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;

    }

}