在日常的开发中经常会遇到时间的处理。比如格式化后打印出来，得到明天的日期等等。java中也提供了很多类来处理时间，比如Calendar，java.util.Date，java.sql.Timestamp，SimpleDateFormat等等。昨天晚上写了一个工具类，封装了一些常用的方法。比如拿到当前的年月日时分秒，昨天，明天，之前n天，之后n天，格式化，还有各种时间类型之间的互相转换等等。如果还有什么需要的话，请告诉我，我好完善它。谢谢。

在最后提供了完整代码的下载，方便大家查看和使用。

java日期时间处理工具类封装源码实例：

Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/–> 1 package com.haode.bugtrace.util;

import java.sql.Time;
import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

/**
* 日期时间处理工具类
* @author laichendong
* @since 2010年2月22日23:09:09
*
*/
public class DateTime {

private long lNow = System.currentTimeMillis();
private Calendar cNow = Calendar.getInstance();
private Date dNow = new Date(lNow);
private Timestamp tNow = new Timestamp(lNow);
private java.sql.Date today = new java.sql.Date(lNow);
private java.sql.Time now = new java.sql.Time(lNow);

/**
* 默认构造方法
*/
public DateTime() {

}

/*private DateTime(long lNow, Calendar cNow, Date dNow, Timestamp tNow,
java.sql.Date today, Time now) {
this.lNow = lNow;
this.cNow = cNow;
this.dNow = dNow;
this.tNow = tNow;
this.today = today;
this.now = now;
}*/

/**
* 得到年
* @param c
* @return
*/
public static int getYear(Calendar c){
if(c != null){
return c.get(Calendar.YEAR);
}else{
return Calendar.getInstance().get(Calendar.YEAR);
}
}

/**
* 得到月份
* 注意，这里的月份依然是从0开始的
* @param c
* @return
*/
public static int getMonth(Calendar c){
if(c != null){
return c.get(Calendar.MONTH);
}else{
return Calendar.getInstance().get(Calendar.MONTH);
}
}

/**
* 得到日期
* @param c
* @return
*/
public static int getDate(Calendar c){
if(c != null){
return c.get(Calendar.DATE);
}else{
return Calendar.getInstance().get(Calendar.DATE);
}
}

/**
* 得到星期
* @param c
* @return
*/
public static int getDay(Calendar c){
if(c != null){
return c.get(Calendar.DAY_OF_WEEK);
}else{
return Calendar.getInstance().get(Calendar.DAY_OF_WEEK);
}
}

/**
* 得到小时
* @param c
* @return
*/
public static int getHour(Calendar c){
if(c != null){
return c.get(Calendar.HOUR);
}else{
return Calendar.getInstance().get(Calendar.HOUR);
}
}

/**
* 得到分钟
* @param c
* @return
*/
public static int getMinute(Calendar c){
if(c != null){
return c.get(Calendar.MINUTE);
}else{
return Calendar.getInstance().get(Calendar.MINUTE);
}
}

/**
* 得到秒
* @param c
* @return
*/
public static int getSecond(Calendar c){
if(c != null){
return c.get(Calendar.SECOND);
}else{
return Calendar.getInstance().get(Calendar.SECOND);
}
}

/**
* 得到指定或者当前时间前n天的Calendar
* @param c
* @param n
* @return
*/
public static Calendar beforeNDays(Calendar c, int n){
//偏移量，给定n天的毫秒数
long offset = n*24*60*60*1000;
Calendar calendar = null;
if(c != null){
calendar = c;
}else{
calendar = Calendar.getInstance();
}

calendar.setTimeInMillis(calendar.getTimeInMillis() – offset);
return calendar;
}

/**
* 得到指定或者当前时间后n天的Calendar
* @param c
* @param n
* @return
*/
public static Calendar afterNDays(Calendar c, int n){
//偏移量，给定n天的毫秒数
long offset = n*24*60*60*1000;
Calendar calendar = null;
if(c != null){
calendar = c;
}else{
calendar = Calendar.getInstance();
}

calendar.setTimeInMillis(calendar.getTimeInMillis() + offset);
return calendar;
}

