Question

我有GridView，其中包含Adapter，其中ArrayAdapter<Album>扩展Album（其中相册是从LastFM API获取的相册信息）。

Adapter信息附带图片的网址。我异步下载这些图像并将它们与专辑名称一起放在GridView中。

然而，当我向下和向上滚动HashMap<String, Bitmap>时，行会被回收。当我再次给它们充气时，图像会被交换，我真的不知道发生了什么。

我尝试将图像存储在Adapter中无济于事。

以下是我package com.gigtracker.adapter; import java.text.DecimalFormat; import java.util.Collection; import java.util.HashMap; import java.util.concurrent.CopyOnWriteArrayList; import android.annotation.SuppressLint; import android.app.Activity; import android.content.Context; import android.graphics.Bitmap; import android.os.AsyncTask; import android.util.TypedValue; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ArrayAdapter; import android.widget.ImageView; import android.widget.TextView; import com.garli.lastfmapi.Album; import com.garli.lastfmapi.Artist; import com.garli.lastfmapi.ImageSize; import com.gigtracker.R; import com.gigtracker.utils.ImageDownloader; public class AlbumAdapter extends ArrayAdapter<Album> { private final ImageDownloader d; int playcount; @SuppressLint("UseSparseArrays") private final HashMap<Integer, View> map = new HashMap<Integer, View>(); public AlbumAdapter(final Context ctx, final Artist artist) { super(ctx, 0); d = new ImageDownloader(); new AsyncTask<Void, Void, Void>() { CopyOnWriteArrayList<Album> albums = new CopyOnWriteArrayList<Album>(); @Override protected Void doInBackground(final Void... params) { final Collection<Album> albumCollection = Artist .getTopAlbums(artist.getName()); for (final Album album : albumCollection) { if (playcount < album.getPlaycount()) { playcount = album.getPlaycount(); } albums.add(album); } return null; } @Override protected void onPostExecute(final Void result) { for (final Album album : albums) { add(album); } notifyDataSetChanged(); } }.execute(); } @Override public View getView(final int position, View convertView, final ViewGroup parent) { final TextView tv, tv2; final ImageView iv; final Album album = getItem(position); if (map.get(Integer.valueOf(position)) == null) { if (convertView == null) { convertView = LayoutInflater.from(getContext()).inflate( R.layout.grid_item, null); tv = (TextView) convertView.findViewById(R.id.textViewName); iv = (ImageView) convertView.findViewById(R.id.imageView1); tv2 = (TextView) convertView.findViewById(R.id.textViewRating); @SuppressWarnings("deprecation") int buttonDimension = ((Activity) getContext()) .getWindowManager().getDefaultDisplay().getWidth() / 2; final int paddingTotal = (int) TypedValue.applyDimension( TypedValue.COMPLEX_UNIT_DIP, 20, getContext() .getResources().getDisplayMetrics()); buttonDimension -= paddingTotal; iv.getLayoutParams().height = buttonDimension; iv.getLayoutParams().width = buttonDimension; new AsyncTask<Void, Void, Void>() { Bitmap bmp; @Override protected Void doInBackground(final Void... params) { bmp = d.downloadBitmap(album .getImageURL(ImageSize.LARGE)); return null; } @Override protected void onPostExecute(final Void result) { iv.setImageBitmap(bmp); } }.execute(); } else { tv = (TextView) convertView.findViewById(R.id.textViewName); tv2 = (TextView) convertView.findViewById(R.id.textViewRating); } } else { convertView = map.get(Integer.valueOf(position)); tv = (TextView) convertView.findViewById(R.id.textViewName); tv2 = (TextView) convertView.findViewById(R.id.textViewRating); } tv.setText(album.getName()); final float percentage = 100 * (float) album.getPlaycount() / playcount; tv2.setText(new DecimalFormat("##0.00").format(percentage) + "%"); if (percentage >= 90) { tv2.setTextColor(0xff99ff33); } else if (percentage >= 75) { tv2.setTextColor(0xffffff66); } else if (percentage >= 50) { tv2.setTextColor(0xffff9900); } else if (percentage >= 25) { tv2.setTextColor(0xffcc6600); } else { tv2.setTextColor(0xffcc0000); } return convertView; } }

