android cursorloader用法小姐,CursorLoader用法

CursorLoader继承与AsycTaskLoader，内部自带ContentObserver。我们可以用它来读取数据库，并自动检测数据源的更新。

下面是读取短信的例子

public class LoadersActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks {

private ListView mListView;

private MyAdapter mAdapter;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_loaders);

mListView = (ListView) findViewById(R.id.lv);

LoaderManager loaderManager = getSupportLoaderManager();

loaderManager.initLoader(0, null, this);

}

@Override

public Loader onCreateLoader(int id, Bundle args) {

Uri CONTACT_URI = Uri.parse("content://sms/");

CursorLoader cursorLoader = new CursorLoader(this, CONTACT_URI, null,

null, null, null);

return cursorLoader;

}

@Override

public void onLoadFinished(Loader loader, Cursor data) {

data.moveToFirst();

mAdapter = new MyAdapter(this, data);

mListView.setAdapter(mAdapter);

}

@Override

public void onLoaderReset(Loader loader) {

}

}

class MyAdapter extends BaseAdapter {

private List mDataList;

private Context context;

private Cursor cursor;

private class ViewHolder {

TextView textView;

}

public MyAdapter(Context context, Cursor cursor) {

this.context = context;

this.cursor = cursor;

}

public void setDataList(List dataList) {

this.mDataList = dataList;

}

@Override

public int getCount() {

return cursor.getCount();

}

@Override

public Object getItem(int position) {

return null;

}

@Override

public long getItemId(int position) {

return position;

}

@Override

public View getView(int position, View convertView, ViewGroup parent) {

ViewHolder viewHolder;

View view = convertView;

if (view == null) {

view = LayoutInflater.from(context).inflate(R.layout.item_cursor_loader, null);

viewHolder = new ViewHolder();

viewHolder.textView = (TextView) view.findViewById(R.id.textview);

view.setTag(viewHolder);

} else {

viewHolder = (ViewHolder) view.getTag();

}

cursor.moveToPosition(position);

viewHolder.textView.setText(cursor.getString(2));

return view;

}

}