gallary和imageswitcher

public class AndroidImageSwitcher  extends Activity implements ViewFactory {
private ImageSwitcher is;  
    private Gallery gallery;  
    private int downX,upX;  
    private ArrayList<Integer> imgList=new ArrayList<Integer>();//图像ID  
      

    protected void onCreate(Bundle savedInstanceState) {  
        // TODO Auto-generated method stub  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.imageswitchview);  
        //用反射机制来获取资源中的图片ID  
        Field[] fields = R.drawable.class.getDeclaredFields();  
        for (Field field : fields)  
        {  
            if (!"icon".equals(field.getName()))//除了icon之外的图片  
            {     
                int index = 0;  
                try {  
                    index = field.getInt(R.drawable.class);  
                } catch (IllegalArgumentException e) {  
                    // TODO Auto-generated catch block  
                    e.printStackTrace();  
                } catch (IllegalAccessException e) {  
                    // TODO Auto-generated catch block  
                    e.printStackTrace();  
                }  
                //保存图片ID  
                imgList.add(index);  
            }  
        }  
          
        //设置ImageSwitcher控件  
        is = (ImageSwitcher) findViewById(R.id.switcher);  
        is.setFactory(this);  
        is.setInAnimation(AnimationUtils.loadAnimation(this,  
                android.R.anim.fade_in));  
        is.setOutAnimation(AnimationUtils.loadAnimation(this,  
                android.R.anim.fade_out));  
        is.setOnTouchListener(new OnTouchListener(){  
            /* 
             * 在ImageSwitcher控件上滑动可以切换图片 
             */ 
     
            public boolean onTouch(View v, MotionEvent event) {  
                if(event.getAction()==MotionEvent.ACTION_DOWN)  
                {  
                    downX=(int) event.getX();//取得按下时的坐标  
                    return true;  
                }  
                else if(event.getAction()==MotionEvent.ACTION_UP)  
                {  
                    upX=(int) event.getX();//取得松开时的坐标  
                    int index=0;  
                    if(upX-downX>100)//从左拖到右，即看前一张  
                    {  
                        //如果是第一，则去到尾部  
                        if(gallery.getSelectedItemPosition()==0)  
                           index=gallery.getCount()-1;  
                        else 
                            index=gallery.getSelectedItemPosition()-1;  
                    }  
                    else if(downX-upX>100)//从右拖到左，即看后一张  
                    {  
                        //如果是最后，则去到第一  
                        if(gallery.getSelectedItemPosition()==(gallery.getCount()-1))  
                            index=0;  
                        else 
                            index=gallery.getSelectedItemPosition()+1;  
                    }  
                    //改变gallery图片所选，自动触发ImageSwitcher的setOnItemSelectedListener  
                    gallery.setSelection(index, true);  
                    return true;  
                }  
                return false;  
            }  
              
        });  
          
        //设置gallery控件  
        gallery = (Gallery) findViewById(R.id.gallery);  
        gallery.setAdapter(new ImageAdapter(this));  
        gallery.setOnItemSelectedListener(new OnItemSelectedListener(){  

            public void onItemSelected(AdapterView<?> arg0, View arg1,  
                    int position, long arg3) {  
                is.setImageResource(imgList.get(position));  
            }  
           
            public void onNothingSelected(AdapterView<?> arg0) {  
                // TODO Auto-generated method stub  
            }  
              
        });  
    }  
    //设置ImgaeSwitcher  
 
    public View makeView() {  
        ImageView i = new ImageView(this);  
        i.setBackgroundColor(0xFF000000);  
        i.setScaleType(ImageView.ScaleType.CENTER);//居中  
        i.setLayoutParams(new ImageSwitcher.LayoutParams(//自适应图片大小  
                LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));  
        return i;  
    }  
    public class ImageAdapter extends BaseAdapter {  
        public ImageAdapter(Context c) {  
            mContext = c;  
        }  
        public int getCount() {  
            return imgList.size();  
        }  
        public Object getItem(int position) {  
            return position;  
        }  
        public long getItemId(int position) {  
            return position;  
        }  
        public View getView(int position, View convertView, ViewGroup parent) {  
            ImageView i = new ImageView(mContext);  
            i.setImageResource(imgList.get(position));  
            i.setAdjustViewBounds(true);  
            i.setLayoutParams(new Gallery.LayoutParams(  
                    LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));  
            return i;  
        }  
        private Context mContext;  
    }