private void setCalendar(char y0, char y1, char y2, char y3, char M0, char M1, char d0, char d1) {
        calendar = Calendar.getInstance(timeZone, locale);
        int year = (y0 - '0') * 1000 + (y1 - '0') * 100 + (y2 - '0') * 10 + (y3 - '0');
        int month = (M0 - '0') * 10 + (M1 - '0') - 1;
        int day = (d0 - '0') * 10 + (d1 - '0');
//        calendar.set(year, month, day);
        calendar.set(Calendar.YEAR, year);
        calendar.set(Calendar.MONTH, month);
        calendar.set(Calendar.DAY_OF_MONTH, day);
    }
The value of a literal token, recorded as a string. For integers, leading 0x and 'l' suffixes are suppressed.
src/main/java/com/alibaba/fastjson/parser/JSONScanner.java