1、技术要点
listView.setSelection(int postion);定位到listview的具体某个条目。
listView.addHeaderView(view view);向listview头部添加view
listView.addFooterView(view);向listview底部添加view
listView.setOnScrollListener(this);给listview添加滚动事件，一遍监听滚动位置。
如果滚动到顶部，则把头部view显示出来，刷新数据。
如果滚动到底部view显示出来，实现数据加载。
2、实例
package com.example.test;
import java.util.ArrayList;
import java.util.HashMap;
import android.app.Activity;
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.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity1 extends Activity implements OnScrollListener {
private static final String TAG = "MainActivity";
private ListView listView;
private View moreView,moreViewheader; //加载更多页面
private SimpleAdapter adapter;
private ArrayList<HashMap<String, String>> listData;
private int lastItem;
private int count;
private int firstVisibleItem;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main1);
listView = (ListView) findViewById(R.id.listView);
moreView = getLayoutInflater().inflate(R.layout.load1, null);
moreViewheader = getLayoutInflater().inflate(R.layout.load, null);
listData = new ArrayList<HashMap<String, String>>();
listView.setDivider(null);
prepareData(); // 准备数据
count = listData.size();
adapter = new SimpleAdapter(this, listData, R.layout.item,
new String[] { "itemText" }, new int[] { R.id.itemText });
listView.addHeaderView(moreViewheader);
listView.addFooterView(moreView); // 添加底部view，一定要在setAdapter之前添加，否则会报错。
listView.setAdapter(adapter); // 设置adapter
listView.setSelection(1);
listView.setOnScrollListener(this); // 设置listview的滚动事件
}
private void prepareData() { // 准备数据
for (int i = 0; i < 10; i++) {
HashMap<String, String> map = new HashMap<String, String>();
map.put("itemText", "测试数据" + i);
listData.add(map);
}
}
private void loadMoreData() { // 加载更多数据
count = adapter.getCount();
for (int i = count; i < count + 5; i++) {
HashMap<String, String> map = new HashMap<String, String>();
map.put("itemText", "测试数据more---" + i);
listData.add(map);
}
count = listData.size();
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
Log.i(TAG, "firstVisibleItem=" + firstVisibleItem
+ ",,visibleItemCount=" + visibleItemCount + ",,,totalItemCount"
+ totalItemCount);
this.firstVisibleItem=firstVisibleItem;
lastItem = this.firstVisibleItem + visibleItemCount-2; // 减1是因为上面加了个addFooterView
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
Log.i(TAG, "scrollState=" + scrollState);
// 下拉到空闲是，且最后一个item的数等于数据的总数时，进行更新
System.out.println(lastItem +"===="+ count);
if (lastItem == count && scrollState == this.SCROLL_STATE_IDLE) {
Log.i(TAG, "拉到最底部");
moreView.setVisibility(View.VISIBLE);
mHandler.sendEmptyMessage(0);
}
if(this.firstVisibleItem==0){
((TextView)moreViewheader.findViewById(R.id.button1)).setText("正在刷新...");
moreViewheader.setVisibility(View.VISIBLE);
mHandler.sendEmptyMessage(1);
}
}
// 声明Handler
private Handler mHandler = new Handler() {
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case 0:
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
loadMoreData(); // 加载更多数据，这里可以使用异步加载
adapter.notifyDataSetChanged();
moreView.setVisibility(View.GONE);
Log.i(TAG, "加载更多数据");
listView.setSelection(lastItem);
break;
case 1:
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
adapter.notifyDataSetChanged();
moreViewheader.setVisibility(View.GONE);
listView.setSelection(1);
break;
default:
break;
}
};
};
}
2、使用开源框架pulltorefresh，到github搜索。
原文地址：http://cbg23.blog.51cto.com/7201812/1630128
