android 批量加载数据

public class MainActivity extends Activity {
    private ListView listView;
    private List<String> data = new ArrayList<String>();
    ArrayAdapter<String> adapter;
    View footer;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        ///通过xml布局文件生成View对象
        footer = getLayoutInflater().inflate(R.layout.footer, null);

        listView = (ListView) this.findViewById(R.id.listView);

        //为ListView设置滑动监听事件处理器
        listView.setOnScrollListener(new ScrollListener());

        data.addAll(DataService.getData(0, 20));
        adapter = new ArrayAdapter<String>(this, R.layout.listview_item, R.id.textView, data);
        listView.addFooterView(footer);//添加页脚(放在ListView最后，并且要放在setAdapter()方法之前，因为内部会有所包装)
        listView.setAdapter(adapter);
        listView.removeFooterView(footer);//刚开始时删除页脚
    }

    private int number = 20;//每次获取多少条数据
    private int maxpage = 5;//总共有多少页
    private boolean loadfinish = true;
    private final class ScrollListener implements OnScrollListener{
        public void onScrollStateChanged(AbsListView view, int scrollState) {
            Log.i("MainActivity", "onScrollStateChanged(scrollState="+ scrollState+ ")");
        }

        public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
            Log.i("MainActivity", "onScroll(firstVisibleItem="+ firstVisibleItem+ ",visibleItemCount="+
                    visibleItemCount+ ",totalItemCount="+ totalItemCount+ ")");

            final int loadtotal = totalItemCount;
            int lastItemid = listView.getLastVisiblePosition();//获取当前屏幕最后Item的ID
            if((lastItemid+1) == totalItemCount){//达到数据的最后一条记录
                if(totalItemCount > 0){
                    //当前页
                    int currentpage = totalItemCount%number == 0 ? totalItemCount/number : totalItemCount/number+1;
                    int nextpage = currentpage + 1;//下一页
                    if(nextpage <= maxpage && loadfinish){
                        loadfinish = false;
                        //加载数据时显示页脚
                        listView.addFooterView(footer);

                        new Thread(new Runnable() {
                            public void run() {
                                try {
                                    Thread.sleep(3000);
                                } catch (InterruptedException e) {
                                    e.printStackTrace();
                                }
                                List<String> result = DataService.getData(loadtotal, number);
                                handler.sendMessage(handler.obtainMessage(100, result));
                            }
                        }).start();
                    }
                }

            }
        }
    }

    Handler handler = new Handler(){
        public void handleMessage(Message msg) {
            data.addAll((List<String>) msg.obj);
            adapter.notifyDataSetChanged();//告诉ListView数据已经发生改变，要求ListView更新界面显示
            if(listView.getFooterViewsCount() > 0) listView.removeFooterView(footer);
            loadfinish = true;
        }
    };

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >
    <!--系统中的圆形滚动条-->

    <ProgressBar android:id="@+id/c81_forthBar"
        android:layout_width="50dp"
        android:layout_height="wrap_content"
         style="?android:attr/progressBarStyle" />
    <TextView android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_vertical"
    android:textSize="20sp"
    android:text="数据正在加载..."
    />
</LinearLayout>
<!--页脚xml-->