【Android】动态更新ListView

实现效果：当滑动ListView列表最底端时，动态的添加新的列表项

 

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

 

接口OnScrollListener

 

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

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

 

示例代码：

 

package dyingbleed.iteye;

import android.app.ListActivity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.Gravity;
import android.view.LayoutInflater;
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 Main extends ListActivity {
	
	private ListView listView;
	private MyListViewAdapter adapter;
	
	private int scrollState;
	
	private View footerView;
	
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        listView = getListView();
        
        footerView = LayoutInflater.from(this).inflate(R.layout.progress, null);
        		
        listView.addFooterView(footerView); //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！
        adapter = new MyListViewAdapter();
        setListAdapter(adapter);
        getListView().setOnScrollListener(new AbsListView.OnScrollListener() {
			
			@Override
			public void onScrollStateChanged(AbsListView view, int scrollState) {
				Main.this.scrollState = scrollState;
			}
			
			@Override
			public void onScroll(AbsListView view, int firstVisibleItem,
					int visibleItemCount, int totalItemCount) {
				int lastVisibleItem = firstVisibleItem + visibleItemCount - 1; //可视的最后一个列表项的索引
				/*
				 * 当列表正处于滑动状态且滑动到列表底部时，执行
				 * */
				if(Main.this.scrollState != AbsListView.OnScrollListener.SCROLL_STATE_IDLE
						&& lastVisibleItem == totalItemCount - 1) {
					/*
					 * 执行线程，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);
								adapter.count += 10;
								adapter.notifyDataSetChanged();
							}
							
						};

						@Override
						public void run() {
							super.run();
							try {
								sleep(5000);
								handler.sendEmptyMessage(0);
							} catch (InterruptedException e) {
								e.printStackTrace();
							}
						}
						
					}.start();
					
				}
			}
		});
    }
    
    private class MyListViewAdapter extends BaseAdapter {
    	
    	int count = 50; //初始列表项数量

		@Override
		public int getCount() {
			return count;
		}

		@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) {
			TextView result = (TextView) convertView;
			if(result == null) {
				result = new TextView(Main.this);
				result.setTextAppearance(Main.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("Item "+(position+1));
			return result;
		}
    	
    }
}

 

运行结果