Android入門之Gallery用法實例解析

本文實例介紹的Android的Gallery控件是個很不錯的看圖控件，可以大大減輕開發者對於看圖功能的開發，並且效果也很美觀。本文實例中的Gallery的用法，主要實現用反射機制來動態讀取資源中的圖片。

該實例代碼運行的效果圖如下：

main.xml源碼如下:

<?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>

Java程序源碼如下：

package com.testImageView; 
 
import java.lang.reflect.Field; 
import java.util.ArrayList; 
 
import android.app.Activity; 
import android.content.Context; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.os.Bundle; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.AdapterView; 
import android.widget.BaseAdapter; 
import android.widget.Gallery; 
import android.widget.ImageView; 
import android.widget.AdapterView.OnItemClickListener; 
 
public class testImageView extends Activity { 
  private Gallery mGallery; 
  @Override 
  public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
     
    mGallery = (Gallery)findViewById(R.id.gallery); 
    try { 
      mGallery.setAdapter(new ImageAdapter(this)); 
    } catch (IllegalArgumentException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } catch (IllegalAccessException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } 
    mGallery.setOnItemClickListener(new OnItemClickListener() { 
      public void onItemClick(AdapterView parent, View v, int position, long id) { 
        testImageView.this.setTitle(String.valueOf(position)); 
      } 
    }); 
  } 
   
  /* 
   * class ImageAdapter is used to control gallery source and operation. 
   */ 
  private class ImageAdapter extends BaseAdapter{ 
    private Context mContext; 
    private ArrayList<Integer> imgList=new ArrayList<Integer>(); 
    private ArrayList<Object> imgSizes=new ArrayList<Object>(); 
    public ImageAdapter(Context c) throws IllegalArgumentException, IllegalAccessException{ 
      mContext = c; 
       
      //用反射機制來獲取資源中的圖片ID和尺寸 
      Field[] fields = R.drawable.class.getDeclaredFields(); 
      for (Field field : fields) 
      { 
        if (!"icon".equals(field.getName()))//除了icon之外的圖片 
        {   
          int index=field.getInt(R.drawable.class); 
          //保存圖片ID 
          imgList.add(index); 
          //保存圖片大小 
          int size[]=new int[2]; 
          Bitmap bmImg=BitmapFactory.decodeResource(getResources(),index); 
          size[0]=bmImg.getWidth();size[1]=bmImg.getHeight(); 
          imgSizes.add(size); 
        } 
      } 
    } 
    @Override 
    public int getCount() { 
      // TODO Auto-generated method stub 
 
      return imgList.size(); 
    } 
 
    @Override 
    public Object getItem(int position) { 
      // TODO Auto-generated method stub 
 
      return position; 
    } 
 
    @Override 
    public long getItemId(int position) { 
      // TODO Auto-generated method stub 
 
      return position; 
    } 
 
    @Override 
    public View getView(int position, View convertView, ViewGroup parent) { 
      // TODO Auto-generated method stub 
 
      ImageView i = new ImageView (mContext); 
      //從imgList取得圖片ID 
      i.setImageResource(imgList.get(position).intValue()); 
      i.setScaleType(ImageView.ScaleType.FIT_XY); 
      //從imgSizes取得圖片大小 
      int size[]= new int[2]; 
      size=(int[]) imgSizes.get(position); 
      i.setLayoutParams(new Gallery.LayoutParams(size[0], size[1])); 
      return i; 
    } 
     
  }; 
}