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。

       本文的效果图：

 

main.xml源码:

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1. <? xml   version = "1.0"   encoding = "utf-8" ?>   
2. < LinearLayout   xmlns:android = "http://schemas.android.com/apk/res/android"   
3.     android:orientation = "vertical"   
4.     android:layout_width = "fill_parent"   
5.     android:layout_height = "fill_parent"   
6.     >   
7. < Gallery   android:id = "@+id/gallery"   android:layout_height = "fill_parent"   android:layout_width = "fill_parent" > </ Gallery >   
8. </ LinearLayout >   

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <Gallery android:id="@+id/gallery" android:layout_height="fill_parent" android:layout_width="fill_parent"></Gallery> </LinearLayout>

 

程序源码：

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1. package  com.testImageView;  
2.   
3. import  java.lang.reflect.Field;  
4. import  java.util.ArrayList;  
5.   
6. import  android.app.Activity;  
7. import  android.content.Context;  
8. import  android.graphics.Bitmap;  
9. import  android.graphics.BitmapFactory;  
10. import  android.os.Bundle;  
11. import  android.view.View;  
12. import  android.view.ViewGroup;  
13. import  android.widget.AdapterView;  
14. import  android.widget.BaseAdapter;  
15. import  android.widget.Gallery;  
16. import  android.widget.ImageView;  
17. import  android.widget.AdapterView.OnItemClickListener;  
18.   
19. public   class  testImageView  extends  Activity {  
20.     private  Gallery mGallery;  
21.     @Override   
22.     public   void  onCreate(Bundle savedInstanceState) {  
23.         super .onCreate(savedInstanceState);  
24.         setContentView(R.layout.main);  
25.           
26.         mGallery = (Gallery)findViewById(R.id.gallery);  
27.         try  {  
28.             mGallery.setAdapter(new  ImageAdapter( this ));  
29.         } catch  (IllegalArgumentException e) {  
30.             // TODO Auto-generated catch block   
31.             e.printStackTrace();  
32.         } catch  (IllegalAccessException e) {  
33.             // TODO Auto-generated catch block   
34.             e.printStackTrace();  
35.         }  
36.         mGallery.setOnItemClickListener(new  OnItemClickListener() {  
37.             public   void  onItemClick(AdapterView parent, View v,  int  position,  long  id) {  
38.                 testImageView.this .setTitle(String.valueOf(position));  
39.             }  
40.         });  
41.     }  
42.       
43.     /*  
44.      * class ImageAdapter is used to control gallery source and operation.  
45.      */   
46.     private   class  ImageAdapter  extends  BaseAdapter{  
47.         private  Context mContext;  
48.         private  ArrayList<Integer> imgList= new  ArrayList<Integer>();  
49.         private  ArrayList<Object> imgSizes= new  ArrayList<Object>();  
50.         public  ImageAdapter(Context c)  throws  IllegalArgumentException, IllegalAccessException{  
51.             mContext = c;  
52.               
53.             //用反射机制来获取资源中的图片ID和尺寸   
54.             Field[] fields = R.drawable.class .getDeclaredFields();  
55.             for  (Field field : fields)  
56.             {  
57.                 if  (! "icon" .equals(field.getName())) //除了icon之外的图片   
58.                 {     
59.                     int  index=field.getInt(R.drawable. class );  
60.                     //保存图片ID   
61.                     imgList.add(index);  
62.                     //保存图片大小   
63.                     int  size[]= new   int [ 2 ];  
64.                     Bitmap bmImg=BitmapFactory.decodeResource(getResources(),index);  
65.                     size[0 ]=bmImg.getWidth();size[ 1 ]=bmImg.getHeight();  
66.                     imgSizes.add(size);  
67.                 }  
68.             }  
69.         }  
70.         @Override   
71.         public   int  getCount() {  
72.             // TODO Auto-generated method stub   
73.   
74.             return  imgList.size();  
75.         }  
76.   
77.         @Override   
78.         public  Object getItem( int  position) {  
79.             // TODO Auto-generated method stub   
80.   
81.             return  position;  
82.         }  
83.   
84.         @Override   
85.         public   long  getItemId( int  position) {  
86.             // TODO Auto-generated method stub   
87.   
88.             return  position;  
89.         }  
90.   
91.         @Override   
92.         public  View getView( int  position, View convertView, ViewGroup parent) {  
93.             // TODO Auto-generated method stub   
94.   
95.             ImageView i = new  ImageView (mContext);  
96.             //从imgList取得图片ID   
97.             i.setImageResource(imgList.get(position).intValue());  
98.             i.setScaleType(ImageView.ScaleType.FIT_XY);  
99.             //从imgSizes取得图片大小   
100.             int  size[]=  new   int [ 2 ];  
101.             size=(int []) imgSizes.get(position);  
102.             i.setLayoutParams(new  Gallery.LayoutParams(size[ 0 ], size[ 1 ]));  
103.             return  i;  
104.         }  
105.           
106.     };  
107. }