Android应用中图片浏览时实现自动切换功能的方法详解

先给最终效果图：

当我们在最下边的gallery中切换图片时，上面的大图片会自动切换，切换时有动画效果哦，很简单的一个程序，有待完善更多的功能！

activity代码：

package cn.com.chenzheng_java; 
import android.app.Activity; 
import android.content.Context; 
import android.os.Bundle; 
import android.view.View; 
import android.view.ViewGroup; 
import android.view.Window; 
import android.view.animation.AnimationUtils; 
import android.widget.AdapterView; 
import android.widget.BaseAdapter; 
import android.widget.Gallery; 
import android.widget.ImageSwitcher; 
import android.widget.ImageView; 
import android.widget.Toast; 
import android.widget.AdapterView.OnItemSelectedListener; 
import android.widget.ImageView.ScaleType; 
import android.widget.ViewSwitcher.ViewFactory; 
public class GalleryActivity extends Activity implements OnItemSelectedListener { 
  int[] imagesId = new int[] { R.drawable.a1, R.drawable.a2, R.drawable.a3, 
      R.drawable.a4 
  }; 
  int index = R.drawable.a1; 
  ImageSwitcher imageSwitcher; 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
     
    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    setContentView(R.layout.gallery); 
    Gallery gallery = (Gallery) findViewById(R.id.gallery1); 
    gallery.setOnItemSelectedListener(this); 
    imageSwitcher = (ImageSwitcher) findViewById(R.id.imageSwitcher); 
    imageSwitcher.setVisibility(View.VISIBLE); 
     
    imageSwitcher.setInAnimation(AnimationUtils.loadAnimation( 
        getApplicationContext(), android.R.anim.fade_in)); 
    imageSwitcher.setOutAnimation(AnimationUtils.loadAnimation( 
        getApplicationContext(), android.R.anim.fade_out)); 
    imageSwitcher.setFactory(new ViewFactory() { 
       
      @Override 
      public View makeView() { 
        ImageView imageView = new ImageView(GalleryActivity.this); 
        // 设置截取模式 
        imageView.setScaleType(ScaleType.CENTER_INSIDE); 
        imageView.setBackgroundResource(R.drawable.ground); 
        Toast.makeText(getApplicationContext(), "执行了一次", 
            Toast.LENGTH_SHORT).show(); 
        return imageView; 
      } 
    }); 
    gallery.setVisibility(View.VISIBLE); 
    gallery.setAdapter(new ImageAdapter(this)); 
  } 
  class ImageAdapter extends BaseAdapter { 
    private Context context2; 
    public ImageAdapter(Context context) { 
      context2 = context; 
    } 
    @Override 
    public int getCount() { 
      return imagesId.length; 
    } 
    @Override 
    public Object getItem(int position) { 
      return imagesId[position]; 
    } 
    @Override 
    public long getItemId(int position) { 
      return position; 
    } 
    @Override 
    public View getView(int position, View image2, ViewGroup parent) { 
      ImageView image = new ImageView(context2); 
      image.setBackgroundResource(imagesId[position]); 
       
      image.setScaleType(ScaleType.CENTER_INSIDE); 
      return image; 
    } 
  } 
   
  @Override 
  public void onItemSelected(AdapterView<?> parent, View view, int position, 
      long id) { 
    imageSwitcher.setImageResource(imagesId[position]); 
  } 
  @Override 
  public void onNothingSelected(AdapterView<?> parent) { 
  } 
} 

gallery.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
 xmlns:android="http://schemas.android.com/apk/res/android" 
 android:layout_width="fill_parent" 
 android:layout_height="fill_parent" 
 android:orientation="vertical" 
 android:gravity="center_horizontal" 
 > 
 <ImageSwitcher 
  android:id="@+id/imageSwitcher" 
  android:layout_height="350dp" 
  android:layout_width="fill_parent"  
 ></ImageSwitcher> 
  <Gallery android:id="@+id/gallery1"  
  android:gravity="center" 
  android:layout_width="70dp"  
  android:layout_height="100dp"></Gallery> 
</LinearLayout> 

升级版

较之上面的，效果还是一样的，只不过这里添加了这么以下几个功能：

第一：下方图片的自适应长宽（在保证长宽比例的情况下哦）

第二：触摸大图同样可以进行图片切换（没有机器，没法测试，但是基本的思路还是正确的）

代码：

activity代码：

package cn.com.chenzheng_java; 
import java.text.DecimalFormat; 
import android.app.Activity; 
import android.content.Context; 
import android.content.res.Resources; 
import android.graphics.Bitmap; 
import android.graphics.BitmapFactory; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.MotionEvent; 
import android.view.View; 
import android.view.ViewGroup; 
import android.view.Window; 
import android.view.View.OnTouchListener; 
import android.view.animation.AnimationUtils; 
import android.widget.AdapterView; 
import android.widget.BaseAdapter; 
import android.widget.Gallery; 
import android.widget.ImageSwitcher; 
import android.widget.ImageView; 
import android.widget.Toast; 
import android.widget.AdapterView.OnItemSelectedListener; 
import android.widget.Gallery.LayoutParams; 
import android.widget.ImageView.ScaleType; 
import android.widget.ViewSwitcher.ViewFactory; 
public class GalleryActivity extends Activity implements OnItemSelectedListener ,OnTouchListener{ 
  int[] imagesId = new int[] { R.drawable.a1, R.drawable.a2, R.drawable.a3, 
      R.drawable.a4 
  }; 
  int index = 0; 
  ImageSwitcher imageSwitcher; 
  int maxImageWidth = 70; 
  int maxImageHeight = 100; 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
     
    requestWindowFeature(Window.FEATURE_NO_TITLE); 
    setContentView(R.layout.gallery); 
    Gallery gallery = (Gallery) findViewById(R.id.gallery1); 
    gallery.setOnItemSelectedListener(this); 
    imageSwitcher = (ImageSwitcher) findViewById(R.id.imageSwitcher); 
    imageSwitcher.setVisibility(View.VISIBLE); 
     
    imageSwitcher.setInAnimation(AnimationUtils.loadAnimation( 
        getApplicationContext(), android.R.anim.fade_in)); 
    imageSwitcher.setOutAnimation(AnimationUtils.loadAnimation( 
        getApplicationContext(), android.R.anim.fade_out)); 
    imageSwitcher.setFactory(new ViewFactory() { 
       
