Android实现幻灯片式图片浏览器

package com.example.test;  
  
import android.app.Activity; 
import android.content.res.TypedArray; 
import android.os.Bundle; 
import android.view.View; 
import android.view.ViewGroup; 
import android.view.ViewGroup.LayoutParams; 
import android.view.animation.AnimationUtils; 
import android.widget.AdapterView; 
import android.widget.AdapterView.OnItemSelectedListener; 
import android.widget.BaseAdapter; 
import android.widget.Gallery; 
import android.widget.ImageSwitcher; 
import android.widget.ImageView; 
import android.widget.ViewSwitcher.ViewFactory; 
  
public class MainActivity extends Activity {  
  //定义并初始化保存图片id的数组 
   private int[] imageId=new int[]{R.drawable.img1,R.drawable.img2,R.drawable.img3,R.drawable.img4, 
       R.drawable.img5,R.drawable.img6,R.drawable.img7,R.drawable.img8,R.drawable.img9}; 
   //声明一个图像切换器对象 
   private ImageSwitcher imageSwitcher; 
  @Override  
  public void onCreate(Bundle savedInstanceState) {  
    super.onCreate(savedInstanceState);  
    setContentView(R.layout.main);  
      
    Gallery gallery=(Gallery)findViewById(R.id.gallery1);//获取gallery组件 
     
    imageSwitcher=(ImageSwitcher)findViewById(R.id.imageSwitcher);//获取图像切换器 
    //设置动画效果 
    imageSwitcher.setInAnimation(AnimationUtils.loadAnimation(this, 
        android.R.anim.fade_in));//设置淡入动画 
    imageSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,  
        android.R.anim.fade_out));//设置淡出动画 
    imageSwitcher.setFactory(new ViewFactory(){ 
 
 
      @Override 
      public View makeView() { 
        ImageView imageView=new ImageView(MainActivity.this);//实例化一个imageView类的对象 
        imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);//设置保持纵横比居中缩放图像 
        imageView.setLayoutParams(new ImageSwitcher.LayoutParams( 
            LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT)); 
        return imageView;//返回imageView对象 
      } 
    }); 
     
    BaseAdapter adapter=new BaseAdapter(){ 
 
 
      @Override 
      public View getView(int position, View convertView, ViewGroup parent) { 
        ImageView imageView;//声明ImageView的对象 
        if(convertView==null){ 
          imageView=new ImageView(MainActivity.this);//实例化ImageView的对象 
          imageView.setScaleType(ImageView.ScaleType.FIT_XY);//设置缩放方式 
          imageView.setLayoutParams(new Gallery.LayoutParams(180,135)); 
          //设置gallery每一项图片的背景资源(使用的是attr.xml的自定义样式) 
          TypedArray typedArray=obtainStyledAttributes(R.styleable.Gallery); 
          imageView.setBackgroundResource(typedArray.getResourceId( 
              R.styleable.Gallery_android_galleryItemBackground, 0)); 
           
          imageView.setPadding(5, 0, 5, 0);//设置imageView的内边距 
        }else{ 
          imageView=(ImageView)convertView; 
        } 
        imageView.setImageResource(imageId[position]);//为imageView设置要显示的图片 
        return imageView;//返回ImageView 
      } 
       
      //功能:获得当前选项的id 
      @Override 
      public long getItemId(int position) { 
        return position; 
      } 
       
      //功能：获得当前选项 
      @Override 
      public Object getItem(int position) { 
        return position; 
      } 
       
      //获得数量 
      @Override 
      public int getCount() { 
        return imageId.length; 
      } 
    }; 
     
    gallery.setAdapter(adapter);//将适配器与Gallery关联 
    gallery.setSelection(imageId.length/2);//选中中间的图片 
    gallery.setOnItemSelectedListener(new OnItemSelectedListener() { 
 
 
      @Override 
      public void onItemSelected(AdapterView parent, View v, 
          int position, long id) { 
        imageSwitcher.setImageResource(imageId[position]);//显示选中的图片 
      } 
 
 
      @Override 
      public void onNothingSelected(AdapterView arg0) { 
        // TODO Auto-generated method stub 
      } 
    }); 
  }  
}