java 给年份 一年多的第几天 积日 序日 求年月日

public static String getDateByday(int year, int days) {
int[] day_s ={0,31,28,31,30,31,30,31,31,30,31,30,31};
int day,month,i;
String m = “”,d=“”;
if(year%40 && year%100!=0 ||year%4000) {
day_s[2]=29;
}
day=1;
month=1;
for(i=1;i<13;i++) {
if(days<=day_s[i]) {
day=days;
break;
}
days-=day_s[i];
month++;
}
if(month<10){
m = “0”+month;
}else {
m = String.valueOf(month);
}
if(day<10){
d = “0”+day;
}else {
d = String.valueOf(day);
}
return year+“,”+m+“,”+ d;
}