Java 关于时间获取与出生日期精确计算年龄算法

Java根据出生日期精确计算年龄算法

public static int getAge(Date dateOfBirth) {
        int age = 0;
        Calendar born = Calendar.getInstance();
        Calendar now = Calendar.getInstance();
        if (dateOfBirth != null) {
            now.setTime(new Date());
            born.setTime(dateOfBirth);
            if (born.after(now)) {
                throw new IllegalArgumentException("年龄不能超过当前日期");
            }
            age = now.get(Calendar.YEAR) - born.get(Calendar.YEAR);
            int nowDayOfYear = now.get(Calendar.DAY_OF_YEAR);
            int bornDayOfYear = born.get(Calendar.DAY_OF_YEAR);
            System.out.println("nowDayOfYear:" + nowDayOfYear + " bornDayOfYear:" + bornDayOfYear);
            if (nowDayOfYear < bornDayOfYear) {
                age -= 1;
            }
        }
        return age;
    }

    public static void main(String[] args) throws Exception {
        SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd");
        java.util.Date mydate = myFormatter.parse("2013-09-29");
        System.out.println(getAge(mydate));
    }

 

Java Calendar获取年、月、日、时间

Calendar c = Calendar.getInstance(TimeZone.getTimeZone(“GMT+08:00”));//获取东八区时间
  int year = c.get(Calendar.YEAR);//获取年
  int month = c.get(Calendar.MONTH) + 1;   //获取月份，0表示1月份
  int day = c.get(Calendar.DAY_OF_MONTH);//获取当前天数
  int first = c.getActualMinimum(c.DAY_OF_MONTH);//获取本月最小天数
  int last = c.getActualMaximum(c.DAY_OF_MONTH);//获取本月最大天数
  int time = c.get(Calendar.HOUR_OF_DAY);   //获取当前小时
  int min = c.get(Calendar.MINUTE);  //获取当前分钟
  int xx = c.get(Calendar.SECOND);  //获取当前秒

  SimpleDateFormat s=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
  String curDate = s.format(c.getTime());  //当前日期
  System.out.println("当前时间："+year + "-" + month + "-"+ day + " "+time + ":" + min +":" + xx);
  System.out.println("第一天和最后天：" + first +"," + last);
  System.out.println("当前日期curDate====：" + curDate);

输出结果：

> 当前时间：2012-9-25 22:50:54
> 第一天和最后天：1,30
> 当前日期curDate：2012-09-25 22:50:54

Calendar的计算：

  c.add(Calendar.YEAR, 1);
  c.add(Calendar.MONTH, 1);
  c.add(Calendar.DAY_OF_MONTH, 1);
  int year2 = c.get(Calendar.YEAR);
  int month2 = c.get(Calendar.MONTH) + 1;
  int day2 = c.get(Calendar.DAY_OF_MONTH);
  int firstD = c.getActualMinimum(c.DAY_OF_MONTH);
  int lastD = c.getActualMaximum(c.DAY_OF_MONTH);
  System.out.println("当前时间："+year2 + "-" + month2 + "-"+ day2 + " "+time + ":" + min +":" + xx);
  System.out.println("第一天和最后天：" + firstD +"," + lastD);

输出结果：

> 当前时间：2013-10-26 23:4:3
> 第一天和最后天：1,31

获取上个月的年、月、日：

Calendar c=Calendar.getInstance();
c.add(Calendar.MONTH, -1);//上个月
SimpleDateFormat s=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String year=String.valueOf(c.get(Calendar.YEAR));
String topDay = String.valueOf(c.getActualMinimum(Calendar.DAY_OF_MONTH)); 
String lastDay = String.valueOf(c.getActualMaximum(Calendar.DAY_OF_MONTH)); 
//上个月
String lastMonth=String.valueOf(c.get(Calendar.MONTH)+1).length()==2?String.valueOf(c.get(Calendar.MONTH)+1):"0"+String.valueOf(c.get(Calendar.MONTH)+1);
String topDayMonth=year+"-"+lastMonth+"-"+"01" + " 00:00:00"; 
String lastDayMonth = year+"-"+lastMonth+"-"+lastDay+ " 23:59:59";
System.out.println("###year:" + year);
System.out.println("###last month:" + lastMonth);
System.out.println("###topday:" + topDayMonth);
System.out.println("###lastday:" + lastDayMonth);

输出结果：

> year:2013
> last month:04
> topday:2013-04-01 00:00:00
> lastday:2013-04-30 23:59:59