JAVA日期函数操作
经常用到时间日期类，所以就将常用的日期方法和属性都归纳总结如下，方便大家查找 1.计算某一月份的最大天数
Calendar time=Calendar.getInstance(); time.clear();
time.set(Calendar.YEAR,year);
time.set(Calendar.MONTH,i-1);//注意,Calendar对象默认一月为0 int day=time.getActualMaximum(Calendar.DAY_OF_MONTH);//本月份的天数 注:在使用set方法之前，最好先clear一下，否则很多信息会继承自系统当前时间 2.Calendar和Date的转化
(1) Calendar转化为Date
Calendar cal=Calendar.getInstance(); Date date=cal.getTime();
(2) Date转化为Calendar
Date date=new Date();
Calendar cal=Calendar.getInstance(); cal.setTime(date);
3.
格式
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化输出日期时间
Date date=new Date();
SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
System.out.println(df.format(date)); 4.计算一年中的第几星期
(1)计算某一天是一年中的第几星期
Calendar cal=Calendar.getInstance(); cal.set(Calendar.YEAR, 2006);
cal.set(Calendar.MONTH, 9);
cal.set(Calendar.DAY_OF_MONTH, 3); int weekno=cal.get(Calendar.WEEK_OF_YEAR); (2)计算一年中的第几星期是几号
SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");
Calendar cal=Calendar.getInstance(); cal.set(Calendar.YEAR, 2006);
cal.set(Calendar.WEEK_OF_YEAR, 1); cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
System.out.println(df.format(cal.getTime()));
输出:
2006-01-02
5.add()和roll()的用法
(1)add()方法
SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");
Calendar cal=Calendar.getInstance(); cal.set(Calendar.YEAR, 2006);
cal.set(Calendar.MONTH, 9);
cal.set(Calendar.DAY_OF_MONTH, 3); cal.add(Calendar.DATE, -4);
Date date=cal.getTime();
System.out.println(df.format(date)); cal.add(Calendar.DATE, 4);
date=cal.getTime();
System.out.println(df.format(date)); 输出:
2006-08-30
2006-10-03
(2)roll方法
cal.set(Calendar.YEAR, 2006); cal.set(Calendar.MONTH, 9); cal.set(Calendar.DAY_OF_MONTH, 3); cal.roll(Calendar.DATE, -4); date=cal.getTime();
System.out.println(df.format(date)); cal.roll(Calendar.DATE, 4); date=cal.getTime();
System.out.println(df.format(date)); 输出:
2006-10-29
2006-10-03
可见，roll()方法在本月内循环，一般使用add()方法;
6.计算两个任意时间中间的间隔天数
(1)传进Calendar对象
/** *//**计算两个时间之间相隔天数
* @param startday 开始时间
* @param endday 结束时间
* @return
*/
public int getIntervalDays(Calendar startday,Calendar endday)...{
//确保startday在endday之前
if(startday.after(endday))...{ Calendar cal=startday;
startday=endday;
endday=cal;
}
//分别得到两个时间的毫秒数
long sl=startday.getTimeInMillis(); long el=endday.getTimeInMillis();
long ei=el-sl;
//根据毫秒数计算间隔天数
return (int)(ei/(1000*60*60*24)); }
(2)传进Date对象
* @param startday 开始时间
* @param endday 结束时间
* @return
*/
public int getIntervalDays(Date startday,Date endday)...{
//确保startday在endday之前
if(startday.after(endday))...{ Date cal=startday;
startday=endday;
endday=cal;
}
//分别得到两个时间的毫秒数
long sl=startday.getTime();
long el=endday.getTime();
long ei=el-sl;
//根据毫秒数计算间隔天数
return (int)(ei/(1000*60*60*24)); }同理，可以用相同的方法计算出任意两个时间相隔的小时数，分钟数，秒钟数等 注:以上方法是完全按时间计算，有时并不能令人满意，如:
startday="2006-10-11 20:00:00" endday="2006-10-12 8:00:00"
计算结果为0，但是我们也许相让计算结果变为1，此时可以用如下方法实现: 在传参之前，先设定endday的时间，如:
