安卓利用LoaderManager 检测数据源变化

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 安卓利用LoaderManager 检测数据源变化

LoaderManager:用来管理Loader,而Loader就是对应的数据源的加载器，当数据源发生变化，会触发onLoadFinished

  activity.getSupportLoaderManager().initLoader(0, null, new LoaderManager.LoaderCallbacks<Cursor>() {@Override
        public Loader<Cursor> onCreateLoader(int loaderID, Bundle args) {switch (loaderID){case 0:CursorLoader cursorLoader = new CursorLoader(activity,                                       
                            DBChatSessionView.CONTENT_URI,                      
                            new String[]{"sum(" + ccc+ ")"},                                              
                            null,                                                
                            null,                                                  
                            null                                             
                    );cursorLoader.setUpdateThrottle(100);return cursorLoader;default:break;}return null;}@Override
        public void onLoadFinished(Loader<Cursor> loader, Cursor returnCursor) {if(loader.getId() == 0){if (returnCursor != null && returnCursor.getCount() > 0){returnCursor.moveToPosition(-1);while (returnCursor.moveToNext()){int count = returnCursor.getInt(0);if(onChatUnreadCountListener != null){onsasCountListener.ondsdeadCount(count);}}}}}@Override
        public void onLoaderReset(Loader<Cursor> loader) {}});
} catch (Exception e) {
}