Android应用中使用ListView来分页显示刷新的内容

点击按钮刷新1、效果如下：

实例如下： 上图的添加数据按钮可以换成一个进度条 因为没有数据所以我加了一个按钮添加到数据库用于测试；一般在服务器拉去数据需要一定的时间，所以可以弄个进度条来提示用户：点击加载按钮的时候，向数据库读取一次数据，把读取的数据追加到原来的数据集中；然后显示出来

package com.exampleandroid.xiong.listviewpages;  public class News {  private String title;  private int id;   /**   *   * @return 返回新闻标题   */  public String getTitle() {   return title;  }   /**   *   * @param title   *   设置新闻标题   */  public void setTtitle(String title) {   this.title = title;  }   /**   *   * @return 返回新闻标识   */  public int getId() {   return id;  }   /**   *   * @param id   *   设置新闻标识   */  public void setId(int id) {   this.id = id;  } } 

package com.exampleandroid.xiong.listviewpages;  import java.util.ArrayList; import java.util.List; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase;  public class GetNews {   /**   *   * @param page   *   需要加载的页数 每页数据5条   * @param dbnews   *   SQLiteOpenHelper子类   * @return 返回新闻加载的数据   */  public List<News> getListNews(int page, DbSqliteNews dbnews) {   List<News> list = new ArrayList<News>();   String sql = "select * from tb_newstile where news_id not in(select news_id from tb_newstile LIMIT "     + 5 * (page - 1) + ") LIMIT " + 5 * page;   Cursor cursor = dbnews.getReadableDatabase().rawQuery(sql, null);   while (cursor.moveToNext()) {    News news = new News();    news.setTtitle(cursor.getString(1));    news.setId(cursor.getInt(0));    list.add(news);   }   cursor.close();   return list;  }   /**   * 插入100条数据用于测试   *   * @param dbnews   *   SQLiteOpenHelper子类   */  public void insertData(DbSqliteNews dbnews) {   SQLiteDatabase datas = dbnews.getWritableDatabase();   datas.beginTransaction();   try {    for (int i = 0; i < 100; i++) {     datas.execSQL("insert into tb_newstile values(?,?)",       new Object[] { i, "新闻标题" + i });    }    datas.setTransactionSuccessful();   } catch (Exception e) {    System.out.println("数据插入失败！");    e.printStackTrace();   } finally {    datas.endTransaction();   }   } } 

package com.exampleandroid.xiong.listviewpages;  import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteDatabase.CursorFactory; import android.database.sqlite.SQLiteOpenHelper;  public class DbSqliteNews extends SQLiteOpenHelper {   public DbSqliteNews(Context context, String name, CursorFactory factory,    int version) {   super(context, name, factory, version);  }   // 创建数据库表  @Override  public void onCreate(SQLiteDatabase db) {   db.execSQL("create table tb_newstile(news_id integer ,news_title varchar(100))");  }   @Override  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {   }  } 

