Android listview怎么实现滚动分页

package com.test;

import android.app.ListActivity;
import android.os.Bundle;
import android.os.Handler;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.LinearLayout.LayoutParams;

public class test extends ListActivity implements OnScrollListener {
        Aleph0 adapter = new Aleph0();
        int lastItem = 0;
        int mProgressStatus = 0;
        private Handler mHandler = new Handler();
        ProgressBar progressBar;

        protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                LinearLayout searchLayout = new LinearLayout(this);
                searchLayout.setOrientation(LinearLayout.HORIZONTAL);
                progressBar = new ProgressBar(this);
                progressBar.setPadding(0, 0, 15, 0);
                searchLayout.addView(progressBar, new LinearLayout.LayoutParams(
                                LinearLayout.LayoutParams.WRAP_CONTENT,
                                LinearLayout.LayoutParams.WRAP_CONTENT));
                TextView textView = new TextView(this);
                textView.setText("加载中...");
                textView.setGravity(Gravity.CENTER_VERTICAL);
                searchLayout.addView(textView, new LinearLayout.LayoutParams(