endday.set(Calendar.HOUR_OF_DAY, 23); endday.set(Calendar.MINUTE, 59); endday.set(Calendar.SECOND, 59); endday.set(Calendar.MILLISECOND, 59); 这样再传进去startday,endday，则结果就如我们所愿了。不过，如果嫌以上方法麻烦，可以参考以下方法:
(3)改进精确计算相隔天数的方法
public int getDaysBetween (Calendar d1, Calendar d2) ...{
if (d1.after(d2)) ...{ // swap dates so that d1 is start and d2 is end
java.util.Calendar swap = d1;
d1 = d2;
d2 = swap;
}
int days = d2.get(Calendar.DAY_OF_YEAR) - d1.get(Calendar.DAY_OF_YEAR);
int y2 = d2.get(Calendar.YEAR); if (d1.get(Calendar.YEAR) != y2) ...{ d1 = (Calendar) d1.clone();
do ...{
days += d1.getActualMaximum(Calendar.DAY_OF_YEAR);//得到当年的实际天数
d1.add(Calendar.YEAR, 1);
} while (d1.get(Calendar.YEAR) != y2);
}
return days;
}
获取系统当前时间:
public static String getSystemTime(){
Date date=new Date();
SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); return df.format(date);
}
//字符串转化成时间类型(字符串可以是任意类型，只要和SimpleDateFormat中的格式一致
即可)
java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat("M/dd/yyyy hh:mm:ss a",java.util.Locale.US);
java.util.Date d = sdf.parse("5/13/2003 10:31:37 AM");
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String mDateTime1=formatter.format(d);
//当前时间
Calendar cal = Calendar.getInstance();
// SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss G E D F w W
a E F");
String mDateTime=formatter.format(cal.getTime());
//1年前日期
java.util.Date myDate=new java.util.Date();
long myTime=(myDate.getTime()/1000)-60*60*24*365;
myDate.setTime(myTime*1000);
String mDate=formatter.format(myDate);
//明天日期
myDate=new java.util.D
myTime=(myDate.getTime()/1000)+60*60*24;
myDate.setTime(myTime*1000);
mDate=formatter.format(myDate);
//两个时间之间的天数
SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd");
java.util.Date date= myFormatter.parse("2003-05-1");
java.util.Date mydate= myFormatter.parse("1899-12-30");
long day=(date.getTime()-mydate.getTime())/(24*60*60*1000);
//加半小时
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
java.util.Date date1 = format.parse("2002-02-28 23:16:00");
long Time=(date1.getTime()/1000)+60*30;
date1.setTime(Time*1000);
String mydate1=formatter.format(date1);
//年月周求日期
SimpleDateFormat formatter2 = new SimpleDateFormat("yyyy-MM F E");
java.util.Date date2= formatter2.parse("2003-05 5 星期五");
SimpleDateFormat formatter3 = new SimpleDateFormat("yyyy-MM-dd");
String mydate2=formatter3.format(date2);
//求是星期几
mydate= myFormatter.parse("2001-1-1");
SimpleDateFormat formatter4 = new SimpleDateFormat("E");
String mydate3=formatter4.format(mydate);
在 开发web应用中，针对不同的数据库日期类型，我们需要在我们的程序中对日期类型做各种不同的转换。若对应数据库数据是oracle的Date类型，即只 需要年月日的，可以选择使用java.sql.Date类型，若对应的是MSsqlserver数据库的DateTime类型，即需要年月日时分秒的，选 择java.sql.Timestamp类型
你可以使用dateFormat定义时间日期的格式，转一个字符串即可
package personal.jessica;
import java.util.Date;
import java.util.Calendar;
import java.sql.Timestamp;
import java.text.DateFormat;
import java.text.SimpleDateFormat; import java.util.Locale;
class Datetest{
/**