/**
* 昨天
* @param c
* @return
*/
public static Calendar yesterday(Calendar c){
long offset = 1*24*60*60*1000;
Calendar calendar = null;
if(c != null){
calendar = c;
}else{
calendar = Calendar.getInstance();
}

calendar.setTimeInMillis(calendar.getTimeInMillis() – offset);
return calendar;
}

/**
* 明天
* @param c
* @return
*/
public static Calendar tomorrow(Calendar c){
long offset = 1*24*60*60*1000;
Calendar calendar = null;
if(c != null){
calendar = c;
}else{
calendar = Calendar.getInstance();
}

calendar.setTimeInMillis(calendar.getTimeInMillis() + offset);
return calendar;
}

/**
* 得到指定或者当前时间前offset毫秒的Calendar
* @param c
* @param offset
* @return
*/
public static Calendar before(Calendar c, long offset){
Calendar calendar = null;
if(c != null){
calendar = c;
}else{
calendar = Calendar.getInstance();
}

calendar.setTimeInMillis(calendar.getTimeInMillis() – offset);
return calendar;
}

/**
* 得到指定或者当前时间前offset毫秒的Calendar
* @param c
* @param offset
* @return
*/
public static Calendar after(Calendar c, long offset){
Calendar calendar = null;
if(c != null){
calendar = c;
}else{
calendar = Calendar.getInstance();
}

calendar.setTimeInMillis(calendar.getTimeInMillis() – offset);
return calendar;
}

/**
* 日期格式化
* @param c
* @param pattern
* @return
*/
public static String format(Calendar c, String pattern){
Calendar calendar = null;
if(c != null){
calendar = c;
}else{
calendar = Calendar.getInstance();
}
if(pattern == null || pattern.equals(“”)){
pattern = “yyyy年MM月dd日 HH:mm:ss”;
}
SimpleDateFormat sdf = new SimpleDateFormat(pattern);

return sdf.format(calendar.getTime());
}

/**
* Date类型转换到Calendar类型
* @param d
* @return
*/
public static Calendar Date2Calendar(Date d){
Calendar c = Calendar.getInstance();
c.setTime(d);
return c;
}

/**
* Calendar类型转换到Date类型
* @param c
* @return
*/
public static Date Calendar2Date(Calendar c){
return c.getTime();
}

/**
* Date类型转换到Timestamp类型
* @param d
* @return
*/
public static Timestamp Date2Timestamp(Date d){
return new Timestamp(d.getTime());
}

/**
* Calendar类型转换到Timestamp类型
* @param c
* @return
*/
public static Timestamp Calendar2Timestamp(Calendar c){
return new Timestamp(c.getTimeInMillis());
}

/**
* Timestamp类型转换到Calendar类型
* @param ts
* @return
*/
public static Calendar Timestamp2Calendar(Timestamp ts){
Calendar c = Calendar.getInstance();
c.setTime(ts);
return c;
}

/**
* 得到当前时间的字符串表示
* 格式2010-02-02 12:12:12
* @return
*/
public static String getTimeString(){
return format(Calendar.getInstance(), “yyyy-MM-dd HH:mm:ss”);
}

/**
* 标准日期格式字符串解析成Calendar对象
* @param s
* @return
*/
public static Calendar pars2Calender(String s){
Timestamp ts = Timestamp.valueOf(s);
return Timestamp2Calendar(ts);
}

//================以下是get和set方法=========================//

public long getLNow() {
return lNow;
}

public void setLNow(long now) {
lNow = now;
}

public Calendar getCNow() {
return cNow;
}

public void setCNow(Calendar now) {
cNow = now;
}

public Date getDNow() {
return dNow;
}

public void setDNow(Date now) {
dNow = now;
}

public Timestamp getTNow() {
return tNow;
}

public void setTNow(Timestamp now) {
tNow = now;
}

public java.sql.Date getToday() {
return today;
}

public void setToday(java.sql.Date today) {
this.today = today;
}

public java.sql.Time getNow() {
return now;
}

public void setNow(java.sql.Time now) {
this.now = now;
}

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub

}

}

http://www.cnblogs.com/coffee/archive/2010/02/23/1671834.html