android – Lazy加载到ListView with Image. (光标适配器)

我有一个列表视图显示视频与他们的缩略图,我正在使用光标适配器(使用ContentProvider的获取).问题是列表项增加列表视图的性能变得非常差.请让我知道最好的方法,使其懒惰加载.

新的：
最后我得到了一些解决方案.它的工作对我很好.如有任何建议,请通知我.
我的新代码在这里. (它使用堆栈与生产者消费者patern和bacground线程进行)

@覆盖
public void bindView(View view,Context context,Cursor cursor){

ViewHolder holder = (ViewHolder) view.getTag();
    String name = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Video.Media.TITLE));
    int id = cursor.getInt(cursor.getColumnIndexOrThrow(MediaStore.Video.Media._ID));
    holder.getIdView().setText(name);
    holder.getThumbView().setTag((Integer)id);
    if(LazyLoader.getInstance().containsKey(id)) {
        Object bitmap = LazyLoader.getInstance().getBitMap(id);
        if(null != bitmap && (bitmap instanceof  Bitmap)) {
            holder.getThumbView().setimageBitmap((Bitmap)bitmap);
        } else {
            holder.getThumbView().setimageDrawable(null);
        }
    } else {
        holder.getThumbView().setimageDrawable(null);
        LazyItem lazyItem = new LazyItem();
        lazyItem.setId(id);
        lazyItem.setThumbNail(holder.getThumbView());
        LazyLoader.getInstance().putItem(lazyItem);
    }
}




public class LazyLoaderHelper extends Thread {

    private ContentResolver resolver = null;
    private Activity activity;
    private boolean isActive = true;
    ExecutorService executor;


    public LazyLoaderHelper(Activity _activity,ContentResolver _resolver) {
        resolver = _resolver;
        activity = _activity;
        isActive = true;
        executor = Executors.newFixedThreadPool(10);
    }

    public void stopThread() {
        isActive = false;
        executor.shutdown();
    }

    @Override
    public void run() {
        while (isActive) {
            if(LazyLoader.getInstance().getSize() > 0) {
                final  LazyItem lazyItem = LazyLoader.getInstance().getItem();
                if(null != lazyItem) {

                    executor.execute(new Runnable() {
                        @Override
                        public void run() {

                            BitmapFactory.Options options = new BitmapFactory.Options();
                            options.inSampleSize = 1;

                            if ((null != resolver) && (null != activity)) {
                                final Bitmap thumb = MediaStore.Video.Thumbnails.getThumbnail(resolver,lazyItem.getId(),MediaStore.Video.Thumbnails.MICRO_KIND,options);
                                if (null != thumb) {
                                    LazyLoader.getInstance().putBitMap(lazyItem.getId(),thumb);
                                } else {
                                    LazyLoader.getInstance().putBitMap(lazyItem.getId(),new Object());
                                }

                                if ((Integer) lazyItem.getThumbNail().getTag() == lazyItem.getId()) {
                                    activity.runOnUiThread(new Runnable() {
                                        @Override
                                        public void run() {
                                            if (null != thumb) {
                                                lazyItem.getThumbNail().setimageBitmap(thumb);
                                            } else {
                                                lazyItem.getThumbNail().setimageDrawable(null);
                                            }
                                        }
                                    });
                                }
                            }
                        }
                    });
                }
            }

        }
    }
}

解决方法

您可以使用picaso库的Android它是开源的,可以轻松地与您的应用程序集成,您可以从github从下面的链接下载库

http://square.github.io/picasso/

并且可以通过在列表视图适配器中使用以下方法轻松实现延迟加载

毕加索支持下载和错误占位符作为可选功能.

Picasso.with(上下文)
.load(URL)
.placeholder(R.drawable.user_placeholder)
.error(R.drawable.user_placeholder_error)
.into(ImageView的);

所有资源,资产,文件,内容提供商都被作为图像来源.

Picasso.with(上下文).load(R.drawable.landing_screen).into(imageView1);Picasso.with(上下文).load( “文件：///android_asset/DvpvklR.png”).into(imageView2);Picasso.with(context).load(new File(…)).into(imageView3);