*method 将字符串类型的日期转换为一个timestamp(时间戳记java.sql.Timestamp)
*@param dateString 需要转换为timestamp的字符串
*@return dataTime timestamp
*/
public final static java.sql.Timestamp string2Time(String dateString)
throws java.text.ParseException {
DateFormat dateFormat;
dateFormat = new SimpleDateFormat("yyyy-MM-dd kk:mm:ss.SSS", Locale.ENGLISH);//
设定格式
//dateFormat = new SimpleDateFormat("yyyy-MM-dd kk:mm:ss", Locale.ENGLISH);
dateFormat.setLenient(false);
java.util.Date timeDate = dateFormat.parse(dateString);//util类型
java.sql.Timestamp dateTime = new
java.sql.Timestamp(timeDate.getTime());//Timestamp类型,timeDate.getTime()返回一
个long型
return dateTime;
}
/**
*method 将字符串类型的日期转换为一个Date(java.sql.Date)
*@param dateString 需要转换为Date的字符串
*@return dataTime Date
*/
public final static java.sql.Date string2Date(String dateString) throws java.lang.Exception {
DateFormat dateFormat;
dateFormat = new SimpleDateFormat("yyyy-MM-dd", Locale.ENGLISH); dateFormat.setLjava.util.Date timeDate = dateFormat.parse(dateString);//util类型
java.sql.Date dateTime = new java.sql.Date(timeDate.getTime());//sql类型
return dateTime;
}
public static void main(String[] args){
Date da = new Date();
//注意:这个地方da.getTime()得到的是一个long型的值
System.out.println(da.getTime());
//由日期date转换为timestamp
//第一种方法:使用new Timestamp(long)
Timestamp t = new Timestamp(new Date().getTime()); System.out.println(t);
//第二种方法:使用Timestamp(int year,int month,int date,int hour,int minute,int
second,int nano)
Timestamp tt = new Timestamp(Calendar.getInstance().get(
Calendar.YEAR) - 1900, Calendar.getInstance().get( Calendar.MONTH), Calendar.getInstance().get( Calendar.DATE), Calendar.getInstance().get( Calendar.HOUR), Calendar.getInstance().get( Calendar.MINUTE), Calendar.getInstance().get( Calendar.SECOND), 0);
System.out.println(tt);
try {
String sToDate = "2005-8-18";//用于转换成java.sql.Date的字符串
String sToTimestamp = "2005-8-18 14:21:12.123";//用于转换成java.sql.Timestamp的字符串
Date date1 = string2Date(sToDate);
Timestamp date2 = string2Time(sToTimestamp); System.out.println("Date:"+date1.toString());//结果显示
System.out.println("Timestamp:"+date2.toString());//结果显示
}catch(Exception e) {
e.printStackTrace();
}
}
}
下面是例子:
Java代码
package test;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Hashtable;
import javax.swing.JOptionPane;
public class Test2{
public static boolean isdate(String s){
String a[]=s.split("-");
boolean flg=true;
if(!(Integer.parseInt(a[0])>=1950 && Integer.parseInt(a[0])<=2050)){
flg=false;
}
return flg;
}
public static boolean checkDate(String s){
boolean ret = true;
try{
DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
ret = df.format(df.parse(s)).equals(s);
}
catch(ParseException e){
ret = false;
}
return ret;
}
public Object dateinfo(String s){
String a[]=s.split("-",2);
Hashtable fest =new Hashtable();
fest.put("01-01","元旦节");
fest.put("02-14","情人节");
fest.put("03-12","植树节");
fest.put("03-15","消费者节");
fest.put("04-01","愚人节");
fest.put("04-05","清明节");
