將此函式在onDraw函式裡呼叫即可，畫筆paint自己初始化一個，根據需求請自行修改

private void drawText(Canvas canvas) {
        int measuredHeight = getMeasuredHeight();
        int measuredWidth = getMeasuredWidth();
        int paddingLeft = getPaddingLeft();
        int i = (measuredWidth - paddingLeft * 2) * getProgress() / getMax();
        String text = getProgress() + "%";
        bounds.setEmpty();
        paint.getTextBounds(text, 0, text.length(), bounds);
        canvas.drawText(text, i + paddingLeft - bounds.width() / 2, measuredHeight / 2.0f + bounds.height() / 2, paint);
    }