protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawColor(Color.WHITE);//设置画板的颜色为白色
Paint paint = new Paint(); //创建画笔
paint.setAntiAlias(true); //设置抗笔触
paint.setStrokeWidth(5);//设置线条宽度为3
paint.setStyle(Paint.Style.STROKE);//设置填充样式--描边|填充
paint.setColor(Color.BLUE);
//绘制蓝色的圆
canvas.drawCircle(50,50,30,paint);
paint.setColor(Color.YELLOW);
canvas.drawCircle(130,50,30,paint);
paint.setColor(Color.RED);
canvas.drawCircle(210,50,30,paint);
paint.setColor(Color.GREEN);
canvas.drawCircle(90,80,30,paint);
paint.setColor(Color.BLACK);
canvas.drawCircle(170,80,30,paint);
}