Android中ListView分页加载数据

package com.scott.loadmore;

import java.util.List;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class ListViewAdapter extends BaseAdapter {
	private List<String> items;
	private LayoutInflater inflater;
	
	public ListViewAdapter(Context context, List<String> items) {
		this.items = items;
		inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);		
	}
	
	@Override
	public int getCount() {
		return items.size();
	}

	@Override
	public Object getItem(int position) {
		return items.get(position);
	}

	@Override
	public long getItemId(int position) {
		return position;
	}

	@Override
	public View getView(int position, View view, ViewGroup parent) {
		if (view == null) {
			view = inflater.inflate(R.layout.list_item, null);
		}
		TextView text = (TextView) view.findViewById(R.id.list_item_text);
		text.setText(items.get(position));
		return view;
	}
	
	/**
	 * 添加列表项
	 * @param item
	 */
	public void addItem(String item) {
		items.add(item);
	}
}

package com.scott.loadmore;

import java.util.ArrayList;

import android.app.ListActivity;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.Button;
import android.widget.ListView;

public class MainActivity extends ListActivity implements OnScrollListener {
	private ListView listView;
	private int visibleLastIndex = 0;	//最后的可视项索引
	private int visibleItemCount;		// 当前窗口可见项总数
	private ListViewAdapter adapter;
	private View loadMoreView;
	private Button loadMoreButton;
	private Handler handler = new Handler();

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		
		loadMoreView = getLayoutInflater().inflate(R.layout.load_more, null);
		loadMoreButton = (Button) loadMoreView.findViewById(R.id.loadMoreButton);

		listView = getListView();				//获取id是list的ListView
		
		listView.addFooterView(loadMoreView);	//设置列表底部视图

		initAdapter();
		
		setListAdapter(adapter);				//自动为id是list的ListView设置适配器
		
		listView.setOnScrollListener(this);		//添加滑动监听
	}
	
	/**
	 * 初始化适配器
	 */
	private void initAdapter() {
		ArrayList<String> items = new ArrayList<String>();
		for (int i = 0; i < 10; i++) {
			items.add(String.valueOf(i + 1));
		}
		adapter = new ListViewAdapter(this, items);
	}

	/**
	 * 滑动时被调用
	 */
	@Override
	public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
		this.visibleItemCount = visibleItemCount;
		visibleLastIndex = firstVisibleItem + visibleItemCount - 1;
	}

	/**
	 * 滑动状态改变时被调用
	 */
	@Override
	public void onScrollStateChanged(AbsListView view, int scrollState) {
		int itemsLastIndex = adapter.getCount() - 1;	//数据集最后一项的索引
		int lastIndex = itemsLastIndex + 1;				//加上底部的loadMoreView项
		if (scrollState == OnScrollListener.SCROLL_STATE_IDLE && visibleLastIndex == lastIndex) {
			//如果是自动加载,可以在这里放置异步加载数据的代码
			Log.i("LOADMORE", "loading...");
		}
	}
	
	/**
	 * 点击按钮事件
	 * @param view
	 */
	public void loadMore(View view) {
		loadMoreButton.setText("loading...");	//设置按钮文字loading
		handler.postDelayed(new Runnable() {
			@Override
			public void run() {
				
				loadData();
				
				adapter.notifyDataSetChanged();	//数据集变化后,通知adapter
				listView.setSelection(visibleLastIndex - visibleItemCount + 1);	//设置选中项
				
				loadMoreButton.setText("load more");	//恢复按钮文字
			}
		}, 2000);
	}
	
	/**
	 * 模拟加载数据
	 */
	private void loadData() {
		int count = adapter.getCount();
		for (int i = count; i < count + 10; i++) {
			adapter.addItem(String.valueOf(i + 1));
		}
	}
}