package com.exampleandroid.xiong.listviewpages;  import java.util.List;  import android.app.Activity; import android.os.Bundle; import android.view.LayoutInflater; import android.view.Menu; import android.view.View; import android.view.View.OnClickListener; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.Button; import android.widget.ImageView; import android.widget.ListView; import android.widget.TextView;  public class MainActivity extends Activity {   private ListView newShow_list;  private Button loadmore, adddata;  // ListView加载的数据  private List<News> shownews;  private GetNews getnews;  private DbSqliteNews dbnews;  // 加载的页数  private int pagecount = 1;   @Override  protected void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   setContentView(R.layout.activity_main);   newShow_list = (ListView) findViewById(R.id.newsShow_list);   loadmore = (Button) findViewById(R.id.loadmore_bt);   adddata = (Button) findViewById(R.id.adddata);   dbnews = new DbSqliteNews(this, "new.db", null, 1);   getnews = new GetNews();   final ListAdpaterNews listadpter=new ListAdpaterNews();   //此按钮只为添加测试数据   adddata.setOnClickListener(new OnClickListener() {     @Override    public void onClick(View v) {     //插入数据     getnews.insertData(dbnews);     //获取数据     shownews = getnews.getListNews(pagecount, dbnews);     //显示数据     newShow_list.setAdapter(listadpter);    }   });   loadmore.setOnClickListener(new OnClickListener() {     @Override    public void onClick(View v) {     pagecount++;     //将数据追加到原集合     shownews.addAll(getnews.getListNews(pagecount, dbnews));     //刷新数据     listadpter.notifyDataSetInvalidated();    }   });   // 第一次加载的数据   shownews = getnews.getListNews(pagecount, dbnews);   newShow_list.setAdapter(listadpter);   }   class ListAdpaterNews extends BaseAdapter {    @Override   public int getCount() {    return pagecount * 5;   }    @Override   public Object getItem(int position) {    return position;   }    @Override   public long getItemId(int position) {    return position;   }    @Override   public View getView(int position, View convertView, ViewGroup parent) {    View view = LayoutInflater.from(MainActivity.this).inflate(      R.layout.news_title, null);    TextView txttitle = (TextView) view.findViewById(R.id.txt_title);    ImageView images = (ImageView) view      .findViewById(R.id.showimage_title);    images.setBackgroundResource(R.drawable.n_me_l);    txttitle.setText(shownews.get(position).getTitle());    return view;   }   }   @Override  public boolean onCreateOptionsMenu(Menu menu) {   getMenuInflater().inflate(R.menu.main, menu);   return true;  }  } 

<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"  tools:context=".MainActivity" >   <ListView   android:id="@+id/newsShow_list"   android:layout_width="match_parent"   android:layout_height="wrap_content" >  </ListView>   <LinearLayout   android:layout_width="match_parent"   android:layout_height="wrap_content"   android:layout_alignParentBottom="true" >    <Button    android:id="@+id/adddata"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:layout_weight="1"    android:text="添加数据" />    <Button    android:id="@+id/loadmore_bt"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:layout_weight="1"    android:text="@string/loadmore" />  </LinearLayout>  </RelativeLayout> 

<?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:padding="15dp"  android:orientation="horizontal" >   <ImageView   android:id="@+id/showimage_title"   android:layout_width="wrap_content"   android:layout_height="wrap_content"   android:background="@drawable/n_me_l"   android:contentDescription="@string/imagenews" />   <TextView   android:id="@+id/txt_title"   android:layout_width="wrap_content"   android:layout_height="wrap_content" />  </LinearLayout> 

下拉刷新当ListView要显示的数据过多时，为了更快的响应用户，这个时候ListView进行分页显示再合适不过了。ListView分页显示数据的原理其实很简单，当用户滑到ListView最后一项时，通知异步线程进行加载下一页的数据，下一页数据加载完成时，调用设置好的Adapter的notifyDataSetChange()方法，ListView显示下一页的数据。现在有两个问题要解决，第一个问题要知道用户是否滑到了ListView的最后一项；第二个问题是如何提示用户正在加载下一页的数据，让用户耐心等待。解决第一个问题，我们只需自定义ListView，让它实现OnScrollListener类监听ListView的滑动状态，以此来判断是否滑动到了最后一项这里只简单说一下要点：

@Override public void onScroll(AbsListView view, int firstVisibleItem,     int visibleItemCount, int totalItemCount ) {    if (getAdapter() == null){     return ;   }     if (getAdapter().getCount() == 0){     return ;   }     int lastItemIndex = firstVisibleItem + visibleItemCount;   if (lastItemIndex >= totalItemCount){     // 用户已经滑动到了ListView的最后一项   } 

要解决第二个问题也是在onScroll()方法中来实现

@Override public void onScroll(AbsListView view, int firstVisibleItem,     int visibleItemCount, int totalItemCount) {    if (getAdapter() == null){     return ;   }     if (getAdapter().getCount() == 0){     return ;   }     int lastItemIndex = firstVisibleItem + visibleItemCount;   if (lastItemIndex >= totalItemCount && ! isLoading){    addFooterView( footerView );//用来提示用户正在加载下一页的数据     isLoading = true ;     listener.loadData();   } 

人生没有彩排，每天都是现场直播。