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>