Android中ListView動態(tài)加載數(shù)據

1、Android中ListView動態(tài)加載數(shù)據2011-11-0519:021.引言：為了提高ListView的效率和應用程序的性能，在Android應用程序中不應該一次性加載ListView所要顯示的全部信息，而是采所需的數(shù)據，并渲染到Listview組件中，這樣可以極大的改善應用程序的性能和用戶體驗。2.交互：進入ListView組件，首先預加載N條記錄，當用戶滑動到最后一條記錄顯示加載提示信息，并從后臺加載N條數(shù)據，接著渲染3.效果圖：4.程序實現(xiàn)：packagecom.focus.loading;importandroid.app.ListActivity;importandroid.o

2、s.Bundle;importandroid.os.Handler;importandroid.view.Gravity;importandroid.view.View;importandroid.view.ViewGroup;importandroid.widget.AbsListView;importandroid.widget.BaseAdapter;importandroid.widget.LinearLayout;importandroid.widget.ListView;importandroid.widget.ProgressBar;importandroid.widget.Te

3、xtView;importandroid.widget.AbsListView.OnScrollListener;importandroid.widget.LinearLayout.LayoutParams;publicclassListViewLoadingActivityextendsListActivityimplementsOnScrollListenerOverridepublicvoidonCreate(BundlesavedInstanceState)super.onCreate(savedInstanceState);/*加載項布局，此布局被添加到ListView的Footer

4、中。*/mLoadLayout=newLinearLayout(this);mLoadLayout.setMinimumHeight(60);mLoadLayout.setGravity(Gravity.CENTER);mLoadLayout.setOrientation(LinearLayout.HORIZONTAL);/*向加載項布局中添加一個圓型進度條。*/ProgressBarmProgressBar=newProgressBar(this);mProgressBar.setPadding(0,0,15,0);mLoadLayout.addView(mProgressBar,mProg

5、ressBarLayoutParams);/*向加載項布局中添加提示信息。*/TextViewmTipContent=newTextView(this);mTipContent.setText(加載中);mLoadLayout.addView(mTipContent,mTipContentLayoutParams);/*獲取ListView組件，并將加載項布局添加到ListView組件的Footer中。*/mListView=getListView();mListView.addFooterView(mLoadLayout);/*組ListView組件設置Adapter,并設置滑動監(jiān)聽事件。*

6、/setListAdapter(mListViewAdapter);mListView.setOnScrollListener(this);publicvoidonScroll(AbsListViewview,intmFirstVisibleItem,intmVisibleItemCount,intmTotalItemCount)mLastItem=mFirstVisibleItem+mVisibleItemCount-1;if(mListViewAdapter.countmCount)mListView.removeFooterView(mLoadLayout);publicvoidonSc

7、rollStateChanged(AbsListViewview,intmScrollState)這時應該加載剩余數(shù)據/*當ListView滑動到最后一條記錄時這時，我們會看到已經被添加到ListView的加載項布局,*/if(mLastItem=mListViewAdapter.count&mScrollState=OnScrollListener.SCROLL_STATE_IDLE)if(mListViewAdapter.count=mCount)mHandler.postDelayed(newRunnable()Overridepublicvoidrun()mListViewAdapte

8、r.count+=10;mListViewAdapter.notifyDataSetChanged();mListView.setSelection(mLastItem);,1000);classListViewAdapterextendsBaseAdapterintcount=10;publicintgetCount()returncount;publicObjectgetItem(intposition)returnposition;publiclonggetItemId(intposition)returnposition;publicViewgetView(intposition,Vi

9、ewview,ViewGroupparent)TextViewmTextView;if(view=null)mTextView=newTextView(ListViewLoadingActivity.this);elsemTextView=(TextView)view;mTextView.setText(Item+position);mTextView.setTextSize(20f);mTextView.setGravity(Gravity.CENTER);mTextView.setHeight(60);returnmTextView;privateLinearLayoutmLoadLayo

10、ut;privateListViewmListView;privateListViewAdaptermListViewAdapter=newListViewAdapter();privateintmLastItem=0;privateintmCount=41;privatefinalHandlermHandler=newHandler();privatefinalLayoutParamsmProgressBarLayoutParams=newLinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,LinearLayout.LayoutParams.WRAP_CONT