ListView动态加载-简单易懂

package com.demo; import java.util.List; import android.app.Activity; import android.os.Bundle; import android.os.Handler; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.AbsListView; import android.widget.BaseAdapter; import android.widget.ListView; import android.widget.TextView; import android.widget.Toast; import android.widget.AbsListView.OnScrollListener; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; public class MainActivity extends Activity implements OnScrollListener,OnItemClickListener { private ListView listView; private List<String> currentData;//当前视图显示的数据 private CustomAdapter customadapter;//自定义适配器 private View loadingView;//加载视图的布局 private int currentPage = 1;//当前页,默认为1 private int pageSize = 10;//每页显示十条信息 private int last_item_position;//最后item的位置 private boolean isLoading = false;//是否加载过,控制加载次数 public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); listView=(ListView)findViewById(R.id.lv_id); //加载视图布局 loadingView = LayoutInflater.from(this).inflate(R.layout.list_page_load, null); //创建当前用于显示视图的数据 currentData=CreateDataFactory.createUpdateData(currentPage,pageSize); //添加底部加载视图 listView.addFooterView(loadingView); //初始化适配器 customadapter=new CustomAdapter(); listView.setAdapter(customadapter); //滚动条监听 listView.setOnScrollListener(this); //ListView监听 listView.setOnItemClickListener(this); } @Override public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) { last_item_position = firstVisibleItem + visibleItemCount - 1; if(last_item_position==totalItemCount-2){//这里控制当焦点落在某一个位置时,开始加载. //当前是在第9个位置开始加载,改为totalItemCount-1 //则会在第10个位置开始加载 System.out.println("开始加载.."); Toast.makeText(MainActivity.this, "第 "+currentPage+" 页", Toast.LENGTH_LONG).show(); if(!isLoading){ new Thread(){ public void run() { isLoading = true; //开启一个线程加载数据，否则会堵塞当前线程 updateCurrendData(); //发送一个消息,通知数据加载完成 loadingHandler.sendEmptyMessage(0); } }.start(); } } //当ListView没有FooterView时,添加FooterView(---loadingView---) if(listView.getFooterViewsCount()==0){ listView.addFooterView(loadingView); } } @Override public void onScrollStateChanged(AbsListView view, int scrollState) { // TODO Auto-generated method stub } Handler loadingHandler = new Handler(){ public void handleMessage(android.os.Message msg) { //修改adapter count customadapter.count = currentPage*pageSize; //更新 customadapter.notifyDataSetChanged(); //消除MSG loadingHandler.removeMessages(0); //删除FooterView listView.removeFooterView(loadingView); //进入下一页，此时视图未加载. isLoading = false; }; }; //添加List元素 private void updateCurrendData(){ //模拟联接网络以及从网络中获取数据花费的时间 try { Thread.sleep(3000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } //更新一次,当前页加1 currentPage++; //获取当前要更新的数据 List<String> updateDataList = CreateDataFactory.createUpdateData(currentPage, pageSize); //需要更新的数据加入当前数据集合 for(String itemData:updateDataList){ currentData.add(itemData); } } class CustomAdapter extends BaseAdapter{ int count=currentData.size(); @Override public int getCount() { // TODO Auto-generated method stub return count; } @Override public Object getItem(int position) { // TODO Auto-generated method stub return position; } @Override public long getItemId(int position) { // TODO Auto-generated method stub return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { View view=LayoutInflater.from(MainActivity.this).inflate(R.layout.list_page_item, null); TextView tv_content = (TextView) view.findViewById(R.id.tv_content); tv_content.setText(currentData.get(position)); return view; } } @Override public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { // TODO Auto-generated method stub } }