android 入门 Gallery

package com.zte.android.lesstion;
   
  
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.AdapterView;
import android.widget.Gallery;
import android.widget.Toast;

/**
 * @author rychenga
 * 
 * 水平方向上显示一组图片，以便于浏览
 */
public class Activity_012_Gallery extends Activity
{
	private Gallery gallery ;
	@Override
	protected void onCreate(Bundle savedInstanceState) 
	{
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_012_gallery_layout);
		//init gallery
		gallery = (Gallery)findViewById(R.id.l012_gallery1);
		//设置适配器(datasource)
		Activity_012_ImageAdapter adapter = new Activity_012_ImageAdapter(Activity_012_Gallery.this);
		gallery.setAdapter(adapter);
		//显示被选中部分所处的位置，显示信息持续2秒
		gallery.setOnItemSelectedListener(new OnItemSelectedListener() 
		{
			//覆盖2个默认方法
			public void onItemSelected(AdapterView<?> parent, View view,
					int position, long id) {
				// TODO Auto-generated method stub
				Toast.makeText(Activity_012_Gallery.this,
						"第"+position+"张", 2).show();
			}
			public void onNothingSelected(AdapterView<?> arg0) {
				// TODO Auto-generated method stub
				
			}
		});
	}
}  

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <Gallery
        android:id="@+id/l012_gallery1"
        android:layout_width="match_parent"
        android:layout_height="300dp"/>

</LinearLayout>