实现原理：在onItemSelected事件中，选中galerry中的图片时，把选中的图片放大，把没有选中的缩小。
以下是关键代码
1 public void onItemSelected(AdapterView<?> parent, View view, int position, 2 long id) { 3 // 选中Gallery中某个图像时，放大显示该图像 4 ImageView imageview = (ImageView)view; 5 ((ImageView) view).setImageDrawable((Drawable) product_image_list.get(position)); 6 view.setLayoutParams( new Gallery.LayoutParams(520 / 2, 318 / 2)); 7 title.setText((String)product_title.get(position)); 8 info.setText((String)product_info.get(position)); 9 for( int i=0; i<parent.getChildCount();i++){ 10 // 缩小选中图片旁边的图片 11 ImageView local_imageview = (ImageView)parent.getChildAt(i); 12 if(local_imageview!=imageview){ 13 local_imageview.setLayoutParams( new Gallery.LayoutParams(520/4, 318/4)); 14 local_imageview.setScaleType(ImageView.ScaleType.FIT_CENTER); 15 } 16 } 17 } 18 19 public void onNothingSelected(AdapterView<?> parent) 20 { 21 } 22 23 public class ImageAdapter extends BaseAdapter 24 { 25 int mGalleryItemBackground; 26 private Context mContext; 27 28 public ImageAdapter(Context context) 29 { 30 mContext = context; 31 // TypedArray typedArray = obtainStyledAttributes(R.styleable.Gallery); 32 // mGalleryItemBackground = typedArray.getResourceId( 33 // R.styleable.Gallery_android_galleryItemBackground, 0); 34 } 35 36 public int getCount() 37 { 38 return product_image_list.size(); 39 } 40 41 public Object getItem( int position) 42 { 43 return position; 44 } 45 46 public long getItemId( int position) 47 { 48 return position; 49 } 50 51 public View getView( int position, View convertView, ViewGroup parent) 52 { 53 ImageView imageView = new ImageView(mContext); 54 imageView.setLayoutParams( new Gallery.LayoutParams(520/4, 318/4));//默认都是大图 55 imageView.setImageDrawable((Drawable) product_image_list.get(position)); 56 imageView.setScaleType(ImageView.ScaleType.FIT_CENTER); 57 return imageView; 58 } 59 }