Android开发之ListView利用OnScrollListener实现分页加载数据

    android:layout_
    android:layout_
    android:orientation="vertical" >
        android:id="@+id/bt_load"    
      android:layout_    
      android:layout_  
      android:text="加载更多数据" /> 
        android:id="@+id/pg"
      android:layout_
      android:layout_
      android:layout_gravity="center_horizontal"
      android:visibility="gone"
      />

    android:layout_
    android:layout_
    android:orientation="vertical" >
    
            android:id="@+id/tv_title"
        android:textSize="20sp"
        android:layout_
        android:layout_
        android:layout_marginTop="5dp"
        />
            android:textSize="12sp"
        android:id="@+id/tv_content"
        android:layout_
        android:layout_
        android:layout_marginTop="5dp"
        />

package com.notice.moredate;

import java.util.ArrayList;
import java.util.HashMap;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.SimpleAdapter;
import android.widget.Toast;

public class MoreDateListActivity extends Activity implements OnScrollListener {
    
    // ListView的Adapter
    private SimpleAdapter mSimpleAdapter;
    private ListView lv;
    private Button bt;
    private ProgressBar pg;
    private ArrayList> list;
    // ListView底部View
    private View moreView;
    private Handler handler;
    // 设置一个最大的数据条数，超过即不再加载
    private int MaxDateNum;
    // 最后可见条目的索引
    private int lastVisibleIndex;
    
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        
        MaxDateNum = 22; // 设置最大数据条数

        lv = (ListView) findViewById(R.id.lv);

        // 实例化底部布局
        moreView = getLayoutInflater().inflate(R.layout.moredate, null);

        bt = (Button) moreView.findViewById(R.id.bt_load);
        pg = (ProgressBar) moreView.findViewById(R.id.pg);
        handler = new Handler();

        // 用map来装载数据，初始化10条数据
        list = new ArrayList>();
        for (int i = 0; i <10; i++) {
            HashMap map = new HashMap();
            map.put("ItemTitle", "第" + i + "行标题");
            map.put("ItemText", "第" + i + "行内容");
            list.add(map);
        }
        // 实例化SimpleAdapter
        mSimpleAdapter = new SimpleAdapter(this, list, R.layout.item,
                new String[] { "ItemTitle", "ItemText" },
                new int[] { R.id.tv_title, R.id.tv_content });
        // 加上底部View，注意要放在setAdapter方法前
        lv.addFooterView(moreView);
        lv.setAdapter(mSimpleAdapter);
        // 绑定监听器
        lv.setOnScrollListener(this);

        bt.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                pg.setVisibility(View.VISIBLE);// 将进度条可见
                bt.setVisibility(View.GONE);// 按钮不可见

                handler.postDelayed(new Runnable() {

                    @Override
                    public void run() {
                        loadMoreDate();// 加载更多数据
                        bt.setVisibility(View.VISIBLE);
                        pg.setVisibility(View.GONE);
                        mSimpleAdapter.notifyDataSetChanged();// 通知listView刷新数据
                    }

                }, 2000);
            }
        });

    }

    private void loadMoreDate() {
        int count = mSimpleAdapter.getCount();
        if (count + 5             // 每次加载5条
            for (int i = count; i                 HashMap map = new HashMap();
                map.put("ItemTitle", "新增第" + i + "行标题");
                map.put("ItemText", "新增第" + i + "行内容");
                list.add(map);
            }
        } else {
            // 数据已经不足5条
            for (int i = count; i                 HashMap map = new HashMap();
                map.put("ItemTitle", "新增第" + i + "行标题");
                map.put("ItemText", "新增第" + i + "行内容");
                list.add(map);
            }
        }

    }
   /** 
            * firstVisibleItem 表示在当前屏幕显示的第一个listItem在整个listView里面的位置（下标从0开始） 
            * visibleItemCount表示在现时屏幕可以见到的ListItem(部分显示的ListItem也算)总数 
            * totalItemCount表示ListView的ListItem总数  
            * listView.getLastVisiblePosition()表示在现时屏幕最后一个ListItem 
            * (最后ListItem要完全显示出来才算)在整个ListView的位置（下标从0开始）  
            */      @Override
    public void onScroll(AbsListView view, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) {
        // 计算最后可见条目的索引
        lastVisibleIndex = firstVisibleItem + visibleItemCount - 1;

        // 所有的条目已经和最大条数相等，则移除底部的View
        if (totalItemCount == MaxDateNum + 1) {
            lv.removeFooterView(moreView);
            Toast.makeText(this, "数据全部加载完成，没有更多数据！", Toast.LENGTH_LONG).show();
        }

    }

 /**
    *scrollState有三种状态，分别是SCROLL_STATE_IDLE、SCROLL_STATE_TOUCH_SCROLL、SCROLL_STATE_FLING
    *SCROLL_STATE_IDLE是当屏幕停止滚动时
    *SCROLL_STATE_TOUCH_SCROLL是当用户在以触屏方式滚动屏幕并且手指仍然还在屏幕上时（The user is scrolling using touch, and their finger is still on the screen）
    *SCROLL_STATE_FLING是当用户由于之前划动屏幕并抬起手指，屏幕产生惯性滑动时（The user had previously been scrolling using touch and had performed a fling）
    */      @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
        // 滑到底部后自动加载，判断listview已经停止滚动并且最后可视的条目等于adapter的条目
        if (scrollState == OnScrollListener.SCROLL_STATE_IDLE
                && lastVisibleIndex == mSimpleAdapter.getCount()) {
            // 当滑到底部时自动加载
            // pg.setVisibility(View.VISIBLE);
            // bt.setVisibility(View.GONE);
            // handler.postDelayed(new Runnable() {
            //
            // @Override
            // public void run() {
            // loadMoreDate();
            // bt.setVisibility(View.VISIBLE);
            // pg.setVisibility(View.GONE);
            // mSimpleAdapter.notifyDataSetChanged();
            // }
            //
            // }, 2000);

        }

    }
    
}