画廊视图(Gallery)的功能和用法

Gallery与Spinner组件有共同的父类：AbsSpinner，表明Gallery和Spinner都是一个列表框。它们之间的区别在于Spinner显示的是一个垂直的列表选择框吗，而Gallery显示的是一个水平的列表选择框。

下面以一个例子来说明：

activity_main.xml

<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/imageView"

	    android:layout_width="match_parent"

	    android:layout_height="0dip"

	    android:layout_weight="1"/>

	<Gallery

	    android:id="@+id/gallery"

	    android:layout_width="match_parent"

	    android:layout_height="wrap_content"

	    android:layout_marginTop="25dip"

	    android:unselectedAlpha="0.6"

	    android:spacing="2pt"/>

</LinearLayout>

MainActivity.java

package com.example.testgallary;

import android.app.Activity;

import android.content.res.TypedArray;

import android.os.Bundle;

import android.view.View;

import android.view.ViewGroup;

import android.widget.AdapterView;

import android.widget.AdapterView.OnItemSelectedListener;

import android.widget.BaseAdapter;

import android.widget.Gallery;

import android.widget.ImageView;

public class MainActivity extends Activity {

	private int[] imageIds = new int[]{

			R.drawable.img1, R.drawable.img2,

			R.drawable.img3, R.drawable.img4,

			R.drawable.img5, R.drawable.img6,

	};

	private Gallery gallery;

	private ImageView imageView;

	@Override

	protected void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);

		setContentView(R.layout.activity_main);

		gallery = (Gallery) findViewById(R.id.gallery);

		imageView = (ImageView) findViewById(R.id.imageView);

		BaseAdapter adapter = new BaseAdapter() {

			@Override

			public View getView(int position, View convertView, ViewGroup parent) {

				// 创建一个ImageView

				ImageView imageView = new ImageView(MainActivity.this);

				imageView.setImageResource(imageIds[position]);

				// 设置ImageView的缩放类型

				imageView.setScaleType(ImageView.ScaleType.FIT_XY);

				// 为imageView设置布局参数

				imageView.setLayoutParams(new Gallery.LayoutParams(75, 100));

				TypedArray typedArray = obtainStyledAttributes(

						R.styleable.Gallery);

				imageView.setBackgroundResource(typedArray.getResourceId(

						R.styleable.Gallery_android_galleryItemBackground, 0));

				return imageView;

			}

			@Override

			public long getItemId(int position) {

				// TODO Auto-generated method stub

				return position;

			}

			@Override

			public Object getItem(int item) {

				// TODO Auto-generated method stub

				return item;

			}

			@Override

			public int getCount() {

				// TODO Auto-generated method stub

				return imageIds.length;

			}

		};

		gallery.setAdapter(adapter);

		gallery.setOnItemSelectedListener(new OnItemSelectedListener() {

			@Override

			public void onItemSelected(AdapterView<?> parent, View view,

					int position, long id) {

				imageView.setImageResource(imageIds[position]);

			}

			@Override

			public void onNothingSelected(AdapterView<?> view) {

			}

		});

	}

}

运行结果：