ListView分页加载

技术要点：源码地址：http://download.youkuaiyun.com/detail/anlidengshiwei/8576857点击打开链接

1、  对于加载更多按钮布局的添加和释放，添加是在创建界面的时候就该添加上去，对于出去的判断应该在ListView的setOnScrollListener事件中去完成。通过在OnScroll事件中去判断是否加载到最后一个view，如果是则将加载更多对话框移出。

2、  由于数据量大，对于ListView的每次convertView进行处理，通过ViewHoder进行处理。减少FindViewById的次数。

3、  代码中涉及到的几个变量，一个是总的item条数，一个是可视的最后一个item的index，还有就是每页的显示个数。

4、  对加载更多按钮的处理，当点击加载更多的时候，需要重新往ListView的apdater中去添加数据，然后注册Adapter的notifyDataSetChanged事件。

布局文件：

1、ListView的item的布局文件

<?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:layout_marginTop="3dp"
    android:layout_marginLeft="3dp"
    android:layout_marginRight="3dp"
    android:layout_marginBottom="5dp"
    android:orientation="horizontal" >
    <ImageView 
        android:id="@+id/iv_icon"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/close"/>
	<TextView 
	    android:id="@+id/tv_content"
	    android:layout_width="match_parent"
	    android:layout_height="wrap_content"
	    android:text="This is content"
	    android:textSize="20sp"/>
</LinearLayout>

2、点击加载的Button的布局文件：

<?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" >
    <Button 
        android:id="@+id/btn_load"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="加载更多......" />

</LinearLayout>

3、主界面的布局文件：

<?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" >
    
	<ListView 
	    android:id="@+id/lv_news"
	    android:layout_width="fill_parent"
	    android:layout_height="wrap_content"/>
</LinearLayout>

至此布局文件已经完成。

1、定义一个显示的实体：

public class News {
	private int icon;
	private String content;
	public int getIcon() {
		return icon;
	}
	public void setIcon(int icon) {
		this.icon = icon;
	}
	public String getContent() {
		return content;
	}
	public void setContent(String content) {
		this.content = content;
	}
}

2、定义需要的成员变量：

<span style="white-space:pre">	</span>private ListView lv_news;
	private News news;
	//最后一个的值
	private int visiableLastIndex;
	//每页的可见个数
	private int visiableCount;
	//总共数据个数
	private int dataSize = 50;
	private View loadView;
	private Button btn_loadMore;
	private MyAdapter myAdapter; 
	private Handler handler = new Handler();

3、定义ListView的适配器：

<span style="white-space:pre">	</span>class MyAdapter extends BaseAdapter{
		private List<News> list;
		
		public MyAdapter(List<News> newsList){
			this.list = newsList;
		}
		@Override
		public int getCount() {
			return list == null ? 0 : list.size();
		}

		@Override
		public Object getItem(int position) {
			return list.get(position);
		}

		@Override
		public long getItemId(int position) {
			return position;
		}

		@Override
		public View getView(int position, View convertView, ViewGroup parent) {
			ViewHoder viewHoder;
			if(convertView == null){
				viewHoder = new ViewHoder();
				convertView = ListViewActivity.this.getLayoutInflater().inflate(R.layout.listview_item, null);
				viewHoder.iv_icon = (ImageView) convertView.findViewById(R.id.iv_icon);
				viewHoder.tv_content = (TextView) convertView.findViewById(R.id.tv_content);
				convertView.setTag(viewHoder);
			}else{
				viewHoder = (ViewHoder) convertView.getTag();
			}
			
			if(list != null){
				news = list.get(position);
				viewHoder.iv_icon.setImageResource(news.getIcon());
				viewHoder.tv_content.setText(news.getContent());
			}
			
			return convertView;
		}
		
		public void addItem(News item){
			list.add(item);
		}
		class ViewHoder{
			ImageView iv_icon;
			TextView tv_content;
		}
	}

4、在OnCreate方法中进行初始化控件，并绑定事件：

<span style="white-space:pre">	</span>@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		this.setContentView(R.layout.listview_activity);
		loadView = this.getLayoutInflater().inflate(R.layout.loadmore, null);
		btn_loadMore = (Button) loadView.findViewById(R.id.btn_load);
		btn_loadMore.setOnClickListener(this);
		lv_news = (ListView) this.findViewById(R.id.lv_news);
		lv_news.addFooterView(loadView);
		//初始化Adapter
		initAdapter();
		lv_news.setAdapter(myAdapter);
		lv_news.setOnScrollListener(this);
	}

<pre name="code" class="java"><span style="white-space:pre">	</span>private void initAdapter(){
		List<News> listNews = new ArrayList<News>();
		for(int i=1;i<=10;i++){
			news = new News();
			news.setIcon(R.drawable.close);
			news.setContent("这是新闻内容" + i);
			listNews.add(news);
		}
		myAdapter = new MyAdapter(listNews);
	}

5、重写OnClickListener和OnScrollListener事件：

public class ListViewActivity extends Activity implements OnClickListener,OnScrollListener

<span style="white-space:pre">	</span>@Override
	public void onClick(View v) {
		btn_loadMore.setText("正在加载......");
		handler.postDelayed(new Runnable(){
			@Override
			public void run() {
				loadMoreData();
				myAdapter.notifyDataSetChanged();
				btn_loadMore.setText("查看更多...");
			}
			
		}, 2000);
	}

	private void loadMoreData(){
		int count = myAdapter.getCount();
		int result = count + 10 <= dataSize ? count + 10: dataSize;
		for(int i = count + 1;i<= result; i++){
			news = new News();
			news.setIcon(R.drawable.open);
			news.setContent("这是内容" + i);
			myAdapter.addItem(news);
		}
	}

重写翻页事件

	@Override
	public void onScroll(AbsListView view, int firstVisibleItem,
			int visibleItemCount, int totalItemCount) {
		this.visiableCount = visibleItemCount;
		this.visiableLastIndex = firstVisibleItem + visiableCount -1;
		Log.e("========================= ","========================");  
        Log.e("firstVisibleItem = ",firstVisibleItem+"");  
        Log.e("visibleItemCount = ",visibleItemCount+"");  
        Log.e("totalItemCount = ",totalItemCount+"");  
        Log.e("========================= ","========================");  
      //如果所有的记录选项等于数据集的条数，则移除列表底部视图  
        if(totalItemCount == dataSize+1){  
            lv_news.removeFooterView(loadView);  
            Toast.makeText(this, "数据全部加载完!", Toast.LENGTH_LONG).show();  
        }  
		
	}

	@Override
	public void onScrollStateChanged(AbsListView view, int scrollState) {
		int visiableLastIndex = myAdapter.getCount() -1;
		
	}

至此，已经完成：

参考文档：http://blog.youkuaiyun.com/cjjky/article/details/6898871