初识ImageSwither

 imageswitcher继承自viewswitcher，使用ImageSwither只需要两步：

1.为ImageSwither提供一个ViewFactory，该ViewFactory生成的View必须是ImageView.

2.需要切换图片时，只要调用ImageSwither的setImageResource，setImageDrawable，setImageURI方法更换图片即可。

下面是一个gallery，上面是个imageSwither，在gallery里每选择一张图片就会显示到Swither上，并有渐入渐出动画效果。

ImageSwitcher + GridView

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.FrameLayout.LayoutParams;
import android.widget.GridView;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.ViewSwitcher.ViewFactory;

public class ImageSwitcherTest extends Activity {
    private GridView gridView;
    private ImageSwitcher switcher;

    private int[] mImage = new int[] { R.drawable.p0, R.drawable.p13,
            R.drawable.p16, R.drawable.p2, R.drawable.p4, R.drawable.p8 };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.layout_imageswitcher);
        switcher = (ImageSwitcher) findViewById(R.id.imageSwitcher2);

        switcher.setFactory(new ViewFactory() {

            @Override
            public View makeView() {
                // TODO Auto-generated method stub

                ImageView imageView = new ImageView(ImageSwitcherTest.this);
                imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
                /*imageView.setLayoutParams(new ImageSwitcher.LayoutParams(
                        LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));*/
                return imageView;
            }
        });
        
        ImageAdapter adapter = new ImageAdapter();
        gridView = (GridView) findViewById(R.id.gridView2);    
        gridView.setAdapter(adapter);
        
        gridView.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                // TODO Auto-generated method stub
                switcher.setImageResource(mImage[position]);
            }
        });
        
    }

    class ImageAdapter extends BaseAdapter {

        @Override
        public int getCount() {
            // TODO Auto-generated method stub
            return mImage.length;
        }

        @Override
        public Object getItem(int position) {
            // TODO Auto-generated method stub
            return mImage[position];
        }

        @Override
        public long getItemId(int position) {
            // TODO Auto-generated method stub
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            // TODO Auto-generated method stub
            ImageView imageView = new ImageView(ImageSwitcherTest.this);
            imageView.setImageResource(mImage[position]);
            return imageView;
        }

    }
}

<?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" >

    <GridView
        android:id="@+id/gridView2"
        android:layout_width="match_parent"
        android:layout_height="254dp"
        android:numColumns="3"
        android:horizontalSpacing="pt"
        android:verticalSpacing="2pt"
        android:gravity="center"
         >
    </GridView>

    <ImageSwitcher
        android:id="@+id/imageSwitcher2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0.94"
        android:layout_gravity="center_horizontal"
        android:inAnimation="@android:anim/fade_in"
        android:outAnimation="@android:anim/fade_out" 
        >
    </ImageSwitcher>

</LinearLayout>