从一年中的某一天获取完整日期

var today = new Date();
var day = today.getDate();
var month = today.getMonth() + 1; // 月份从0开始，需要加1
var year = today.getFullYear();

var fullDate = year + '-' + month + '-' + day;
console.log(fullDate);

import java.time.LocalDate;

public class Main {
    public static void main(String[] args) {
        LocalDate today = LocalDate.now();
        int day = today.getDayOfMonth();
        int month = today.getMonthValue();
        int year = today.getYear();

        String fullDate = year + "-" + month + "-" + day;
        System.out.println(fullDate);
    }
}