做题日期问题

public static int dayOfYear(String date) {
        int day_count = 0;
        StringBuffer str = new StringBuffer();
        for(int i = 0;i < 4;i++){
            char ch = date.charAt(i);
            str.append(ch);
        }
        int year = Integer.parseInt(String.valueOf(str));
        int[] days = new int[]{0,31,28,31,30,31,30,31,31,30,31,30,31};
        //判断是否为闰年
        //boolean isleap = false;
        if(year %4 ==0 &&year%100!=0 ||year %400==0){
            //isleap = true;
            days[2] = 29;
        }
        StringBuffer str2 = new StringBuffer();
        for(int i = 5;i<7;i++){
            char ch = date.charAt(i);
            str2.append(ch);
        }
        int month = Integer.parseInt(String.valueOf(str2));
        if(month == 1 ){
        for(int i = 2;i <= month;i++){
            day_count += days[i];
        }
        } else {
            for(int i = 1;i < month;i++){
                day_count += days[i];
            }
        }
        StringBuffer str3 = new StringBuffer();
        for(int i = 8;i<10;i++){
            char ch = date.charAt(i);
            str3.append(ch);
        }
        int day = Integer.parseInt(String.valueOf(str3));
        day_count += day;
        return day_count;
    }