Android gallery与BaseaDapter的使用

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >        <ImageView         android:id="@+id/img"        android:layout_width="300dp"        android:layout_height="300dp"        android:layout_gravity="center"        />    <Gallery         android:id="@+id/gallery"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:spacing="3dp"        android:layout_gravity="bottom"        /></LinearLayout>

package com.example.test;import android.app.Activity;import android.content.Context;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;public class MainActivity extends Activity {    private Gallery mGallery;    private ImageView mImg;    //图片数组    private int[] pics = {            R.drawable.girl1,            R.drawable.girl2,            R.drawable.girl4,            R.drawable.gril3,            R.drawable.demo,            R.drawable.demo1    };    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        mImg = (ImageView)findViewById(R.id.img);        mGallery = (Gallery)findViewById(R.id.gallery);        MyAdapter adapter = new MyAdapter(this);        mGallery.setAdapter(adapter);        mGallery.setOnItemClickListener(new Gallery.OnItemClickListener()        {            @Override            public void onItemClick(AdapterView<?> adapter, View view, int position,                    long arg3) {                mImg.setImageResource(pics[position]);            }                    });    }        //内部类    class MyAdapter extends BaseAdapter    {        //用来接收传递过来的Context上下文对象        private Context context;        //构造函数        public MyAdapter(Context context)        {            this.context = context;        }        @Override        public int getCount() {            //返回图片数组大小            return pics.length;        }        @Override        public Object getItem(int position) {            //根据选中项返回索引位置            return position;        }        @Override        public long getItemId(int position) {            //根据选中项id返回索引位置            return position;        }        //未优化的getView，这部分可以使用recycle()释放内存、或者BitmapFacotry.Options缩小，或者软引用，或者控制图片资源大小等等很多方法，找时间专门写        @Override        public View getView(int position, View convertView, ViewGroup parent) {            ImageView img = new ImageView(context);            img.setAdjustViewBounds(true);            img.setImageResource(pics[position]);            img.setScaleType(ImageView.ScaleType.FIT_XY);//            img.setLayoutParams(new Gallery.LayoutParams(120,120));                        return img;        }        }}

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