android – 使用Cursor和ListView适配器获取大量数据

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我正在使用自定义CursorAdapter从sqlite数据库获取数据并在列表视图中显示它.该数据库包含2列,大约8.000行.所以我正在寻找一种方法查询和尽快显示所有数据.我用asyncTask完成了这个是代码
private class PrepareAdapter extends AsyncTask<Void,Void,CustomCursorAdapter > {

 @Override
 protected void onPreExecute() {
     dialog.setMessage("Wait");
     dialog.setIndeterminate(true);
     dialog.setCancelable(false);
     dialog.show();


     Log.e("TAG","Posle nov mAdapter");
 }

 @Override
 protected CustomCursorAdapter doInBackground(Void... unused) {

   Cursor cursor =  myDbNamesHelper.getCursorQueryWithAllTheData();
   mAdapter.changeCursor(cursor);
   startManagingCursor(cursor);
   Log.e("TIME","posle start managing Cursor" + String.valueOf(SystemClock.elapsedRealtime()-testTime)+ " ms");
     testTime=SystemClock.elapsedRealtime();

     mAdapter.initIndexer(cursor);
     return mAdapter;
 }

 protected void onPostExecute(CustomCursorAdapter result) {

     TabFirstView.this.getListView().setAdapter(result);
     Log.e("TIME","posle adapterSet" + String.valueOf(SystemClock.elapsedRealtime()-testTime)+ " ms");
    testTime=SystemClock.elapsedRealtime();
     dialog.dismiss();
 }

}

除了我需要将结果设置为适配器的部分之外,这个工作正常.我做了一些时间测试,需要大约700毫秒来使它超过startManagingCursor.问题是它需要大约7秒才能超过setAdapter(结果)并且这是在UI线程中运行所以它使我的应用程序无响应(进度对话框冻结,有时会应用程序).我如何减少这个时间?我可以使这也在后台运行或以任何方式提高响应能力?

TNX.

public class CustomCursorAdapter extends SimpleCursorAdapter implements OnClickListener,SectionIndexer,Filterable,android.widget.AdapterView.OnItemClickListener{

    private Context context;
    private int layout;
    private AlphabetIndexer alphaIndexer;

    public CustomCursorAdapter (Context context,int layout,Cursor c,String[] from,int[] to) {
        super(context,layout,c,from,to);
        this.context = context;
        this.layout = layout;

    }
    public void initIndexer(Cursor c){
         alphaIndexer=new AlphabetIndexer(c,c.getColumnIndex(DataBaseNamesHelper.COLUMN_NAME)," ABCDEFGHIJKLMNOPQRSTUVWXYZ");
    }

    @Override
    public View newView(Context context,Cursor cursor,ViewGroup parent) {

        Cursor c = getCursor();

        final LayoutInflater inflater = LayoutInflater.from(context);
        View v = inflater.inflate(layout,parent,false);

        int nameCol = c.getColumnIndex(DataBaseNamesHelper.COLUMN_NAME);

        String name = c.getString(nameCol);

        /**
         * Next set the name of the entry.
         */
        TextView name_text = (TextView) v.findViewById(R.id.name_entry);
        if (name_text != null) {
            name_text.setText(name);
        }

        int favCol = c.getColumnIndex(DataBaseNamesHelper.COLUMN_FAVOURITED);
        int fav = c.getInt(favCol);

        int idCol = c.getColumnIndex(DataBaseNamesHelper.COLUMN_ID);

        Button button = (Button) v.findViewById(R.id.Button01);
        button.setOnClickListener(this);
        button.setTag(c.getInt(idCol));
        if(fav==1){
            button.setVisibility(View.INVISIBLE);
        }
        else button.setVisibility(View.VISIBLE);

        return v;
    }

    @Override
    public void bindView(View v,Context context,Cursor c) {

        int nameCol = c.getColumnIndex(DataBaseNamesHelper.COLUMN_NAME);

        String name = c.getString(nameCol);

        /**
         * Next set the name of the entry.
         */
        TextView name_text = (TextView) v.findViewById(R.id.name_entry);
        if (name_text != null) {
            name_text.setText(name);
        }
        int favCol = c.getColumnIndex(DataBaseNamesHelper.COLUMN_FAVOURITED);
        int fav = c.getInt(favCol);

        Button button = (Button) v.findViewById(R.id.Button01);
        button.setOnClickListener(this);
        int idCol = c.getColumnIndex(DataBaseNamesHelper.COLUMN_ID);
        button.setTag(c.getInt(idCol));
      //  Log.e("fav",String.valueOf(fav));
        if(fav==1){
            button.setVisibility(View.INVISIBLE);
        } else button.setVisibility(View.VISIBLE);
    }



    @Override
    public int getPositionForSection(int section) {
        return alphaIndexer.getPositionForSection(section);
    }

    @Override
    public int getSectionForPosition(int position) {
          return alphaIndexer.getSectionForPosition(position);
    }

    @Override
    public Object[] getSections() {
          return alphaIndexer.getSections();
    }
    @Override
    public void onItemClick(AdapterView<?> arg0,View arg1,int arg2,long arg3) {
        Log.e("item Click",arg1.toString()+ " position> " +arg2);
    }

    @Override
    public void onClick(View v) {
            if(v.getId()==R.id.Button01){
                //Log.e("Button Click",v.toString()+ " position> " +v.getTag().toString());
                v.setVisibility(View.INVISIBLE);
                DataBaseNamesHelper dbNames = new DataBaseNamesHelper(context);
                dbNames.setFavouritesFlag(v.getTag().toString());
            }

        }



}

解决方法

加载适配器的时间较慢的原因是CursorAdapter对Cursor.getCount()的内部调用.

Android中的游标被懒散加载.在需要之前不会加载结果.当CursorAdapter调用getCount()时,这会强制查询完全执行并计算结果.

以下是一些讨论这个问题的链接.

http://groups.google.com/group/android-developers/browse_thread/thread/c1346ec6e2310c0c

http://www.androidsoftwaredeveloper.com/2010/02/25/sqlite-performance/

我的建议是拆分你的查询.仅加载屏幕上可见列表项的数量.当用户滚动加载下一组时.非常像GMail和市场应用程序.不幸的是我没有一个方便的例子:(

这不能回答你的问题,但希望它能提供一些见解:)

原文链接:https://www.f2er.com/android/317526.html

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