Android实现简单的分批加载ListView

每次滑动至底端，从数据库中获取10条数据，并加载于ListView中

数据库

package com.example.listviewbatchloading; 

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper; 

public class PersonDb extends SQLiteOpenHelper { 

  public PersonDb(Context context) {
    super(context, "creature", null, 1);
    // TODO Auto-generated constructor stub
  } 

  @Override
  public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub
    db.execSQL("create table people(_id integer primary key autoincrement,name char,number char)");
  } 

  @Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub
    db.execSQL("drop table people");
    onCreate(db);
  } 

} 

数据库的业务封装，其中获取更多数据的是核心代码

package com.example.listviewbatchloading; 

/**
 * 数据库的业务封装类
 */ 

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

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase; 

public class PersonList { 

  PersonDb personDb; 

  public PersonList(Context context){
    this.personDb = new PersonDb(context);
  } 

  /**
   *   获取一定条目的数据
   * @param startIndex
   *   开始取数据的位置
   * @param num
   *   取多少条数据
   */
  public List<Person> getMoreDatas(int startIndex,int num){ 

    List<Person> list = new ArrayList<Person>();
    SQLiteDatabase db = personDb.getWritableDatabase();
    Cursor cursor = db.rawQuery("select name,number from people order by _id desc limit ?,?",
        new String[]{startIndex + "",num + ""}); 

    while(cursor.moveToNext()){
      Person person = new Person();
      person.setName(cursor.getString(cursor.getColumnIndex("name")));
      person.setNumber(cursor.getString(cursor.getColumnIndex("number")));
      list.add(person);
    } 

    cursor.close();
    db.close(); 

    return list; 

  } 

  /**
   *   添加数据库条目
   * @param name
   * @param number
   */
  public void add(String name,String number){ 

    SQLiteDatabase db = personDb.getWritableDatabase(); 

    ContentValues cv = new ContentValues();
    cv.put("name", name);
    cv.put("number", number); 

    db.insert("people", null, cv);
    db.close();
  } 

} 

功能实现

package com.example.listviewbatchloading; 

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.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast; 

public class MainActivity extends Activity { 

  private ListView lv ;
  private List<Person> datas = new ArrayList<Person>();
  private static int PERPAGE = 10; //每页加载数目
  private static final int FINISH = 0;//数据加载完成
  private List<Person> moreDatas;//每次加载的数据
  private MyAdapter adapter;
  private PersonList personList ; 

  //若数据较多，耗时较长，数据加载完成时，发送FINISH至handler，并通知ListView更新数据
  private Handler handler = new Handler(){
    public void handleMessage(android.os.Message msg) { 

      switch (msg.what) {
      case FINISH:
        if (moreDatas.size() != 0) {
          System.out.println(moreDatas.toString());
          adapter.notifyDataSetChanged();
        }else {
          Toast.makeText(MainActivity.this, "没有更多数据", Toast.LENGTH_SHORT).show();
        }
        break; 

      default:
        break;
      } 

    };
  }; 

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    initView();
    initData();
    initEvent();
  }
  /**
   *   为ListView添加滚动监听事件，但滚动至最后一行时，加载更多数据
   */
  private void initEvent() {
    lv.setOnScrollListener(new OnScrollListener() { 

      @Override
      public void onScrollStateChanged(AbsListView view, int scrollState) {
        // TODO Auto-generated method stub
        if (scrollState == OnScrollListener.SCROLL_STATE_IDLE) {
          int lastVisiblePosition = lv.getLastVisiblePosition();
          if (lastVisiblePosition == datas.size() - 1) {
            initData();
            System.out.println("加载更多数据");
          }
        }
      } 

      @Override
      public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
        // TODO Auto-generated method stub 

      }
    });
  } 

  private void initView() { 

    setContentView(R.layout.activity_main); 

    lv = (ListView) findViewById(R.id.lv);
    personList = new PersonList(getApplicationContext());
    adapter = new MyAdapter();
    lv.setAdapter(adapter);
  } 

  /**
   * 在子线程中加载数据，避免主线程阻塞
   */
  private void initData() {
    new Thread() { 

      public void run() { 

        // 加载更多数据
        moreDatas = personList.getMoreDatas(datas.size(), PERPAGE); 

        datas.addAll(moreDatas);// 把一个容器的所有数据加进来
        // 取数据完成，发消息通知取数据完成
        handler.obtainMessage(FINISH).sendToTarget(); 

      };
    }.start();
  } 

  private class ItemView{
    private TextView tv_name;
    private TextView tv_num;
  } 

  /**
   *   ListView的适配器
   * @author lian
   *
   */
  private class MyAdapter extends BaseAdapter{ 

    @Override
    public int getCount() {
      // TODO Auto-generated method stub
      return datas.size();
    } 

    @Override
    public Object getItem(int position) {
      // TODO Auto-generated method stub
      return null;
    } 

    @Override
    public long getItemId(int position) {
      // TODO Auto-generated method stub
      return 0;
    } 

    @Override
    public View getView(int position, View convertView, ViewGroup parent) { 

      ItemView itemView = null;
      if (convertView == null) {
        itemView = new ItemView();
        convertView = View.inflate(getApplicationContext(), R.layout.item_lv, null);
        itemView.tv_name = (TextView) convertView.findViewById(R.id.tv_name);
        itemView.tv_num = (TextView) convertView.findViewById(R.id.tv_num);
        convertView.setTag(itemView);
      }else {
        itemView = (ItemView) convertView.getTag();
      } 

      Person person = datas.get(position);
      itemView.tv_name.setText(person.getName());
      itemView.tv_num.setText(person.getNumber()); 

      return convertView;
    } 

  } 

}

其他Person的JavaBean，以及布局文件，不在赘述

以上就是本文的全部内容，希望对大家的学习有所帮助。