的代码

{{1}}

Answer 1

您应该使用模式ViewHolder：

public class NewHolder {
    public ImageView ivIcon;
    public TextView tvTitle;
    public int position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    NewHolder holder = null;

    UBRNew item = data.get(position);

    if (convertView == null) {
        holder = new NewHolder();
        convertView = inflater.inflate(R.layout.item_new, null);
        holder.tvTitle = (TextView) convertView.findViewById(R.id.tvTitle);
        holder.ivIcon = (ImageView) convertView.findViewById(R.id.ivIcon);
        convertView.setTag(holder);
    } else {
        holder = (NewHolder) convertView.getTag();
    }

holder.position = position;

holder.tvTitle.setText(Tools.replaceCharactersInEllipsis(item.getTitle()));
holder.ivIcon.setImageBitmap(((item.getIcon() == null) ? defaultIconForNew : item.getIcon()));

if ((!isFling) && (!item.isDownloadedIcon())) {
    new LazyLoadImage(context, 
                      this, 
                      item, 
                      holder, 
                      position, 
                      64,
                      64).execute();
}

    return convertView;
}

3

公共类LazyLoadImage扩展了AsyncTask {

private final String TAG = "LazyLoadThumbnail";

private NewHolder holder = null;
private UBRNew ubrNew = null;
private int position = 0;
private AdapterUbrNews adapter = null;
private int widthIcon = 0;
private int heightIcon = 0;
private DBNews db = null;
private Context context = null;

public LazyLoadImage(Context context,
                     AdapterUbrNews adapter, 
                     UBRNew ubrNew, 
                     NewHolder holder, 
                     int position, 
                     int widthIcon, 
                     int heightIcon) {
    this.adapter = adapter;
    this.holder = holder;
    this.position = position;
    this.ubrNew = ubrNew;
    this.widthIcon = widthIcon;
    this.heightIcon = heightIcon;

    this.ubrNew.setDownloadedIcon(true);

    db = DBNews.getInstance(context);

    this.context = context;
}

@Override
protected Bitmap doInBackground(Void... voids) {
    Bitmap result = null;

    try {
        Bitmap temp = download(ubrNew.getUrlIcon()); 

        if (temp != null) {
            result = Bitmap.createScaledBitmap(temp, widthIcon, heightIcon, true);
        }
    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

     return result;
}

@Override
protected void onPostExecute(Bitmap bitmap) {
    if (bitmap != null) {
        ubrNew.setIcon(bitmap);

        if (position == holder.position) {
            holder.ivIcon.setImageBitmap(bitmap);
        } else {
            adapter.notifyDataSetChanged();
        }
    } else {
        ubrNew.setDownloadedIcon(false);
    }
}

private Bitmap download(String urlString) throws MalformedURLException, IOException {
    if ((urlString == null) || (urlString.equals(""))) {
        return null;
    }

    DefaultHttpClient client = new DefaultHttpClient();
    HttpGet getRequest = new HttpGet(urlString);

    try {
        HttpResponse response = client.execute(getRequest);
        final int statusCode = response.getStatusLine().getStatusCode();
        if (statusCode != HttpStatus.SC_OK) {  
            return null;
        }

        final HttpEntity entity = response.getEntity();
        if (entity != null) {
            InputStream inputStream = null;
            try {
                inputStream = entity.getContent(); 
                return BitmapFactory.decodeStream(inputStream);
            } finally {
                if (inputStream != null) {
                    inputStream.close();  
                }
            }
        }
    } catch (Exception e) {}

    return null;
}

}

代码段中的LazyLoadImage中的所有功能：

if (position == holder.position) {
            holder.ivIcon.setImageBitmap(bitmap);
        } else {
            adapter.notifyDataSetChanged();
        }

ImageView被GridView回收

1 个答案: