控件：Gallery 3.（实现图片切换）

                                           ◆使用Gallery + ImageSwitcher完成图片浏览功能

grid_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" 
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="#FFFFFF">
    <ImageView
        android:id="@+id/img"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:scaleType="center"/>
</LinearLayout>

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/MyLayout"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:gravity="bottom">
    <ImageSwitcher
        android:id="@+id/myImageSwitcher"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
    <Gallery
        android:id="@+id/myGallery"
        android:gravity="center_vertical"
        android:spacing="3px"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
</LinearLayout>

MyGalleryDemo.java

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Gallery;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.LinearLayout.LayoutParams;
import android.widget.SimpleAdapter;
import android.widget.ViewSwitcher.ViewFactory;

public class MyGalleryDemo extends Activity {
    // 图片浏览
    private Gallery gallery = null;                             
    private List<Map<String,Integer>> list = new ArrayList<Map<String,Integer>>() ;
    private SimpleAdapter simpleAdapter = null;     // 适配器
    private ImageSwitcher myImageSwitcher = null ;    // 图片切换
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // 调用布局文件
        super.setContentView(R.layout.main);    
        // 初始化适配器
        this.initAdapter() ;    
        // 取得组件
        this.gallery = (Gallery) super.findViewById(R.id.myGallery) ;
        // 取得组件
        this.myImageSwitcher = (ImageSwitcher) super.findViewById(R.id.myImageSwitcher);            
        // 设置图片工厂
        this.myImageSwitcher.setFactory(new ViewFactoryImpl()) ;
        // 设置图片集
        this.gallery.setAdapter(this.simpleAdapter);                
        // 设置单击事件
        this.gallery.setOnItemClickListener(new OnItemClickListenerImpl()) ;
    }
    private class OnItemClickListenerImpl implements OnItemClickListener {
        @SuppressWarnings("unchecked")
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,long id) { 
            // 取出Map
            Map<String, Integer> map = (Map<String, Integer>) MyGalleryDemo
                .this.simpleAdapter.getItem(position);                     
            // 设置显示图片
            MyGalleryDemo.this.myImageSwitcher.setImageResource(map.get("img"));                         
        }
    }
    
    // 初始化适配器
    public void initAdapter(){                                    
        Field[] fields = R.drawable.class.getDeclaredFields(); 
        for (int x = 0; x < fields.length; x++) {    
            // 所有ispic_*命名的图片
            if (fields[x].getName().startsWith("ispic_")){         
                // 定义Map
                Map<String,Integer> map = new HashMap<String,Integer>() ;    
                try {
                    // 设置图片资源
                    map.put("img", fields[x].getInt(R.drawable.class)) ;
                } catch (Exception e) {                            
                }
                // 保存Map
                this.list.add(map) ;                            
            }
        }
        // 实例化SimpleAdapter
        this.simpleAdapter = new SimpleAdapter(
                this,             
                this.list,                // 要包装的数据集合
                R.layout.grid_layout,     // 要使用的显示模板
                new String[] { "img" }, // 定义要显示的Map的Key
                new int[] {R.id.img });    // 与模板中的组件匹配
    }
    // 定义视图工厂类
    private class ViewFactoryImpl implements ViewFactory {            
        @Override
        public View makeView() {
            // 实例化图片显示
            ImageView img = new ImageView(MyGalleryDemo.this);    
            // 设置背景颜色
            img.setBackgroundColor(0xFFFFFFFF);        
            // 居中显示
            img.setScaleType(ImageView.ScaleType.CENTER);        
            // 自适应图片大小
            img.setLayoutParams(new ImageSwitcher.LayoutParams(        
                LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));// 定义组件
            return img;
        }
    }

}