Android中动态更新ListView

在使用ListView时，会遇到当ListView列表滑动到最底端时，添加新的列表项的问题，本文通过代码演示如何动态的添加新的列表项到ListView中。
实现步骤：调用ListView的setOnScrollListener()方法设置滑动监听器，实现OnScrollListener接口的方法，判断当列表滑动到最低端时，加载新的列表项。
其中OnScrollListener接口需要实现如下两个方法：
onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount)
view 报告滑动状态的视图
firstVisibleItem 可视的第一个列表项的索引
visibleItemCount 可视的列表项个数
totalItemCount 总共的列表项个数
onScrollStateChanged(AbsListView view, int scrollState)
view 报告滑动状态的视图
scrollState 滑动状态
滑动状态包括
SCROLL_STATE_IDLE : 0 视图没有滑动
SCROLL_STATE_TOUCH_SCROLL : 1 用户正在触摸滑动，手指仍在屏幕上
SCROLL_STATE_FLING : 2 用户之前触摸滑动，现在正在滑行，直到停止
下面通过代码给大家演示效果
main.xml

<?xml version="1.0" encoding="utf-8"?>  

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
     android:orientation="vertical" 
     android:layout_width="fill_parent" 
     android:layout_height="fill_parent" 
     >  
     <ListView 
         android:id="@id/android:list" 
         android:layout_width="match_parent" 
         android:layout_height="match_parent" 
         android:layout_weight="1" 
         android:drawSelectorOnTop="false" 
         />  
</LinearLayout> 

footer.xml

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
		android:layout_width="fill_parent" 
		android:layout_height="wrap_content" 
       		android:gravity="center" 
		android:orientation="horizontal" 
	>  
	<ProgressBar 
	 	android:id="@+id/progressbar" 
	        android:layout_width="wrap_content" 
		android:layout_height="wrap_content" 
		style="\?android:attr/progressBarStyleSmall" 
		/>  
	<TextView 
		android:layout_width="wrap_content" 
		android:layout_height="wrap_content" 
		android:textSize="20.0sp" 
		android:text="正在加载..." 
		/>  
	</LinearLayout> 

 

MainActicity.xml

package com.szy.listview;  
import android.app.ListActivity;  
import android.os.Bundle;  
import android.os.Handler;  
import android.os.Message;  
import android.view.Gravity;  
import android.view.View;  
import android.view.ViewGroup;  
import android.widget.AbsListView;  
import android.widget.BaseAdapter;  
import android.widget.ListView;  
import android.widget.TextView;  

public class MainActivity extends ListActivity  
{  
	private ListView mListView;  
	private CustomAdapter mAdapter;  
	private int mScrollState;  
	private View mFooter;  
	@Override 
	public void onCreate(Bundle savedInstanceState)  
	{  
		super.onCreate(savedInstanceState);  
		setContentView(R.layout.main);  
		//获取ListView  
		mListView = getListView();  
		//根据footer.xml描述创建View  
		mFooter = getLayoutInflater().inflate(R.layout.footer, null);  
		// 在ListView底部添加正在加载视图  
		//注意：addFooterView方法需要在调用setListAdapter方法前调用！  
		mListView.addFooterView(mFooter);  
		mAdapter = new CustomAdapter();  
		setListAdapter(mAdapter);  
		//给ListView添加滚动监听器  
		mListView.setOnScrollListener(new AbsListView.OnScrollListener()  
		{  
		@Override 
		public void onScrollStateChanged(AbsListView view, int scrollState)  
		{  
			//记录当前状态  
			 mScrollState = scrollState;  
		}  
		@Override 
		public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount)  
		{  
			// 可视的最后一个列表项的索引  
			int lastVisibleItem = firstVisibleItem + visibleItemCount - 1;  
			 //当列表正处于滑动状态且滑动到列表底部时，执行  
			 if (mScrollState != AbsListView.OnScrollListener.SCROLL_STATE_IDLE&& lastVisibleItem == totalItemCount - 1)  
			 {  
			// 执行线程，模拟睡眠5秒钟后添加10个列表项  
				new Thread()  
				{  
					 private Handler handler = new Handler()  
					{  
					 @Override 
						public void handleMessage(Message msg)  
						{  
							super.handleMessage(msg);  
							//增加Item数量  
							mAdapter.count += 10;  
							//通知数据集变化  
							mAdapter.notifyDataSetChanged();  
						}  
					};  
					 @Override 
					public void run()  
					{  
						super.run();  
						try 
						{  
							sleep(5000);  
							handler.sendEmptyMessage(0);  
						 } catch (InterruptedException e)  
						{  
							e.printStackTrace();  
						}  
					 }  
				}.start();  
			}  
		 }  
	});  
}  
private class CustomAdapter extends BaseAdapter  
{  
	// 初始列表项数量  
	int count = 20;   
	public int getCount()  
	{  
		return count;  
	}  
	public Object getItem(int position)  
	{  
		return position;  
	}  
	public long getItemId(int position)  
	{  
		return position;  
	}  

	public View getView(int position, View convertView, ViewGroup parent)  
	{  
		TextView result = (TextView) convertView;  
		//动态创建TextView添加早ListView中  
		if (result == null)  
		{  
			result = new TextView(MainActivity.this);  
			result.setTextAppearance(MainActivity.this, android.R.style.TextAppearance_Large);  
			AbsListView.LayoutParams layoutParams = new AbsListView.LayoutParams(AbsListView.LayoutParams.FILL_PARENT,AbsListView.LayoutParams.WRAP_CONTENT);  
			result.setLayoutParams(layoutParams);  
			result.setGravity(Gravity.CENTER);  
		}  
		result.setText("第 " + (position + 1)+"行");  
		return result;  
	}  
	}  
}