java中的日期和时间处理示例

import?java.util.*;
import?java.text.SimpleDateFormat;
import?java.sql.Date;
import?java.sql.Time;
import?java.sql.Timestamp;

public?class?TestDateTime
{
????public?static?void?main(String[]?argv)
????{
????????long?nCurrentTime?=?System.currentTimeMillis();
????????java.util.Date?utilDate?=?new?java.util.Date(nCurrentTime);

????????//以下是用于数据库操作的日期和时间类
????????java.sql.Date?sqlDate?=?new?java.sql.Date(utilDate.getTime());??

????????//java.util.Date和java.sql.Date的转换
????????java.sql.Time?sqlTime?=?new?java.sql.Time(utilDate.getTime());
????????java.sql.Timestamp?sqlTimestamp?=?new?java.sql.Timestamp(nCurrentTime);

????????//Calendar用于获取指定的时间项（字段）
????????Calendar?calendar?=?Calendar.getInstance();
????????calendar.setTimeInMillis(nCurrentTime);

????????int?year?=?calendar.get(Calendar.YEAR);
????????int?month?=?calendar.get(Calendar.MONTH)?+?1;???//注意：返回的月份是基于0的！
????????int?day?=?calendar.get(Calendar.DAY_OF_MONTH);
????????int?hour?=?calendar.get(Calendar.HOUR_OF_DAY);
????????int?minute?=?calendar.get(Calendar.MINUTE);
????????int?second?=?calendar.get(Calendar.SECOND);

????????System.out.println("Current?date?is:?"?+?year?+?"年"?+?month?+?"月"?+?day?+?"日");
????????System.out.println("Current?time?is:?"?+?hour?+?"时"?+?minute?+?"分"?+?second?+?"秒");

????????//SimpleDateFormat用于格式化日期和时间
????????SimpleDateFormat?df?=?new?SimpleDateFormat("yyyy-MM-dd?HH:mm:ss");
????????String?szDatetime1?=?df.format(utilDate);
????????System.out.println("Current?datetime?is:?"?+?szDatetime1);

????????//以下计算两个日期值之间相差的时间
????????java.util.Date?date2?=?new?java.util.Date(nCurrentTime?-?24600?*?1000);

????????long?nMilliSeconds?=?utilDate.getTime()?-?date2.getTime();
????????long?nSeconds?=??nMilliSeconds?/?1000;??//把毫秒换算成秒
????????double?nDays?=?nSeconds?/?(24d?*?60d?*?60d);??//把秒换算成天

????????String?szDatetime2?=?df.format(date2);
????????System.out.println("Time?between?"?+?szDatetime1?+?"?and?"?+?szDatetime2?+?"?is?"?+?nSeconds?+?"?seconds?("?+?nDays?+?"?days)");
????}
}

程序运行结果：


C:\java>java???TestDateTime
Current?date?is:?2005年1月2日
Current?time?is:?15时55分45秒
Current?datetime?is:?2005-01-02?15:55:45
Time?between?2005-01-02?15:55:45?and?2005-01-02?09:05:45?is?24600?seconds?(0.2847222222222222?days)

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