Android学习笔记_37_ListView批量加载数据和页脚设置

1、在activity_main.xml布局文件中加入ListView控件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <ListView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
         >
    </ListView>

</RelativeLayout>

2、为ListView添加项listview_item.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
     />

</LinearLayout>

3、添加页脚界面footer.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >
    <ProgressBar 
        android:layout_width="50dp" 
        android:layout_height="match_parent"
        style="?android:attr/progressBarStyle"
        android:id="@+id/downloadbar"
        />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:text="数据正在加载中" />

</LinearLayout>

4、后台代码实现：

package com.example.listviewbatch;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class MainActivity extends Activity {
    private static final String TAG="ListMainActivity";
    private ListView listView;
    private List<String> data = new ArrayList<String>();
    private int pageCount=30;
    private int maxPage;
    private boolean loadfinish=true;//加载完毕
    private ArrayAdapter<String> adapter;
    private View footer;//页脚
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        data = DataService.getData(1, pageCount);
        maxPage=DataService.getTotal()/pageCount==0?DataService.getTotal()/pageCount:DataService.getTotal()/pageCount+1;
        listView = (ListView) this.findViewById(R.id.listView);
        adapter = new ArrayAdapter<String>(this,R.layout.listview_item
                ,R.id.textView,data);
        footer =getLayoutInflater().inflate(R.layout.footer, null);
        listView.addFooterView(footer);
        listView.setAdapter(adapter);
        listView.removeFooterView(footer);
        //监听ListView滚动事件
        listView.setOnScrollListener(new MyScrollListener());
    }
    private final class MyScrollListener implements OnScrollListener{

        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {
            Log.i(TAG, "onScrollStateChanged( scrollState: "+scrollState+")");
        }

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem,
                int visibleItemCount, int totalItemCount) {
            Log.i(TAG, "onScroll( firstVisibleItem: "+firstVisibleItem+")"+
                    "visibleItemCount: "+visibleItemCount+")"+
                    "totalItemCount: "+totalItemCount+")");
            //获取屏幕最后行索引
            int lastItemId = listView.getLastVisiblePosition();
            final int total= totalItemCount;
            if((lastItemId+1)==totalItemCount){//换页
                if(totalItemCount>0){
                    int currentPage = totalItemCount/pageCount==0?totalItemCount/pageCount:totalItemCount/pageCount+1;
                    if((currentPage+1)<maxPage && loadfinish){
                        loadfinish=false;
                        listView.addFooterView(footer);
                        //开启子线程获取数据,由于子线程不能更新主线程的UI，所以必须通过Handle进行处理，需要子线程将数据包装
                        //成Message对象，再通过Handle接收到数据，调用notifyDataSetChanged通知适配器更
                        //新ListView
                        new Thread(new Runnable() {
                            @Override
                            public void run() {
                                try {
                                    Thread.sleep(3000);
                                } catch (InterruptedException e) {
                                    e.printStackTrace();
                                }
                                List<String> resultList =DataService.getData(total, pageCount);
                                Log.i("DataServiceGetData","count: "+resultList.size());
                                handler.sendMessage(handler.obtainMessage(0, resultList));
                            }
                        }).start();
                    }
                }
            }
        }
    }
    private Handler handler = new Handler(){
        
        @Override
        public void handleMessage(Message msg) {
            data.addAll((List<String>) msg.obj);
            //通知ListView数据发生改变，要求ListView更新界面
            adapter.notifyDataSetChanged();
            if(listView.getFooterViewsCount()>0){
                listView.removeFooterView(footer);
            }
            loadfinish=true;
        }
        
    };
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

public class DataService {
    public static List<String> getData(int items,int count){
        int j=0;
        List<String>  dataList = new ArrayList<String>();
        for (int i = items; i <= 200;i++) {
            j=j+1;
            if(j<count){
                dataList.add("ListView批量加载数据"+i);
            }
        }
        return dataList;
    }
    public static int getTotal(){
        return 200;
    }
}