Android开发中利用ListView怎么实现一个分页加载功能

package eoe.listview;import android.app.Activity;import android.database.Cursor;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.View;import android.widget.AdapterView;import android.widget.ListView;import android.widget.ProgressBar;import android.widget.TextView;import android.widget.AdapterView.OnItemSelectedListener;public class MainActivity extends Activity {  private ListView listview;  private ProgressBar loadBar;  private TextView loadText;  private ShopAdapter adapter;  private int start=0; //开始数量  private int limit=3; //每页数量  @Override  public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.main);    listview=(ListView)findViewById(R.id.main_ListView);    loadBar=(ProgressBar)findViewById(R.id.main_loadBar);    loadText=(TextView)findViewById(R.id.main_loadText);    adapter=new ShopAdapter(this);    listview.setAdapter(adapter);    listview.setOnItemSelectedListener(new OnItemSelectedListener(){      @Override      public void onItemSelected(AdapterView arg0, View arg1,      int count, long arg3) {        if(adapter.getCount()==count+1){          loadText.setText("下载中...");          loadBar.setVisibility(View.VISIBLE);          new Thread(mRunnable).start();        }      }      @Override      public void onNothingSelected(AdapterView arg0) {      }    });    new Thread(mRunnable).start();  }    private Runnable mRunnable=new Runnable(){    public void run(){      try {        Thread.sleep(1500);        mHandler.sendMessage(mHandler.obtainMessage());      }      catch (InterruptedException e) {        //System.out.println("Error-"+e.getMessage());      }    }  };  Handler mHandler=new Handler(){    public void handleMessage(Message msg){      super.handleMessage(msg);      loadHotShop(limit);    }  };    public void loadHotShop(int limit){    DBLocalService db=new DBLocalService(this);    Cursor cursor=db.querySQL("select * from "+db.TABLE_SHOP+" limit "+start+","+limit,null);    if(cursor.getCount()>0) this.start+=limit;    while(cursor.moveToNext()){      Shop s=new Shop();      s.setId(cursor.getString(cursor.getColumnIndex("id")));      s.setTitle(cursor.getString(cursor.getColumnIndex("title")));      adapter.addShop(s);    }    loadText.setText("");    loadBar.setVisibility(View.GONE);  }}