Android中通过反射实现圆角ImageView代码实例

private void init(){    paint = new Paint(Paint.ANTI_ALIAS_FLAG);        roundRect = new RectF(0, 0, getWidth() , getHeight());    radius = 40;    mPorterDuffXfermode = new PorterDuffXfermode(PorterDuff.Mode.SRC_IN) ;  }

 protected void onDraw(Canvas canvas) {        int sc = canvas.saveLayer(0, 0, getWidth() , getHeight(), null,        Canvas.MATRIX_SAVE_FLAG |        Canvas.CLIP_SAVE_FLAG |        Canvas.HAS_ALPHA_LAYER_SAVE_FLAG |        Canvas.FULL_COLOR_LAYER_SAVE_FLAG |        Canvas.CLIP_TO_LAYER_SAVE_FLAG);        roundRect.set(0, 0, getWidth(), getHeight());    canvas.drawRoundRect(roundRect, radius, radius, paint);        reflectSetXfermod();        super.onDraw(canvas);        canvas.restoreToCount(sc);  }

private void reflectSetXfermod(){    Drawable drawable = getDrawable();    if(drawable == null){      return;    }            Class bsClass = null;    Class[] innerClasses = BitmapDrawable.class.getDeclaredClasses();    for(Class innerClass :innerClasses)    {      String name = innerClass.getName();      System.out.println("-----innerClass---"+name);      if(name.equals("android.graphics.drawable.BitmapDrawable$BitmapState"))      {        bsClass = innerClass;      }          }        if(bsClass!= null){            try {        Field mPaintField = bsClass.getDeclaredField("mPaint");        mPaintField.setAccessible(true);        ConstantState constantState = ((BitmapDrawable)drawable).getConstantState();        Paint paint = (Paint)mPaintField.get(constantState);        paint.setXfermode(mPorterDuffXfermode);      } catch (IllegalArgumentException e) {        // TODO Auto-generated catch block        e.printStackTrace();      } catch (IllegalAccessException e) {        // TODO Auto-generated catch block        e.printStackTrace();      } catch (NoSuchFieldException e) {        // TODO Auto-generated catch block        e.printStackTrace();      }    }  }