ScrollView滑动到最底端或者最顶端再加载数据

要实现一个功能：当Scrollview滑动到最底端的时候需要触发事件加载其他数据。很多人都以为ScrollView可以像ListViev那样setOnScrollListener，其实沒那么简单，因为ScrollView压根就没有该接口，在baidu上兜了一圈没有找到合适的答案，没办法只能google去了，居然一下子解决了这个问题，还是老外比较牛，呵呵，这是我访问的网址： 
http://stackoverflow.com/questions/2864563/how-do-i-know-that-the-scrollview-is-already-scrolled-to-the-bottom 

注意，如果数据不满一页的话，会执行onBottom方法！通常要使用懒加载的话数据都会超过一页，所以我沒仔细考虑这个问题！ 

我把ScrollView封装成类了，源码如下： 

[java] view plaincopyprint?

1. package com.ql.view;  
2.   
3. import android.content.Context;  
4. import android.os.Handler;  
5. import android.os.Message;  
6. import android.util.AttributeSet;  
7. import android.view.MotionEvent;  
8. import android.view.View;  
9. import android.widget.ScrollView;  
10.    
11. public class LazyScrollView extends ScrollView{  
12.     private static final String tag="LazyScrollView";  
13.     private Handler handler;  
14.     private View view;  
15.     public LazyScrollView(Context context) {  
16.         super(context);  
17.         // TODO Auto-generated constructor stub  
18.     }  
19.     public LazyScrollView(Context context, AttributeSet attrs) {  
20.         super(context, attrs);  
21.         // TODO Auto-generated constructor stub  
22.     }  
23.     public LazyScrollView(Context context, AttributeSet attrs, int defStyle) {  
24.         super(context, attrs, defStyle);  
25.         // TODO Auto-generated constructor stub  
26.     }  
27.     //这个获得总的高度  
28.     public int computeVerticalScrollRange(){  
29.         return super.computeHorizontalScrollRange();  
30.     }  
31.     public int computeVerticalScrollOffset(){  
32.         return super.computeVerticalScrollOffset();  
33.     }  
34.     private void init(){  
35.           
36.         this.setOnTouchListener(onTouchListener);  
37.         handler=new Handler(){  
38.             @Override  
39.             public void handleMessage(Message msg) {  
40.                 // process incoming messages here  
41.                 super.handleMessage(msg);  
42.                 switch(msg.what){  
43.                 case 1:  
44.                     if(view.getMeasuredHeight() <= getScrollY() + getHeight()) {  
45.                         if(onScrollListener!=null){  
46.                             onScrollListener.onBottom();  
47.                         }  
48.                           
49.                     }else if(getScrollY()==0){  
50.                         if(onScrollListener!=null){  
51.                             onScrollListener.onTop();  
52.                         }  
53.                     }  
54.                     else{  
55.                         if(onScrollListener!=null){  
56.                             onScrollListener.onScroll();  
57.                         }  
58.                     }  
59.                     break;  
60.                 default:  
61.                     break;  
62.                 }  
63.             }  
64.         };  
65.           
66.     }  
67.       
68.       OnTouchListener onTouchListener=new OnTouchListener(){  
69.   
70.             @Override  
71.             public boolean onTouch(View v, MotionEvent event) {  
72.                 // TODO Auto-generated method stub  
73.                 switch (event.getAction()) {  
74.                 case MotionEvent.ACTION_DOWN:  
75.                     break;  
76.                 case MotionEvent.ACTION_UP:  
77.                     if(view!=null&&onScrollListener!=null){  
78.                         handler.sendMessageDelayed(handler.obtainMessage(1), 200);  
79.                     }  
80.                     break;  
81.   
82.                 default:  
83.                     break;  
84.                 }  
85.                 return false;  
86.             }  
87.               
88.         };  
89.           
90.         /** 
91.          * 获得参考的View，主要是为了获得它的MeasuredHeight，然后和滚动条的ScrollY+getHeight作比较。 
92.          */  
93.         public void getView(){  
94.             this.view=getChildAt(0);  
95.             if(view!=null){  
96.                 init();  
97.             }  
98.         }  
99.           
100.         /** 
101.          * 定义接口 
102.          * @author admin 
103.          * 
104.          */  
105.         public interface OnScrollListener{  
106.             void onBottom();  
107.             void onTop();  
108.             void onScroll();  
109.         }  
110.         private OnScrollListener onScrollListener;  
111.         public void setOnScrollListener(OnScrollListener onScrollListener){  
112.             this.onScrollListener=onScrollListener;  
113.         }  
114. }  

用的时候也很简单，通常这样使用： 

[java] view plaincopyprint?

1. scrollView=(LazyScrollView)findViewById(R.id.scrollView);  
2.         scrollView.getView();  
3.         scrollView.setOnScrollListener(new OnScrollListener() {  
4.               
5.             @Override  
6.             public void onTop() {  
7.                 // TODO Auto-generated method stub  
8.                 Log.d(tag,"------滚动到最上方------");  
9.             }  
10.               
11.             @Override  
12.             public void onScroll() {  
13.                 // TODO Auto-generated method stub  
14.                 Log.d(tag,"没有到最下方，也不是最上方");  
15.             }  
16.               
17.             @Override  
18.             public void onBottom() {  
19.                 // TODO Auto-generated method stub  
20.                 Log.d(tag,"------滚动到最下方------");  
21.             }  
22.         });  

感激我吧，我呕心沥血才出来了这么个类。呵呵。 

顺便记一下老外使用fullScroll的做法。当然也可以直接fullScroll而不需要放入post()。 

[java] view plaincopyprint?

1. scrollView.post(new Runnable() {     
2.            @Override    
3.            public void run() {     
4.             scrollView.fullScroll(View.FOCUS_DOWN);     
5.            }     
6.        });