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我正在列出設備內存中的視頻，其中BaseAdapter我注意到滾動效果不是很好，很慢。 我應該使用不同的方法來完成這項工作，還是有一種方法可以改進這項工作？Android BaseAdapter滾動緩慢
public class StoredVideo extends Activity {
public final static String EXTRA_MESSAGE = "it.mypackage.com";
private Cursor videocursor;
private int video_column_index;
ListView videolist;
int count;
String[] thumbColumns = { MediaStore.Video.Thumbnails.DATA,
MediaStore.Video.Thumbnails.VIDEO_ID };
private String thumbPath;
SharedPreferences pref;
String account;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.videomain);
pref = getSharedPreferences("AppPref", MODE_PRIVATE);
init_phone_video_grid();
}
@SuppressWarnings("deprecation")
private void init_phone_video_grid() {
System.gc();
String[] proj = { MediaStore.Video.Media._ID,
MediaStore.Video.Media.DATA,
MediaStore.Video.Media.DISPLAY_NAME,
MediaStore.Video.Media.SIZE };
String orderBy = android.provider.MediaStore.Video.Media.DATE_TAKEN;
videocursor = managedQuery(MediaStore.Video.Media.EXTERNAL_CONTENT_URI,
proj, null, null, orderBy + " DESC");
count = videocursor.getCount();
videolist = (ListView) findViewById(R.id.PhoneVideoList);
videolist.setAdapter(new VideoAdapter(getApplicationContext()));
videolist.setOnItemClickListener(videogridlistener);
videolist.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> av, View v, int pos, long id) {
return onLongListItemClick(v, pos, id);
}
protected boolean onLongListItemClick(View v, final int pos, long id) {
final String str= videolist.getItemAtPosition(pos).toString();
Log.i("ListView", "onLongListItemClick stirng=" + str);
AlertDialog.Builder builder = new
AlertDialog.Builder(StoredVideo.this);
builder.setMessage("Are you sure you want to delete this video ?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
if(videocursor.moveToFirst()) {
videocursor.moveToPosition(pos);
video_column_index = videocursor
.getColumnIndexOrThrow(MediaStore.Video.Media.DATA);
String filename = videocursor.getString(video_column_index);
removeMedia(filename);
videocursor.close();
sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://" + Environment.getExternalStorageDirectory())));
init_phone_video_grid();
}
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
AlertDialog alert = builder.create();
alert.show();
return true;
}
});
}
private OnItemClickListener videogridlistener = new OnItemClickListener() {
public void onItemClick(AdapterView parent, View v, int position,
long id) {
System.gc();
video_column_index = videocursor
.getColumnIndexOrThrow(MediaStore.Video.Media.DATA);
videocursor.moveToPosition(position);
String filename = videocursor.getString(video_column_index);
Log.d("TAGME", filename);
String videoinfo[] = new String[2];
int videoId = videocursor.getInt(videocursor.getColumnIndexOrThrow(MediaStore.Video.Media._ID));
Cursor videoThumbnailCursor = managedQuery(MediaStore.Video.Thumbnails.EXTERNAL_CONTENT_URI,
thumbColumns, MediaStore.Video.Thumbnails.VIDEO_ID+ "=" + videoId, null, null);
if (videoThumbnailCursor.moveToFirst()) {
thumbPath = videoThumbnailCursor.getString(videoThumbnailCursor.getColumnIndex(MediaStore.Video.Thumbnails.DATA));
Log.d("ThumbPath: ",thumbPath);
}
videoinfo[0] = filename;
videoinfo[1] = thumbPath;
Intent intent = new Intent(StoredVideo.this, ViewVideo.class);
intent.putExtra(EXTRA_MESSAGE, videoinfo);
StoredVideo.this.startActivity(intent);
}
};
public void removeMedia(String filename) {
File existingFile = new File("\"" + filename + "\"");
existingFile.delete();
Toast.makeText(StoredVideo.this, "File " + filename + " deleted", Toast.LENGTH_LONG).show();
ContentResolver resolver = StoredVideo.this.getContentResolver();
resolver.delete(Video.Media.EXTERNAL_CONTENT_URI, Video.Media.DATA + "=?", new String[]{filename});
}
public class VideoAdapter extends BaseAdapter {
private Context vContext;
public VideoAdapter(Context c) {
vContext = c;
}
public int getCount() {
return count;
}
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
public void deleteItem(int position) {
}
public View getView(int position, View convertView, ViewGroup parent) {
System.gc();
ViewHolder holder;
String id = null;
convertView = null;
if (convertView == null) {
convertView = LayoutInflater.from(vContext).inflate(
R.layout.listitem, parent, false);
holder = new ViewHolder();
holder.txtTitle = (TextView) convertView
.findViewById(R.id.txtTitle);
holder.thumbImage = (ImageView) convertView
.findViewById(R.id.imgIcon);
video_column_index = videocursor
.getColumnIndexOrThrow(MediaStore.Video.Media.DISPLAY_NAME);
videocursor.moveToPosition(position);
id = videocursor.getString(video_column_index);
video_column_index = videocursor
.getColumnIndexOrThrow(MediaStore.Video.Media.SIZE);
videocursor.moveToPosition(position);
holder.txtTitle.setText(id);
String[] proj = { MediaStore.Video.Media._ID,
MediaStore.Video.Media.DISPLAY_NAME,
MediaStore.Video.Media.DATA };
@SuppressWarnings("deprecation")
Cursor cursor = managedQuery(
MediaStore.Video.Media.EXTERNAL_CONTENT_URI, proj,
MediaStore.Video.Media.DISPLAY_NAME + "=?",
new String[] { id }, null);
if(cursor.moveToFirst()) {
long ids = cursor.getLong(cursor
.getColumnIndex(MediaStore.Video.Media._ID));
ContentResolver crThumb = getContentResolver();
BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 1;
Bitmap curThumb = MediaStore.Video.Thumbnails.getThumbnail(
crThumb, ids, MediaStore.Video.Thumbnails.MICRO_KIND,
options);
holder.thumbImage.setImageBitmap(curThumb);
curThumb = null;
}
}
return convertView;
}
}
static class ViewHolder {
TextView txtTitle;
TextView txtSize;
ImageView thumbImage;
}
}
首先，當您僅使用遊標獲取單個值時，請勿使用managedQuery。然後，在不需要時關閉光標。那麼，使用查詢來獲取每個ID的事實肯定會很慢，因爲您匹配每個視頻的視頻名稱。最後，得到縮略圖也很慢，你應該考慮在asynctask中這樣做。 – njzk2
你不需要一個新的查詢來獲得id，它已經在你的'videocursor'中。 – njzk2
另外，由於您在適配器中使用了光標，因此您可以使用cursoradapter，它可以爲您完成一些工作。 – njzk2