android学习之--网格视图(GridView)和图像切换器(ImageSwitcher)

         GridView用于在界面上按行、列分布显示多个组件。GridView和ListView有共同父类：AbsListView。

GridView与ListView的差别在于：ListView仅仅在一个方向上分布，GridView在两个方向上分布。所以使用GridView时一般都指定numColumns大于1，否则该属性默认值为1。就意味着改GridView仅仅有一列，那就变成了ListView

GridView的xml属性

android:strtchMode 的值为：

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     ImageSwitcher由FrameLayout派生而出，ImageSwitcher组件与ImageView非常相似，可是ImageSwitcher多一个功能：它所显示的图片切换时能够设置动画效果。

使用ImageSwitcher时往往须要为它设置一个ImageSwitcher.ViewFactory的makeView()方法来负责显示ImageView

以下结合GridView和ImageSwitcher来实现一个样例

（1）activity_main.xml     布局GridView和ImageSwitcher

<LinearLayout  xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:gravity="center_horizontal">
    <GridView
        android:id="@+id/grid"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:horizontalSpacing="1dp"
        android:verticalSpacing="2dp"
        android:numColumns="4"/>
    <ImageSwitcher
        android:id="@+id/imageSwitch"
        android:layout_gravity="center_vertical|center_horizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

</LinearLayout>

（2）img.xml        布局imageView 用于显示GridView的图片

<?xml version="1.0" encoding="UTF-8"?

>
<LinearLayout  xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <ImageView
        android:id="@+id/img"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
</LinearLayout>

（3）MainActivity.java

package com.example.viewimage;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.GridView;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.ImageView.ScaleType;
import android.widget.SimpleAdapter;
import android.widget.ViewSwitcher.ViewFactory;

public class MainActivity extends Activity {

	//定义组件
	private GridView gredView = null;
	private ImageSwitcher imageSwt =null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		//获取布局组件
		gredView = (GridView) findViewById(R.id.grid);
		imageSwt = (ImageSwitcher) findViewById(R.id.imageSwitch);
		//图片
		final int images[] = new int[]{
				R.drawable.name01,R.drawable.name02,R.drawable.name03,R.drawable.name04,
				R.drawable.name05,R.drawable.name06,R.drawable.name07,R.drawable.name08,
				R.drawable.name09,R.drawable.name10,R.drawable.name11,R.drawable.name12,
				R.drawable.name13,R.drawable.name14,R.drawable.name15,R.drawable.name16
		};
		//创建list集合。存储图片
		List<Map<String,Object>> list = new ArrayList<Map<String,Object>>();
		for(int i=0;i<images.length;i++){
			Map<String,Object> map = new HashMap<String,Object>();
			map.put("img", images[i]);
			list.add(map);
		}
		//设置图片更换效果
		//淡入效果
		imageSwt.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in));
		//淡出效果
		imageSwt.setOutAnimation(AnimationUtils.loadAnimation(this,android.R.anim.fade_out));
		//设置图片转换效果
		imageSwt.setFactory(new ViewFactory() {

			@Override
			public View makeView() {
				ImageView imageView = new ImageView(MainActivity.this);
				imageView.setLayoutParams(new ImageSwitcher.LayoutParams(300, 300));
				imageView.setScaleType(ScaleType.FIT_CENTER);
				return imageView;
			}
		});
		//设置适配器
		SimpleAdapter simpleAdapter = new SimpleAdapter(this, list, R.layout.img, new String[]{"img"}, new int[]{R.id.img});
		//适配器
		gredView.setAdapter(simpleAdapter);
		//选中事件监听
		gredView.setOnItemSelectedListener(new OnItemSelectedListener() {

			@Override
			public void onItemSelected(AdapterView<?> parent, View view,
					int position, long id) {
				Log.i("onItemSelected", "onItemSelected");
				imageSwt.setImageResource(images[position]);
			}

			@Override
			public void onNothingSelected(AdapterView<?

> parent) {
				// TODO Auto-generated method stub

			}
		});
		//点击事件监听
		gredView.setOnItemClickListener(new OnItemClickListener() {

			@Override
			public void onItemClick(AdapterView<?> parent, View view,
					int position, long id) {
				Log.i("onItemClick", "onItemClick");
				imageSwt.setImageResource(images[position]);

			}
		});
	}

}

执行效果例如以下：