GridView 与ImageAdapter （笔记）

xml布局文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.graidtest.MainActivity" >
	
    <GridView 
        android:id="@+id/gridView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:columnWidth="90dp"
        android:numColumns="auto_fit"
        android:verticalSpacing="10dp"
        android:horizontalSpacing="10dp"
        android:stretchMode="columnWidth"
        android:gravity="center"/>
    
</RelativeLayout>

MainActivity.java:

public class MainActivity extends ActionBarActivity {

	private GridView gridView;
	private ImageAdapter adapter;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		gridView = (GridView) findViewById(R.id.gridView);
		adapter = new ImageAdapter();
		gridView.setAdapter(adapter);
		gridView.setOnItemClickListener(new OnItemClickListener() {

			@Override
			public void onItemClick(AdapterView<?> parent, View view,
					int position, long id) {
				Toast.makeText(MainActivity.this, "--->>" + position, 1).show();
			}
		});
	}

	private int[] imgs = { R.drawable.ic_launcher, R.drawable.ic_launcher,
			R.drawable.ic_launcher, R.drawable.ic_launcher,
			R.drawable.ic_launcher, R.drawable.ic_launcher,
			R.drawable.ic_launcher, R.drawable.ic_launcher, };

	public class ImageAdapter extends BaseAdapter {

		@Override
		public int getCount() {
			return imgs.length;
		}

		@Override
		public Object getItem(int position) {
			return imgs[position];
		}

		@Override
		public long getItemId(int position) {
			return position;
		}

		@Override
		public View getView(int position, View convertView, ViewGroup parent) {
			// 手工创建view对象 或
			// 加载xml
			ImageView imageView = null;
			if (convertView == null) {
				imageView = new ImageView(MainActivity.this);
			} else {
				imageView = (ImageView) convertView;
			}
			// 设置gridView显示的间距
			imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
			imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
			imageView.setPadding(8, 8, 8, 8);
			imageView.setImageResource(imgs[position]);
			return imageView;
		}

	}

}