fest.put("05-01","劳动节");
fest.put("06-01","儿童节");
fest.put("07-01","建党节");
fest.put("08-01","建 fest.put("09-10","教师节");
fest.put("10-01","国庆节");
fest.put("12-25","圣诞节");
if(fest.containsKey(a[1])){
return fest.get(a[1]);
}
else{
return "无节日";
}
}
public String xingzuo(Date s){
Calendar cal = Calendar.getInstance();
cal.setTime(s);
String xingzuo="无";
int day=cal.get(Calendar.DAY_OF_YEAR);
if((cal.get(Calendar.YEAR)%4==0)&&(cal.get(Calendar.YEAR)%100!=0)||(cal.get(Cale
ndar.YEAR)%400==0)){
if((day>=1 &&day<=19)||(day>=357&&day<=366)){
xingzuo= "魔蝎座";
}
else if(day>=20 &&day<=49){
xingzuo= "水瓶座";
}
else if(day>=50 &&day<=80){
xingzuo= "双鱼座";
}
else if(day>=81 &&day<=110){
xingzuo= "白羊座";
}
else if(day>=111 &&day<=141){
xingzuo= "金牛座";
}
else if(day>=142 &&day<=173){
xingzuo= "双子座";
}
else if(day>=174 &&day<=203){
xingzuo= "巨蟹座";
}
else if(day>=204 &&day<=235){
xingzuo= "狮子座";
}
else if(day>=236 &&day<=266){
xingzuo= "处女座";
}
else if(day>=267 &&day<=296){
xingzuo= "天秤座";
}
else if(day>=297 &&day<=326){
xingzuo= "天蝎座";
}
else if(day>=327 &&day<=356){
xingzuo= "射手座";
}
}
else{
if((day>=1 &&day<=19)||(day>=357&&day<=366)){
xingzuo= "魔蝎座";
}
else if(day>=20 &&day<=48){
xingzuo= "水瓶座";
}
else if(day>=49 &&day<=79){
xingzuo= "双鱼座";
}
else if(day>=80 &&day<=109){
xingzuo= "白羊座";
}
else if(day>=110 &&day<=140){
xingzuo= "金牛座";
}
else if(day>=141 &&day<=172){
xingzuo= "双子座";
}
else if(day>=173 &&day<=202){
xingzuo= "巨蟹座";
}
else if(day>=203 &&day<=234){
xingzuo= "狮子座";
}
else if(day>=235 &&day<=265){
xingzuo= "处女座";
}
else if(day>=266 &&day<=295){
xingzuo= "天秤座";
else if(day>=296 &&day<=325){
xingzuo= "天蝎座";
}
else if(day>=326 &&day<=355){
xingzuo= "射手座";
}
}
return xingzuo;
}
public Date parseDate(String s){
SimpleDateFormat bartDateFormat = new SimpleDateFormat("yyyy-MM-dd");
try {
Date date3 = bartDateFormat.parse(s);
date3=bartDateFormat.parse(s);
return date3;
}
catch (Exception ex) {
return null;
}
}
public static void main(String[] args) {
Calendar cal = Calendar.getInstance();
Test2 test2=new Test2();
String date1=JOptionPane.showInputDialog("请你输入日期，格式如
2000-10-15");
while(!(Test2.checkDate(date1)&&Test2.isdate(date1))){
date1=JOptionPane.showInputDialog("请你输入日期，格式如2000-10-15");
}
SimpleDateFormat bartDateFormat1 = new
SimpleDateFormat("yyyy,MM,dd,EEEE");
SimpleDateFormat bartDateFormat2 = new SimpleDateFormat("yyyy-MM-dd");
Date date2=test2.parseDate(date1);
String festinfo=(String)test2.dateinfo(date1);
System.out.println(bartDateFormat1.format(date2) +","+ festinfo+","+
test2.xingzuo(date2));
String day=JOptionPane.showInputDialog("请你输入要查询N天后的日期信
息");
cal.setTime(date2);
cal.add(Calendar.DATE, Integer.parseInt(day));
String date5=bartDateFormat2.format(cal.getTime());
festinfo=(String)test2.dateinfo(date5);
System.out.println(bartDateFormat1.format(cal.getTime())+","+ festinfo+","+ test2.xingzuo(cal.getTime()));
}
}
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