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);