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ListView分页异步加载数据
package com.example.datapageload;
import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.widget.AbsListView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
/**
*
* <p>Title: 主界面 </p>
* <p>Description:
* listView的数据的分批加载
* Handler Thread实现异步加载数据
* 环形进度条 文字 提示数据正在加载
* </p>
* <p>Create Time: 2013-9-17 </p>
* <p>Update Time: </p>
* <p>Updater: </p>
* <p>Update Comments: </p>
*/
public class MainActivity extends Activity {
private ListView lv;
private ArrayAdapter<String> adapter;
private View footer;//页脚
private List<String> lstDatas = new ArrayList<String>();
private int number = 20;//每次加载多少条数据
private int maxpage = 5;//总共多少页
private boolean loadfinish = true;//数据是否加载完成
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化组件
initComponent();
//注册监听
registerListener();
}
private void initComponent(){
lv = (ListView) this.findViewById(R.id.listView);
footer = LayoutInflater.from(this).inflate(R.layout.footer, null);
lstDatas = Data.getData(0, 20);
adapter = new ArrayAdapter<String>(this, R.layout.listview_item, R.id.textView, lstDatas);
//在设置适配器之前添加listview的页脚
lv.addFooterView(footer);
lv.setAdapter(adapter);
//移除页脚
lv.removeFooterView(footer);
}
private void registerListener(){
//监听滚动事件
lv.setOnScrollListener(new OnScrollListener());
}
class OnScrollListener implements android.widget.AbsListView.OnScrollListener{
@Override
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;
//刚开始,firstVisibleItem、visibleItemCount、totalItemCount都为0,则lastItemId为-1
//分页 1.totalItemCount需要大于0 2.要计算出最后一项的索引 3.判断最后一页 是,不加载
if(totalItemCount > 0 ){
//最后一条记录的id
int lastItemId = lv.getLastVisiblePosition();
if((lastItemId 1) == totalItemCount){//最后一条记录的id加1等于记录总数 加载下一页
//计算当前页
int currentpage = totalItemCount/number == 0 ? totalItemCount/number : totalItemCount/number 1;
//下一页 当数据加载完成才可以加载下一页的数据
int nextpage = currentpage 1;
if(nextpage <= maxpage && loadfinish){
loadfinish = false;
//在加载数据之前显示页脚
lv.addFooterView(footer);
new Thread(
new Runnable() {
@Override
public void run() {
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
List<String> result = Data.getData(loadtotal, number);
handler.sendMessage(handler.obtainMessage(100,result));
}
}).start();
}
}
}
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
Log.i("MainActivity", "onScrollStateChanged(scrollState=" scrollState ")");
}
}
private Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case 100:
lstDatas.addAll((List<String>)msg.obj);
adapter.notifyDataSetChanged();//告诉listView数据已经改变,要求更新界面显示
if(lv.getFooterViewsCount() > 0 ){
//移除页脚
lv.removeFooterView(footer);
}
//加载完成
loadfinish = true;
break;
default:
break;
}
}
};
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}