Android入门之Gallery用法实例解析

本文实例介绍的android的gallery控件是个很不错的看图控件，可以大大减轻开发者对于看图功能的开发，并且效果也很美观。本文实例中的gallery的用法，主要实现用反射机制来动态读取资源中的图片。

该实例代码运行的效果图如下：

 

main.xml源码如下:

<?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程序源码如下：

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; 
       
      //用反射机制来获取资源中的图片id和尺寸 
      field[] fields = r.drawable.class.getdeclaredfields(); 
      for (field field : fields) 
      { 
        if (!"icon".equals(field.getname()))//除了icon之外的图片 
        {   
          int index=field.getint(r.drawable.class); 
          //保存图片id 
          imglist.add(index); 
          //保存图片大小 
          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); 
      //从imglist取得图片id 
      i.setimageresource(imglist.get(position).intvalue()); 
      i.setscaletype(imageview.scaletype.fit_xy); 
      //从imgsizes取得图片大小 
      int size[]= new int[2]; 
      size=(int[]) imgsizes.get(position); 
      i.setlayoutparams(new gallery.layoutparams(size[0], size[1])); 
      return i; 
    } 
     
  }; 
}