Android入门第十二篇之Gallery

Android的Gallery控件是个很不错的看图控件，大大减轻了开发者对于看图功能的开发，而且效果也比较美观。本文介绍Gallery的用法，用反射机制来动态读取资源中的图片。

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main.xml源码:

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程序源码：

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1. package?com.testImageView;????
2. import?java.lang.reflect.Field;??import?java.util.ArrayList;??
3. ??import?android.app.Activity;??
4. import?android.content.Context;??import?android.graphics.Bitmap;??
5. import?android.graphics.BitmapFactory;??import?android.os.Bundle;??
6. import?android.view.View;??import?android.view.ViewGroup;??
7. import?android.widget.AdapterView;??import?android.widget.BaseAdapter;??
8. import?android.widget.Gallery;??import?android.widget.ImageView;??
9. import?android.widget.AdapterView.OnItemClickListener;????
10. public?class?testImageView?extends?Activity?{??????private?Gallery?mGallery;??
11. ????@Override??????public?void?onCreate(Bundle?savedInstanceState)?{??
12. ????????super.onCreate(savedInstanceState);??????????setContentView(R.layout.main);??
13. ??????????????????mGallery?=?(Gallery)findViewById(R.id.gallery);??
14. ????????try?{??????????????mGallery.setAdapter(new?ImageAdapter(this));??
15. ????????}?catch?(IllegalArgumentException?e)?{??????????????//?TODO?Auto-generated?catch?block??
16. ????????????e.printStackTrace();??????????}?catch?(IllegalAccessException?e)?{??
17. ????????????//?TODO?Auto-generated?catch?block??????????????e.printStackTrace();??
18. ????????}??????????mGallery.setOnItemClickListener(new?OnItemClickListener()?{??
19. ????????????public?void?onItemClick(AdapterView?parent,?View?v,?int?position,?long?id)?{??????????????????testImageView.this.setTitle(String.valueOf(position));??
20. ????????????}??????????});??
21. ????}????????
22. ????/*??????*?class?ImageAdapter?is?used?to?control?gallery?source?and?operation.?
23. ?????*/??????private?class?ImageAdapter?extends?BaseAdapter{??
24. ????????private?Context?mContext;??????????private?ArrayList<Integer>?imgList=new?ArrayList<Integer>();??
25. ????????private?ArrayList<Object>?imgSizes=new?ArrayList<Object>();??????????public?ImageAdapter(Context?c)?throws?IllegalArgumentException,?IllegalAccessException{??
26. ????????????mContext?=?c;????????????????
27. ????????????//用反射机制来获取资源中的图片ID和尺寸??????????????Field[]?fields?=?R.drawable.class.getDeclaredFields();??
28. ????????????for?(Field?field?:?fields)??????????????{??
29. ????????????????if?(!"icon".equals(field.getName()))//除了icon之外的图片??????????????????{?????
30. ????????????????????int?index=field.getInt(R.drawable.class);??????????????????????//保存图片ID??
31. ????????????????????imgList.add(index);??????????????????????//保存图片大小??
32. ????????????????????int?size[]=new?int[2];??????????????????????Bitmap?bmImg=BitmapFactory.decodeResource(getResources(),index);??
33. ????????????????????size[0]=bmImg.getWidth();size[1]=bmImg.getHeight();??????????????????????imgSizes.add(size);??
34. ????????????????}??????????????}??
35. ????????}??????????@Override??
36. ????????public?int?getCount()?{??????????????//?TODO?Auto-generated?method?stub??
37. ??????????????return?imgList.size();??
38. ????????}????
39. ????????@Override??????????public?Object?getItem(int?position)?{??
40. ????????????//?TODO?Auto-generated?method?stub????
41. ????????????return?position;??????????}??
42. ??????????@Override??
43. ????????public?long?getItemId(int?position)?{??????????????//?TODO?Auto-generated?method?stub??
44. ??????????????return?position;??
45. ????????}????
46. ????????@Override??????????public?View?getView(int?position,?View?convertView,?ViewGroup?parent)?{??
47. ????????????//?TODO?Auto-generated?method?stub????
48. ????????????ImageView?i?=?new?ImageView?(mContext);??????????????//从imgList取得图片ID??
49. ????????????i.setImageResource(imgList.get(position).intValue());??????????????i.setScaleType(ImageView.ScaleType.FIT_XY);??
50. ????????????//从imgSizes取得图片大小??????????????int?size[]=?new?int[2];??
51. ????????????size=(int[])?imgSizes.get(position);??????????????i.setLayoutParams(new?Gallery.LayoutParams(size[0],?size[1]));??
52. ????????????return?i;??????????}??
53. ??????????????};??
54. }?