      @Override 
      public View makeView() { 
        ImageView imageView = new ImageView(GalleryActivity.this); 
        // 设置截取模式 
        imageView.setScaleType(ScaleType.CENTER_INSIDE); 
        imageView.setBackgroundResource(R.drawable.ground); 
        Toast.makeText(getApplicationContext(), "执行了一次", 
            Toast.LENGTH_SHORT).show(); 
        return imageView; 
      } 
    }); 
    gallery.setVisibility(View.VISIBLE); 
    gallery.setAdapter(new ImageAdapter(this)); 
  } 
  class ImageAdapter extends BaseAdapter { 
    private Context context2; 
    public ImageAdapter(Context context) { 
      context2 = context; 
    } 
    @Override 
    public int getCount() { 
      return imagesId.length; 
    } 
    @Override 
    public Object getItem(int position) { 
      return imagesId[position]; 
    } 
    @Override 
    public long getItemId(int position) { 
      return position; 
    } 
     
    @Override 
    public View getView(int position, View convertView, ViewGroup parent) { 
      index = position; 
      ImageView image = new ImageView(context2); 
      Resources resources = context2.getResources(); 
      // 加载图片为Bitmap位图 
      Bitmap bitmap = BitmapFactory.decodeResource(resources, imagesId[position]); 
      Log.i("是否可以decode这张图片", (bitmap!=null)+""); 
      // 图片的原始大小 
      int bitMapWidth = bitmap.getWidth(); 
      int bitMapHeight = bitmap.getHeight(); 
      Log.i("bitMapWidth", bitMapWidth+""); 
      Log.i("bitMapHeight", bitMapHeight+""); 
      // 缩小或者放大的倍数关系 
      double scale; 
      double widthScale = (maxImageWidth*100)/(bitMapWidth*100.0);//这里乘以100然后除以100.0的目的是为了让其返回double类型 
      double heightScale = (maxImageHeight*100)/(bitMapHeight*100.0); 
      // 规划获得的格式（小数点后两位） 
      DecimalFormat decimalFormat = new DecimalFormat("#.00"); 
      widthScale = Double.valueOf(decimalFormat.format(widthScale)); 
      heightScale = Double.valueOf(decimalFormat.format(heightScale)); 
      Log.i("widthScale", widthScale+""); 
      Log.i("heightScale", heightScale+""); 
      if(widthScale>= heightScale){ 
        scale = widthScale; 
      } 
      else{ 
        scale = heightScale; 
      } 
      Log.i("scale", scale+""); 
      // 根据原图片生成一个缩放后的图片 
      Bitmap bitmap2 = Bitmap.createScaledBitmap(bitmap, (int)(bitMapWidth*scale), (int)(bitMapHeight*scale), true); 
      // 将图片绑定到ImageView 
      image.setImageBitmap(bitmap2); 
       
      // image.setScaleType(ScaleType.CENTER_INSIDE); 
      image.setAdjustViewBounds(true);// 自适应边框处理 
      image.setLayoutParams(new Gallery.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); 
      return image; 
    } 
  } 
   
  @Override 
  public void onItemSelected(AdapterView<?> parent, View view, int position, 
      long id) { 
    imageSwitcher.setImageResource(imagesId[position]); 
  } 
  @Override 
  public void onNothingSelected(AdapterView<?> parent) { 
  } 
  int i = 0 ; 
   
  @Override 
  public boolean onTouch(View v, MotionEvent event) { 
    Log.i("是否正在触摸", "yes"); 
    int actionName = event.getAction(); 
    float []position = null; 
    //被按下时 
    if(actionName==MotionEvent.ACTION_DOWN){ 
      i = 0; 
    } 
    // 被按着拖动时 
    if(actionName == MotionEvent.ACTION_MOVE) 
    { 
      position[i] = event.getX(); 
      ++i; 
    } 
    if(actionName == MotionEvent.ACTION_UP) 
    { 
      if(position[position.length]>position[position.length-1]){ 
        if((index+1)>imagesId.length){ 
          imageSwitcher.setImageResource(imagesId[index]); 
        } 
        else{ 
          imageSwitcher.setImageResource(imagesId[index+1]); 
        } 
      } 
      else{ 
        if((index-1)<0){ 
          imageSwitcher.setImageResource(imagesId[0]); 
        } 
        else{ 
          imageSwitcher.setImageResource(imagesId[index-1]); 
        } 
      } 
    } 
    return true; 
  } 
} 

gallery.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
 xmlns:android="http://schemas.android.com/apk/res/android" 
 android:layout_width="fill_parent" 
 android:layout_height="fill_parent" 
 android:orientation="vertical" 
 android:gravity="center_horizontal" 
 > 
 <ImageSwitcher 
  android:id="@+id/imageSwitcher" 
  android:layout_height="350dp" 
  android:layout_width="fill_parent"  
 ></ImageSwitcher> 
  <Gallery android:id="@+id/gallery1"  
  android:gravity="center" 
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"></Gallery> 
</LinearLayout> 

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