listview滚动到底部自动加载数据

在android中listvieww加载数据,有的是分批加载,比如每次加载20条,100条就要加载5次,如果一次性加载100条,listview加载就变的慢,如果是有图片的话,一时浪费流量,二是item中带图片会出现错位的问题,listview加载数据目前好多app做法

一：分批加载 滑动到底部自动更新

二：滑动到底部 手动的点击加载更多

三：下拉刷新+底部加载更多

今天就讲下listview滑动到底部自动更新

分析：监听listview的滑动事件,判断listview是否滑动到底部,然后去加载数据

代码如下：

public class MainActivity extends Activity {
private ListView listview;
private List<String> datas;
private LayoutInflater inflater;
private MyAdapter adapter;
private List<String>  contents;
private int count = 0;
private View footView;
private Handler handler = new Handler();
int lastItem;
private RelativeLayout loading;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initData();
inflater = LayoutInflater.from(this);
listview = (ListView) findViewById(R.id.listview);
adapter = new MyAdapter();
footView = inflater.inflate(R.layout.footer, null);
loading = (RelativeLayout) footView.findViewById(R.id.loading);
//listview的addFooterView()添加view到listview底部一定要加在listview.setAdapter(adapter);这代码前面
listview.addFooterView(footView);
listview.setAdapter(adapter);
//添加listview滚动监听
listview.setOnScrollListener(new OnScrollListener() {
//AbsListView view 这个view对象就是listview
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
if (scrollState == OnScrollListener.SCROLL_STATE_IDLE) {
if (view.getLastVisiblePosition() == view.getCount() - 1) {
loadData();
}
}
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
lastItem = firstVisibleItem + visibleItemCount - 1 ;
}
});
}
protected void loadData() {
loading.setVisibility(View.VISIBLE);
handler.postDelayed(new Runnable() {
@Override
public void run() {
load();
loading.setVisibility(View.GONE);
adapter.notifyDataSetChanged();
}
}, 5000);
}
protected void load() {
int count=adapter.getCount()+1;
for(int i=count;i<count+20;i++){
contents.add("加载数据:::"+i);
}
}
private void initData() {
contents = new ArrayList<String>();
for(int i=1;i<20;i++){
contents.add("加载数据:::"+i);
}
}

class MyAdapter extends BaseAdapter{
@Override
public int getCount() {
return contents.size();
}
@Override
public Object getItem(int position) {
return contents.get(position);
}

@Override
public long getItemId(int position) {
return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if(convertView==null){
convertView = inflater.inflate(R.layout.item, parent, false);
holder = new ViewHolder();
holder.tvContent = (TextView) convertView.findViewById(R.id.tvContent);
convertView.setTag(holder);
}else{
holder = (ViewHolder) convertView.getTag();
}
holder.tvContent.setText(contents.get(position));
return convertView;
}
class ViewHolder{
TextView tvContent;
}
}
}