ListView中的滚动事件及自动翻页功能

ListView的滚动事件

             为ListView添加滚动事件
           setOnScrollListener(OnScrollListener listener)
  OnScrollListener
         void onScrollStateChanged(AbsListView view,int scrollState)
      SCROLL_STATE_IDLE

                       SCROLL_STATE_TOUCH_SCROLL
      SCROLL_STATE_FLING
 void Scroll(AbsListView view,int firstVisibleItem,int visibleItemCounyt,
        int totalItemCount)

ListView滑动到底部自动翻页
      要点
         为自定义适配器，添加追加数据集的方法
 为ListView添加滚动事件监听器
      在onScroll方法中计算lastVisibleItem

   在onScrollStateChanged方法中，判断是否滑动到底部，如果滑动到底部加载新数据，并刷新listview

下面是一个能够实现自动翻页功能的小项目

主Activity：

          package com.example.listview1;

import java.util.ArrayList;

import android.app.Activity;
import android.app.AlertDialog;
import android.os.Bundle;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;

public class MainActivity extends Activity {
private ListView lvMusics;
private MusicAdapter adapter;
private int page;
private AlertDialog dialog;

private void setupView(){
lvMusics = (ListView) findViewById(R.id.lvMusics);
page = 1;
adapter = new MusicAdapter(this, MusicBiz.getMusics(page++));
lvMusics.setAdapter(adapter);

}

private void addListener(){
lvMusics.setOnScrollListener(new OnScrollListener() {

private int lastVisibleItem;

@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
// TODO Auto-generated method stub
if(scrollState == OnScrollListener.SCROLL_STATE_IDLE
&& lastVisibleItem == adapter.getCount() - 1){
//加载新数据
ArrayList<Music> musics = MusicBiz.getMusics(page++);
adapter.addData(musics);
}
}

@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
// TODO Auto-generated method stub
// 计算当前可见的最后一个Item
lastVisibleItem = firstVisibleItem + visibleItemCount - 1;
}
});
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setupView();
addListener();
}
}

                      

实现的对象：

       

       为了省事，代码几乎跟前几次一样。。。。。。

        package com.example.listview1;

public class Music {
private String name;
private String album;
private int id;
private String duration;
private String artist;
private String musicPath;
private String albumPicPath;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAlbum() {
return album;
}
public void setAlbum(String album) {
this.album = album;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getDuration() {
return duration;
}
public void setDuration(String duration) {
this.duration = duration;
}
public String getArtist() {
return artist;
}
public void setArtist(String artist) {
this.artist = artist;
}
public String getMusicPath() {
return musicPath;
}
public void setMusicPath(String musicPath) {
this.musicPath = musicPath;
}
public String getAlbumPicPath() {
return albumPicPath;
}
public void setAlbumPicPath(String albumPicPath) {
this.albumPicPath = albumPicPath;
}

public String toString(){
return "Music [id=" + id +
",name=" + name + ",album=" + album +
",duration=" + duration + ",artist=" + artist +
",musicPath=" + musicPath + ",albumPicPath="
+ albumPicPath + "]";
}
}


    适配器几乎也没有变化：
                         package com.example.listview1;

import java.util.ArrayList;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class MusicAdapter extends BaseAdapter {
private ArrayList<Music> musics;
private LayoutInflater inflater;

public MusicAdapter(Context context,ArrayList<Music> musics) {
if(musics != null)
this.musics = musics;
else
this.musics = new ArrayList<Music>();
this.inflater = LayoutInflater.from(context);
}

public void addData(ArrayList<Music> musics){
if(musics != null){
this.musics.addAll(musics);
notifyDataSetChanged();
}
}

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

@Override
public Music getItem(int position) {
// TODO Auto-generated method stub
return musics.get(position);
}

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

@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub

ViewHolder holder = null;

if(convertView == null){
convertView = inflater.inflate(R.layout.item, null);
holder = new ViewHolder();
holder.tvName = (TextView)convertView.findViewById(R.id.tvName);
holder.tvAlbum = (TextView)convertView.findViewById(R.id.tvAlbum);
holder.tvArtist = (TextView)convertView.findViewById(R.id.tvArtist);
holder.tvDuration = (TextView)convertView.findViewById(R.id.tvDuration);

convertView.setTag(holder);
}else{
holder = (ViewHolder)convertView.getTag();
}

Music m = musics.get(position);
holder.tvName.setText(m.getName());
holder.tvAlbum.setText(m.getAlbum());
holder.tvArtist.setText(m.getArtist());
holder.tvDuration.setText(m.getDuration());

return convertView;

}

class ViewHolder{
private TextView tvName;
private TextView tvDuration;
private TextView tvArtist;
private TextView tvAlbum;
}

}

操作者同样的一组数据：

           package com.example.listview1;

import java.util.ArrayList;

public class MusicBiz {
public static ArrayList<Music> getMusics(int page){
ArrayList<Music> musics = new ArrayList<Music>();
int i=(page - 1) * 20 +1;
int end = i+20;
for(;i<end;i++){
Music m = new Music();
m.setId(i);
m.setName("歌曲" + i);
m.setAlbum("专辑" + i);
m.setAlbumPicPath("D:/www.123/123/1.jpg");
m.setDuration("14:23");
m.setArtist("陈奕迅");
m.setMusicPath("http://www.123wer/123/music.jpg");
musics.add(m);
}

return musics;
}
}

布局相同：

        <ListView
android:id="@+id/lvMusics"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
/>
<?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" >
<ImageView
android:layout_width="64dp"
android:layout_height="64dp"
android:src="@drawable/image"/>
<TableLayout
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1.0"
android:stretchColumns="*">
<TableRow
android:layout_height="0dp"
android:layout_weight="1.0">
<TextView
android:id="@+id/tvName"
android:layout_height="match_parent"
android:gravity="center_vertical"
android:textSize="20sp"/>
<TextView
android:id="@+id/tvDuration"
android:layout_height="match_parent"
android:gravity="center_vertical"
android:textSize="20sp"/>
</TableRow>
<TableRow
android:layout_height="0dp"
android:layout_weight="1.0">
<TextView
android:id="@+id/tvArtist"
android:layout_height="match_parent"
android:gravity="center_vertical"
android:textSize="20sp"/>
<TextView
android:id="@+id/tvAlbum"
android:layout_height="match_parent"
android:gravity="center_vertical"
android:textSize="20sp"/>
</TableRow>
</TableLayout>
</LinearLayout>