.fromHtml(objBean.getTitle()));
        }
        if (holder.tvDesc != null && null != objBean.getDesc()
                && objBean.getDesc().trim().length() > 0) {
            holder.tvDesc.setText(Html.fromHtml(objBean.getDesc()));
        }
        if (holder.tvDate != null && null != objBean.getPubdate() && objBean.getPubdate().trim().length() > 0)
        {
            holder.tvDate.setText(Html.fromHtml(objBean.getPubdate()));
        }
        if (holder.imgView != null) 
        {
            if (null != objBean.getLink() && objBean.getLink().trim().length() > 0) 
            {
                final ProgressBar pbar = holder.pbar;
                pbar.setVisibility(View.INVISIBLE);
                //---------CHANGES MADE FOR LOADING IMAGE----------//
                Log.d("IMAGE NULL----------", objBean.getLink());


                try 
                {

                    URL linkurl = new URL(objBean.getLink());

                    bitmap = BitmapFactory.decodeStream(linkurl.openConnection().getInputStream());

                    holder.imgView.setImageBitmap(bitmap);

                } catch (MalformedURLException e) 
                {
                    e.printStackTrace();

                } catch (IOException e) 
                {
                    e.printStackTrace();
                }


                /*try 
                {
                    loadBitmap(objBean.getLink());

                } catch (IOException e) 
                {
                    e.printStackTrace();
                }
                */

                /*imageLoader.init(ImageLoaderConfiguration.createDefault(activity));
                imageLoader.displayImage(objBean.getLink(), holder.imgView, options, new ImageLoadingListener()
                {
                            @Override
                            public void onLoadingComplete() 
                            {
                                pbar.setVisibility(View.INVISIBLE);

                            }

                            @Override
                            public void onLoadingFailed() 
                            {
                                pbar.setVisibility(View.INVISIBLE);
                            }

                            @Override
                            public void onLoadingStarted()
                            {
                                pbar.setVisibility(View.VISIBLE);

                            }
                });*/

            } else 
            {
                holder.imgView.setImageResource(R.drawable.ic_launcher);
            }
        }

        return view;
    }





    public class ViewHolder
    {

        public TextView tvTitle, tvDesc, tvDate;
        private ImageView imgView;
        private ProgressBar pbar;

    }

}
4

2 回答 2

1

使用 AsyncTask 下载图像。检查这个：http ://android-developers.blogspot.in/2010/07/multithreading-for-performance.html

于 2013-02-07T10:31:25.990 回答
0

您正在 UI 线程上运行网络操作，尝试创建一个 AsyncTask 对作业执行，或者一个线程。这很容易，您所要做的就是将代码移过来。

由于您在适配器上使用 this，这意味着您将填充项目列表，您可能需要查看this。因为您想避免 listviews getView 问题的常规问题。

还有一些开源库可以帮助将 url 加载到图像中。例如，来自 Koush 的 UrlImageViewHelper可以帮助您很好地做到这一点。从您的适配器只需调用：

        if (holder.imgView != null) {
        if (null != objBean.getLink() && objBean.getLink().trim().length() > 0) {
            final ProgressBar pbar = holder.pbar;
            pbar.setVisibility(View.INVISIBLE);
            //---------CHANGES MADE FOR LOADING IMAGE----------//
            Log.d("IMAGE NULL----------", objBean.getLink());

            String linkurl = new URL(objBean.getLink().toString());
            UrlImageViewHelper.setUrlDrawable(holder.imgView, linkurl, R.id.your_default_drawable);

        }
于 2013-02-07T10:31:55.843 回答