利用Gallery和ImageView实现图片浏览器

首先，先看一下实现的截图：

如图所示，

其中布局的第一个控件是Gallery,显示的图片滑动浏览，这里用到一个继承自BaseAdapter的类对象，用于填充和显示Gallery中的内容；

布局的第二个控件是ImageView，当用户滑动Gallery时，显示其中的图片，这其中实现了两个重载方法

1.当用户点击Gallery的图片资源时，以Toast的形式告诉用户点击的是哪一幅图片，实现的代码如下：

 /*设定一个itemclickListener并Toast被点选图片的位置*/ 
    g.setOnItemClickListener(new OnItemClickListener() { 
      public void onItemClick(AdapterView<?> parent, View v, int position, long id) { 
        Toast.makeText(EX04_10.this, getString(R.string.my_gallery_text_pre) 
            + position
            + getString(R.string.my_gallery_text_post), Toast.LENGTH_SHORT).show();
        }
      });

2.当Gallery获得焦点时，ImageView显示用户选择的是哪一幅图片，实现的代码如下：

g.setOnItemSelectedListener(new OnItemSelectedListener()
    {

      @Override
      public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2,
          long arg3)
      {
        // TODO Auto-generated method stub
        imageView.setImageResource(myImageIds[arg2]);
        
      }

      @Override
      public void onNothingSelected(AdapterView<?> arg0)
      {
        // TODO Auto-generated method stub
        
      }
    });

下面给出本实例用到的布局文件和具体的实现源代码：

布局文件代码：

<?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/mygallery"
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
/>
<ImageView
    android:id="@+id/imageview"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:scaleType="center"
    />
</LinearLayout>

具体的实现代码：

public class EX04_10 extends Activity { 
  
  /*建构一Integer array并取得预加载Drawable的图片id*/ 
  private Integer[] myImageIds = { R.drawable.photo1, R.drawable.photo2, 
      R.drawable.photo3, R.drawable.photo4, 
      R.drawable.photo5, R.drawable.photo6, };
  

  
  private ImageView imageView;
  /** Called when the activity is first created. */ 
  @Override
  public void onCreate(Bundle savedInstanceState) {
    
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main); 
    
    /*透过findViewById取得*/ 
    Gallery g = (Gallery) findViewById(R.id.mygallery);
    imageView=(ImageView)findViewById(R.id.imageview);
    
    /*新增一ImageAdapter并设定给Gallery对象*/
    g.setAdapter(new ImageAdapter(this)); 
    
    /*设定一个itemclickListener并Toast被点选图片的位置*/ 
    g.setOnItemClickListener(new OnItemClickListener() { 
      public void onItemClick(AdapterView<?> parent, View v, int position, long id) { 
        Toast.makeText(EX04_10.this, getString(R.string.my_gallery_text_pre) 
            + position
            + getString(R.string.my_gallery_text_post), Toast.LENGTH_SHORT).show();
        }
      });
    
    g.setOnItemSelectedListener(new OnItemSelectedListener()
    {

      @Override
      public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2,
          long arg3)
      {
        // TODO Auto-generated method stub
        imageView.setImageResource(myImageIds[arg2]);
        
      }

      @Override
      public void onNothingSelected(AdapterView<?> arg0)
      {
        // TODO Auto-generated method stub
        
      }
    });
    }
  
  
  /*改写BaseAdapter自定义一ImageAdapter class*/ 
  public class ImageAdapter extends BaseAdapter {
    
    int mGalleryItemBackground;
    private Context mContext; 
    
    /*ImageAdapter的建构子*/ 
    public ImageAdapter(Context c) {
      mContext = c; 
      /* 使用在res/values/attrs.xml中的定义 * 的Gallery属性.*/ 
      TypedArray a = obtainStyledAttributes(R.styleable.Gallery);
      /*取得Gallery属性的Index id*/ 
      mGalleryItemBackground = a.getResourceId( R.styleable.Gallery_android_galleryItemBackground, 0);
      /*让对象的styleable属性能够反复使用*/ 
      a.recycle(); 
      } 
    
    /*一定要重写的方法getCount,传回图片数目*/ 
    public int getCount() { 
      return myImageIds.length;
      } 
    
    /*一定要重写的方法getItem,传回position*/ 
    public Object getItem(int position) { 
      return position; 
      } 
    
    /*一定要重写的方法getItemId,传回position*/ 
    public long getItemId(int position) {
      return position; 
      } 
    
    /*一定要重写的方法getView,传回一View对象*/ 
    public View getView(int position, View convertView, ViewGroup parent) { 
      /*产生ImageView对象*/
      ImageView i = new ImageView(mContext); 
      /*设定图片给imageView对象*/ 
      i.setImageResource(myImageIds[position]); 
      /*重新设定图片的宽高*/
      i.setScaleType(ImageView.ScaleType.FIT_XY); 
      /*重新设定Layout的宽高*/ 
      i.setLayoutParams(new Gallery.LayoutParams(136, 110));
      /*设定Gallery背景图*/ 
      i.setBackgroundResource(mGalleryItemBackground); 
      /*传回imageView物件*/ return i;
      } 
  }
   
  }