系统KeyboardView无法实现对个别按键进行自定义背景色，需要重写一个KeyboardView才可以

主要实现在于重写onDraw()方法，新建一个MyKeyboardView继承自KeyboardView

    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        Keyboard keyboard = getKeyboard();
        if (keyboard == null) return;
        List<Keyboard.Key> keys = keyboard.getKeys();
        if (keys != null && keys.size() > 0) {
            Paint paint = new Paint();
            paint.setTextAlign(Paint.Align.CENTER);
            Typeface font = Typeface.create(Typeface.SANS_SERIF, Typeface.BOLD);
            paint.setTypeface(font);
            paint.setAntiAlias(true);


            //此处进行特殊按键的背景色处理
            for (Keyboard.Key key : keys) {
                if (key.codes[0] == 34) {

                    //获取按键尺寸数据可优化
                    //绘制背景色
                    paint.setColor(getContext().getResources().getColor(R.color.gray_bfc3c7));
                    RectF rect=new RectF(key.x, key.y-Util.dip2px(BaseApplication.getAppContext(),2) + Util.dip2px(BaseApplication.getAppContext(),12),
                            key.x + key.width, key.y + key.height + Util.dip2px(BaseApplication.getAppContext(),10));
                    canvas.drawRoundRect(rect,Util.dip2px(BaseApplication.getAppContext(),4),Util.dip2px(BaseApplication.getAppContext(),4),paint);

                    //绘制icon
                    Drawable dr = getContext().getResources().getDrawable(R.drawable.key_board_cancel);
                    dr.setBounds(key.x+ Util.dip2px(BaseApplication.getAppContext(),8),
                            key.y + Util.dip2px(BaseApplication.getAppContext(),4+10),
                            key.x + key.width- Util.dip2px(BaseApplication.getAppContext(),8),
                            key.y + key.height - Util.dip2px(BaseApplication.getAppContext(),4-10));
                    dr.draw(canvas);


                }
            }
        }


    }

非常凌乱，仅供自己记录。