Android入门第十二篇之Gallery

本文来自http://blog.csdn.net/hellogv/ ，引用必须注明出处！

Android的Gallery控件是个很不错的看图控件，大大减轻了开发者对于看图功能的开发，而且效果也比较美观。本文介绍Gallery的用法，用反射机制来动态读取资源中的图片。

本文的效果图：

main.xml源码:

<?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/gallery" android:layout_height="fill_parent" android:layout_width="fill_parent"></Gallery>
</LinearLayout>

程序源码：

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;
        }
        
    };
}