要画这种圆形带阴影的头像，个人分解成三个图层

1,先画头像边缘的渐变

RadialGradient gradient = new RadialGradient(j/2,k/2,j/2,new int[]{0xff5d5d5d,0xff5d5d5d,0x00ffffff},new float[]{0.f,0.8f,1.0f}, Shader.TileMode.CLAMP);paint.setShader(gradient);canvas.drawCircle(j/2,k/2,j/2,paint);

2,截去出圆形头像Bitmap

/** * 转换图片成圆形 * @param bitmap 传入Bitmap对象 * @return */ public Bitmap toRoundBitmap(Bitmap bitmap) { int width = bitmap.getWidth(); int height = bitmap.getHeight(); float roundPx; float left,top,right,bottom,dst_left,dst_top,dst_right,dst_bottom; if (width <= height) { roundPx = width / 2 -5; top = 0; bottom = width; left = 0; right = width; height = width; dst_left = 0; dst_top = 0; dst_right = width; dst_bottom = width; } else { roundPx = height / 2 -5; float clip = (width - height) / 2; left = clip; right = width - clip; top = 0; bottom = height; width = height; dst_left = 0; dst_top = 0; dst_right = height; dst_bottom = height; } Bitmap output = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888); Canvas canvas = new Canvas(output); final int color = 0xff424242; final Paint paint = new Paint(); final Rect src = new Rect((int)left, (int)top, (int)right, (int)bottom); final Rect dst = new Rect((int)dst_left, (int)dst_top, (int)dst_right, (int)dst_bottom); final RectF rectF = new RectF(dst_left+15, dst_top+15, dst_right-20, dst_bottom-20); paint.setAntiAlias(true); canvas.drawARGB(0, 0, 0, 0); paint.setColor(color); canvas.drawRoundRect(rectF, roundPx, roundPx, paint); paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN)); canvas.drawBitmap(bitmap, src, dst, paint); return output; }

3,最后画上白边

Paint paint = new Paint(); paint.setColor(0xffffffff); paint.setStrokeWidth(10); paint.setStyle(Paint.Style.STROKE); canvas.drawCircle(j/2,k/2,j/2-20,paint);

PS：Android App常用图标尺寸规范
1. 程序启动图标：
LDPI (Low Density Screen，120 DPI)，其图标大小为 36 x 36 px。
MDPI (Medium Density Screen, 160 DPI)，其图标大小为 48 x 48 px。
HDPI (High Density Screen, 240 DPI)，其图标大小为 72 x 72 px。
xhdpi (Extra-high density screen, 320 DPI)，其图标大小为 96 x 96 px。
xxhdpi（xx-high density screen, 480 DPI）,其图标大小为144 x 144 px。

2.底部菜单图标
（1）大屏:
完整图片（红色）: 72 x 72 px
图标（蓝色）: 48 x 48 px
图标外边框（粉色）: 44 x 44 px

（2）中屏:
完整图片: 48 x 48 px
图标: 32 x 32 px
图标外边框: 30 x 30 px

（3）小屏:
完整图片: 36 x 36 px
图标: 24 x 24 px
图标外边框: 22 x 22 px

3. 弹出对话框顶部图标

小屏 24 x 24 px Low density screen (ldpi)
中屏 32 x 32 px Medium density screen (mdpi)
大屏 48 x 48 px High density screen (hdpi)

4. 长列表内部列表项图标

小屏 24 x 24 px Low density screen (ldpi)
中屏 32 x 32 px Medium density screen (mdpi)
大屏 48 x 48 px High density screen (hdpi)

5. 底部或顶部tab标签图标

（1）大屏 (hdpi) screens:
完整图片（红色）: 48 x 48 px
图标（蓝色）: 42 x 42 px

（2）中屏 (mdpi) screens:
完整图片: 32 x 32 px
图标: 28 x 28 px

（3）小屏(ldpi) screens:
完整图片: 24 x 24 px
图标: 22 x 22 px

6. 底部状态栏图标

ldpi (120 dpi) 18 x 18 px 小屏
mdpi (160 dpi) 24 x 24 px 中屏
hdpi (240 dpi) 36 x 36 px 大屏
xhdpi (320 dpi) 48 x 48 px 特大屏