直接看代码，解释。主要是用到图片处理的

PorterDuff.Mode.SRC_ATOPSRC_ATOP 

 源像素和目标像素相混合让上层图居中显示，达到加框效果

import android.app.Activity;  
import android.graphics.Bitmap;  
import android.graphics.BitmapFactory;  
import android.graphics.Canvas;  
import android.graphics.Paint;  
import android.graphics.PorterDuff;  
import android.graphics.PorterDuffXfermode;  
import android.graphics.Rect;  
import android.os.Bundle;  
import android.widget.ImageView;  
  
public class MainActivity extends Activity {  
    private ImageView imageView;  
  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
        imageView = (ImageView) findViewById(R.id.imageView1);  
  
        // 获得imageview中设置的图片  
        Bitmap lay1 = BitmapFactory.decodeResource(getResources(),  
                R.drawable.icon_folder);  
        Bitmap lay2 = BitmapFactory.decodeResource(getResources(),  
                R.drawable.mobileqq);  
        // 获得图片的宽，并创建结果bitmap  
        int width = lay1.getWidth();  
  
        Bitmap resultBmp = Bitmap.createBitmap(width, width,  
                Bitmap.Config.ARGB_8888);  
  
        Paint paint = new Paint();  
        Canvas canvas = new Canvas(resultBmp);  
  
        canvas.drawBitmap(lay1, 0, 0, paint);// 画下层  
  
        // 让上层的图标居中显示  
        int top = 0;  
        if (lay1.getHeight() > lay2.getHeight()) {  
            top = (lay1.getHeight() - lay2.getHeight()) / 2;  
        }else{  
            //这里可以判断图片是否大于框，进而再继续获取大于的多少，进行上层图片的缩放，然后再进行交集，方法就不写了  
        }  
        int left = 0;  
        if (lay1.getWidth() > lay2.getWidth()) {  
            left = (lay1.getWidth() - lay2.getWidth()) / 2;  
        }else{  
            //这里可以判断图片是否大于框，进而再继续获取大于的多少，进行上层图片的缩放，然后再进行交集，方法就不写了  
        }  
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_ATOP));// 选择交集去上层图片  
        canvas.drawBitmap(lay2, left, top, paint);  
        imageView.setImageBitmap(resultBmp);  
  
    }  
  
}