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Android應(yīng)用中使用ListView來(lái)分頁(yè)顯示刷新的內(nèi)容

 更新時(shí)間：2016年04月24日 16:22:06   作者：劍蕭舞蝶  
這篇文章主要介紹了Android應(yīng)用中使用ListView來(lái)分頁(yè)顯示刷新的內(nèi)容的方法,展示了一個(gè)點(diǎn)擊按鈕進(jìn)行刷新的實(shí)例以及下拉刷新分頁(yè)顯示的要點(diǎn)解析,需要的朋友可以參考下

點(diǎn)擊按鈕刷新
1、效果如下：

2016424161900539.png (480×854)2016424161920778.jpg (480×854)

實(shí)例如下：  上圖的添加數(shù)據(jù)按鈕可以換成一個(gè)進(jìn)度條  因?yàn)闆](méi)有數(shù)據(jù)所以我加了一個(gè)按鈕添加到數(shù)據(jù)庫(kù)用于測(cè)試；一般在服務(wù)器拉去數(shù)據(jù)需要一定的時(shí)間，所以可以弄個(gè)進(jìn)度條來(lái)提示用戶：
點(diǎn)擊加載按鈕的時(shí)候，向數(shù)據(jù)庫(kù)讀取一次數(shù)據(jù)，把讀取的數(shù)據(jù)追加到原來(lái)的數(shù)據(jù)集中；然后顯示出來(lái)

package com.exampleandroid.xiong.listviewpages; 
 
public class News { 
 private String title; 
 private int id; 
 
 /** 
  * 
  * @return 返回新聞標(biāo)題 
  */ 
 public String getTitle() { 
  return title; 
 } 
 
 /** 
  * 
  * @param title 
  *   設(shè)置新聞標(biāo)題 
  */ 
 public void setTtitle(String title) { 
  this.title = title; 
 } 
 
 /** 
  * 
  * @return 返回新聞標(biāo)識(shí) 
  */ 
 public int getId() { 
  return id; 
 } 
 
 /** 
  * 
  * @param id 
  *   設(shè)置新聞標(biāo)識(shí) 
  */ 
 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 
  *   需要加載的頁(yè)數(shù) 每頁(yè)數(shù)據(jù)5條 
  * @param dbnews 
  *   SQLiteOpenHelper子類 
  * @return 返回新聞加載的數(shù)據(jù) 
  */ 
 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條數(shù)據(jù)用于測(cè)試 
  * 
  * @param dbnews 
  *   SQLiteOpenHelper子類 
  */ 
 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, "新聞標(biāo)題" + i }); 
   } 
   datas.setTransactionSuccessful(); 
  } catch (Exception e) { 
   System.out.println("數(shù)據(jù)插入失?。?); 
   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); 
 } 
 
 // 創(chuàng)建數(shù)據(jù)庫(kù)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加載的數(shù)據(jù) 
 private List<News> shownews; 
 private GetNews getnews; 
 private DbSqliteNews dbnews; 
 // 加載的頁(yè)數(shù) 
 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(); 
  //此按鈕只為添加測(cè)試數(shù)據(jù) 
  adddata.setOnClickListener(new OnClickListener() { 
 
   @Override 
   public void onClick(View v) { 
    //插入數(shù)據(jù) 
    getnews.insertData(dbnews); 
    //獲取數(shù)據(jù) 
    shownews = getnews.getListNews(pagecount, dbnews); 
    //顯示數(shù)據(jù) 
    newShow_list.setAdapter(listadpter); 
   } 
  }); 
  loadmore.setOnClickListener(new OnClickListener() { 
 
   @Override 
   public void onClick(View v) { 
    pagecount++; 
    //將數(shù)據(jù)追加到原集合 
    shownews.addAll(getnews.getListNews(pagecount, dbnews)); 
    //刷新數(shù)據(jù) 
    listadpter.notifyDataSetInvalidated(); 
   } 
  }); 
  // 第一次加載的數(shù)據(jù) 
  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="添加數(shù)據(jù)" /> 
 
  <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
當(dāng)ListView要顯示的數(shù)據(jù)過(guò)多時(shí)，為了更快的響應(yīng)用戶，這個(gè)時(shí)候ListView進(jìn)行分頁(yè)顯示再合適不過(guò)了。
ListView分頁(yè)顯示數(shù)據(jù)的原理其實(shí)很簡(jiǎn)單，當(dāng)用戶滑到ListView最后一項(xiàng)時(shí)，通知異步線程進(jìn)行加載下一頁(yè)的數(shù)據(jù)，下一頁(yè)數(shù)據(jù)加載完成時(shí)，調(diào)用設(shè)置好的Adapter的notifyDataSetChange()方法，ListView顯示下一頁(yè)的數(shù)據(jù)。
現(xiàn)在有兩個(gè)問(wèn)題要解決，第一個(gè)問(wèn)題要知道用戶是否滑到了ListView的最后一項(xiàng)；第二個(gè)問(wèn)題是如何提示用戶正在加載下一頁(yè)的數(shù)據(jù)，讓用戶耐心等待。
解決第一個(gè)問(wèn)題，我們只需自定義ListView，讓它實(shí)現(xiàn)OnScrollListener類監(jiān)聽ListView的滑動(dòng)狀態(tài)，以此來(lái)判斷是否滑動(dòng)到了最后一項(xiàng)
這里只簡(jiǎn)單說(shuō)一下要點(diǎn)：

@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){ 
    // 用戶已經(jīng)滑動(dòng)到了ListView的最后一項(xiàng) 
  }

要解決第二個(gè)問(wèn)題也是在onScroll()方法中來(lái)實(shí)現(xiàn)

@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 );//用來(lái)提示用戶正在加載下一頁(yè)的數(shù)據(jù) 
    isLoading = true ; 
    listener.loadData(); 
  }

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