xml-------布局-----------------------------------

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="match_parent"    android:layout_height="match_parent">

    <LinearLayout        android:orientation="horizontal"        android:layout_width="match_parent"        android:layout_height="wrap_content">        <Button            android:id="@+id/plus"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="增大透明度"            />        <Button            android:id="@+id/minus"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="降低透明度"            />        <Button            android:id="@+id/next"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="下一张"            />    </LinearLayout>

<ImageView    android:id="@+id/image1"    android:layout_width="wrap_content"    android:layout_height="280dp"    android:src="@drawable/img3"    android:scaleType="fitCenter"/><ImageView    android:id="@+id/image2"    android:layout_width="120dp"    android:layout_height="120dp"    android:background="#00f"    android:layout_margin="10dp"/></LinearLayout>

MainActivity.java-----------------Java调用----------------------------------

  int[] images=new int[]{          R.drawable.img1,          R.drawable.img2,          R.drawable.img3,          R.drawable.img4,          R.drawable.img5,

  };  int currentIMG=2;  private int alpha=255;  @Override  public void onCreate(Bundle savedInstanceState) {      super.onCreate(savedInstanceState);      setContentView(R.layout.imageviewer);      final Button plus=(Button) findViewById(R.id.plus);      final Button minus=(Button) findViewById(R.id.minus);      final ImageView image1=(ImageView) findViewById(R.id.image1);      final ImageView image2=(ImageView) findViewById(R.id.image2);      final Button next=(Button) findViewById(R.id.next);      next.setOnClickListener(new View.OnClickListener(){          @Override          public void onClick(View v) {              image1.setImageResource(images[++currentIMG%images.length]);          }      });     View.OnClickListener listener=new View.OnClickListener(){         @TargetApi(Build.VERSION_CODES.JELLY_BEAN)         @Override         public void onClick(View v){             if(v==plus){                 alpha+=20;             }             if(v==minus){                 alpha-=20;             }             if(alpha>=255){                 alpha=255;             }             if(alpha<=0){                 alpha=0;             }             image1.setImageAlpha(alpha);         }     };

      plus.setOnClickListener(listener);      minus.setOnClickListener(listener);image1.setOnTouchListener(new View.OnTouchListener() {    @TargetApi(Build.VERSION_CODES.JELLY_BEAN)    @Override    public boolean onTouch(View v, MotionEvent event) {        BitmapDrawable bitmapDrawable=(BitmapDrawable) image1.getDrawable();        Bitmap bitmap=bitmapDrawable.getBitmap();        double scale=1.0*bitmap.getHeight()/image1.getHeight();        int x=(int)  (event.getX()*scale);        int y=(int) (event.getY()*scale);        if(x+120>bitmap.getWidth()){            x=bitmap.getWidth()-120;        }        if(y+120>bitmap.getHeight()){            y=bitmap.getHeight()-120;        }        image2.setImageBitmap(Bitmap.createBitmap(bitmap,x,y,120,120));        image2.setImageAlpha(alpha);        return false;    }});  }