private ListView lv;
// 适配器数据集合
private List<String> list = new ArrayList<String>();
// 适配器
private ArrayAdapter<String> adapter;
// 判断是否到达低端
private boolean isBottom;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv = (ListView) findViewById(R.id.lv);
initData();
// 创建适配器对象
adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, list);
// 设置适配器
lv.setAdapter(adapter);
lv.setOnScrollListener(new OnScrollListener() {
// view：ListView
// scrollState有3种状态：停止SCROLL_STATE_IDLE
// 触摸滚动:SCROLL_STATE_TOUCH_SCROLL 快速滑动:SCROLL_STATE_FLING
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
// TODO Auto-generated method stub
switch (scrollState) {
// 快速滑动
case SCROLL_STATE_FLING:
Log.i("onScrollStateChanged", "快速滑动");
break;
// 停止
case SCROLL_STATE_IDLE:
Log.i("onScrollStateChanged", "没有滑动");
if (isBottom) {
// 加载下页数据
MyAsyncTask task = new MyAsyncTask();
task.execute();
// 改变
isBottom = false;
}
break;
// 触摸滚动
case SCROLL_STATE_TOUCH_SCROLL:
Log.i("onScrollStateChanged", "触摸滑动");
break;
}
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
// TODO Auto-generated method stub
Log.i("onScroll", "firstVisibleItem----->" + firstVisibleItem);
Log.i("onScroll", "visibleItemCount----->" + visibleItemCount);
Log.i("onScroll", "totalItemCount----->" + totalItemCount);
// 判断如果第一个可见的Item项的索引值+页面的Item的数量==本次加载的Item的总数量 ---》 则到达低端
if (firstVisibleItem + visibleItemCount == totalItemCount) {
isBottom = true;
}
}
});
}
// 初始化数据
private void initData() {
for (int i = 0; i < 20; i++) {
list.add("白菜价U盘" + i);
}
}
// 开启异步任务加载新的数据
public class MyAsyncTask extends AsyncTask<Void, Void, List<String>> {
private ProgressDialog dialog;
// 初始化进度框
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
dialog = new ProgressDialog(MainActivity.this);
dialog.setMessage("请稍后...");
dialog.show();
}
// 模拟后台加载数据
@Override
protected List<String> doInBackground(Void... params) {
List<String> list = new ArrayList<String>();
for (int i = 0; i < 20; i++) {
list.add("大白菜甩卖" + i);
try {
Thread.sleep(500);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
// 返回新加载的数据
return list;
}
// 拿到数据更新适配器
@Override
protected void onPostExecute(List<String> result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
// 对话框消失
dialog.dismiss();
// 判断
if (result != null) {
// 将数据添加到适配器的集合中
list.addAll(result);
}
adapter.notifyDataSetChanged();
}
}