ListView分页异步加载数据

【实例简介】ListView分页异步加载数据
【实例截图】

【核心代码】

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;
 }

}